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Fil: Seijo, Mariana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Inmunologia, Genetica y Metabolismo. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Inmunologia, Genetica y Metabolismo; Argentina

The characterization of autochthonous cultures based on their contribution to cheese flavor is an additional selection criterion for their use in cheese making. The objective of the present work was to assess the ability of three strains of mesophilic lactobacilli: Lactobacillus casei 72 (Lc72), L. paracasei 90 (Lp90), and L. plantarum 91 (Lp91), one strain of thermophilic lactobacillus: L. helveticus 209 (Lh209), and the thermophilic–mesophilic combinations, to grow and produce aroma compounds in a hard cheese model. Microbiological counts, pH, and the profiles of carbohydrates, organic acids, and volatile compounds were analyzed during incubation for 14 days at 37 ℃. The population of mesophilic lactobacilli reached levels around 8.0 log CFU ml−1 at three days, but then decreased until ∼7.0 log CFU ml−1 toward 14 days. Thermophilic lactobacillus population reached and maintained levels around 7.7 log CFU ml−1 during incubation. Carbohydrates were absent in the hard cheese model, and so no change in the pH values and in the levels of lactic acid was detected. Mesophilic lactobacilli, inoculated individually or in association with Lh209, metabolized the citric acid and produced ethanoic acid. The profiles of volatile compounds of mesophilic lactobacilli (characterized mainly by butan-2-one, 3-hydroxybutan-2-one, 3-methylbutan-1-ol, hexan-1-ol, 2-phenylethanol, and ethanoic acid) were different from the profile of thermophilic lactobacillus Lh209 (characterized mainly by heptan-2-one, ethyl acetate, isoamyl hexanoate, pentan-1-ol, decanoic acid, and 2- and 3-methylbutanal). Cooperative effects in the production of compounds related to cheese flavor, such as 3-hydroxybutan-2-one, ethyl butanoate, ethanol, pentan-2-ol, hexan-1-ol, benzeneacetaldehyde, 2-phenylethanol, and heptanoic acid, were largely evidenced between Lh209 and Lp91; in a lesser extent, cooperative effects were also found for Lh209+Lp90 for the following compounds: 3-hydroxybutan-2-one, isoamyl acetate, and ethanoic acid. Of the mesophilic lactobacilli strains evaluated, Lp91 and Lp90 would be interesting candidates for its use as adjunct cultures in hard cheeses to improve and diversify the flavor. Fil: Cuffia, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The aim of this work was to evaluate the impact of two factors on the ripening profiles of hard cooked cheeses: (F1) the growth medium for the primary and adjunct cultures, constituted by autochthonous strains: Lactobacillus helveticus 209 (Lh209) and Lactobacillus paracasei 90 (Lp90), respectively, and (F2) the addition of L. paracasei Lp90 as adjunct culture. Four types of cheeses were made: W and M cheeses in which only Lh209 was added after its growth in whey and MRS, respectively; Wa and Ma cheeses in which both strains (Lh209 and Lp90) were added after their growth in whey and MRS, respectively. Physicochemical and microbial composition, proteolysis and profiles of organic acids and volatile compounds were analyzed. According to the methodology of the cultures preparation, W and Wa cheeses showed a higher level of secondary proteolysis and lower level of primary proteolysis (P < 0·05), lower content of citric and acetic acids and higher amount of propionic acid (P < 0·05), in comparison with M and Ma cheeses. The incorporation of Lp90 increased the secondary proteolysis (P < 0·05), decreased the citric acid (P < 0·05), and increased the propionic acid only when was added after their growth in whey (P < 0·05). Both factors significantly modified the percentages of the volatile compounds grouped in chemical families; in addition, for the half of the compounds detected, significant differences were found. Based on the obtained results, the use of Lp90 as an adjunct in hard cooked cheeses, and the preincubation of the cultures in whey are strategies to accelerate the cheese ripening and to enhance the production of some characteristic compounds of this type of cheeses, such as propan-2-one, hexan-2-one, 2- A nd 3-methyl butanal, heptan-2-ol, acetic and 3-methylbutanoic acids and 3-hydroxy butan-2-one. Fil: Cuffia, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The waste and by-products of the soybean industry could be an economic source of nutrients to satisfy the high nutritional demands for the cultivation of lactic acid bacteria. The aims of this work were to maximize the biomass production of Lacticaseibacillus paracasei 90 (L90) in three culture media formulated from an effluent derived from soy protein concentrate production and to assess the effects these media have on the enzymatic activity of L90, together with their influence on its fermentation profile in milk. The presence of essential minerals and fermentable carbohydrates (sucrose, raffinose, and stachyose) in the effluent was verified. L90 reached high levels of microbiological counts (∼ 9 log cfu mL−1) and dry weight (> 1 g L−1) on the three optimized media. Enzymatic activities (lactate dehydrogenase and β-galactosidase) of L90, and its metabolism of lactose and citric acid, as well as lactic acid and pyruvic acid production in milk, were modified depending on the growth media. The ability of the L90 to produce the key flavour compounds (diacetyl and acetoin) was maintained or improved by growing in the optimized media in comparison with MRS. Fil: Beret, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Vera Candioti, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Sánchez, Renzo. Municipalidad de Gualeguaychu (entre Rios).; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Galactooligosaccharides (GOS) are non-digestible oligosaccharides with recognized prebiotic role. The present study aims to evaluate a β-galactosidase from K. lactis during soft cheese making and to analyse the impact on carbohydrates metabolism, proteolysis, and volatile compounds production, physicochemical and microbiological characteristics of the product. The enzyme was added to cheese milk (fluid milk plus whey powder) before (40 min.) or simultaneously of the starter addition (Ep and E treatments, respectively); cheese without enzyme addition was also made (C treatment). Also, we characterized fresh and soft commercial cheeses from the point of view of carbohydrate fraction, highlighting GOS, and organic acid profiles. The inclusion of the enzyme in soft cheese making produced a delay in reaching the target pH (~5.2). Carbohydrate fermentation profiles differed among treatments during cheese making and ripening. GOS were only detected in Ep and E cheeses (0.88 and 0.51 g/100 g, respectively). Lactose content was lower, and glucose and galactose levels were higher in E and Ep than C. No differences in physicochemical and microbial composition and organic acids profiles among samples were observed. Bioformation of volatile compounds belonging to the chemical families of aldehydes, ketones, alcohols, esters and acids, was not substantially affected by the modification in the carbohydrate profile. GOS were not detected in any of the commercial cheeses; great variations in the carbohydrate contents and organic acids were found. The results obtained demonstrate the feasibility of obtaining cheeses with GOS. Although the GOS values achieved are not adequate enough for the desired effect, the proposed technological approach turned out to be satisfying and original. Cheeses with prebiotic fiber are not still widespread in the market. Fil: Vénica, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Starter cultures of Lactobacillus helveticus used in hard cooked cheeses play an important role in flavor development. In this work, we studied the capacity of three strains of L. helveticus, two autochthonous (Lh138 and Lh209) and one commercial (LhB02), to grow and to produce volatile compounds in a hard cheese extract. Bacterial counts, pH, profiles of organic acids, carbohydrates, and volatile compounds were analyzed during incubation of extracts for 14 days at 37 ℃. Lactobacilli populations were maintained at 106 CFU ml−1 for Lh138, while decreases of approx. 2 log orders were found for LhB02 and Lh209. Both Lh209 and LhB02 slightly increased the acetic acid content whereas mild increase in lactic acid was produced by Lh138. The patterns of volatiles were dependent on the strain which reflect their distinct enzymatic machineries: LhB02 and Lh209 produced a greater diversity of compounds, while Lh138 was the least producer strain. Extracts inoculated with LhB02 and Lh 209 were characterized by ketones, esters, alcohols, aldehydes, and acids, whereas in the extracts with Lh138 the main compounds belonged to aromatic, aldehydes, and ketones groups. Therefore, Lh209 and LhB02 could represent the best cheese starters to improve and intensify the flavor, and even a starter composed by combinations of LhB02 or Lh209 with Lh138 could also be a strategy to diversify cheese flavor. Fil: Cuffia, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The influence of several disruption treatments on the viability and the release of intracellular enzymes of two strains of Streptococcus thermophilus (St1 and St2) was studied. In addition, the impact of the incorporation of disrupted cultures of St2 in Cremoso cheese was investigated. Enzymatic (mutanolysin) and mechanical treatments (bead mill and ultrasound) were the most effective for lysis, while chemical methods (ethanol and SDS) were effective as permeabilising agents. Physical methods (freeze and heat shock) were not suitable for disruption. The application of disrupted cultures of St2 in Cremoso cheese led to slight changes on the ripening profiles: decrease in lactose level, and increase in total free amino acids and acetic acid. This work demonstrated that certain types of disrupted St2 cultures could be suitable as source of key enzymes for the production of food with improved properties, such as lactose-hydrolysed dairy products or cheeses with higher proteolysis. Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

AIM:To determine the protective capacity against Salmonella infection in mice of the cell-free fraction (postbiotic) of fermented milk, produced at laboratory and industrial level.METHODS AND RESULTS:The proteolytic activity (PA) of five commercial cultures and eleven autochthonous Lactobacillus strains was evaluated. The DSM-100H culture displayed the highest PA and it was selected for further studies. The capacity of the postbiotics produced by pH-controlled fermentation to stimulate the production of secretory-IgA in faeces and to protect mice against Salmonella infection was evaluated. A significant increase of S-IgA in faeces of mice fed 14 days the postbiotic obtained at the laboratory (F36) was detected compared to control animals. A significantly higher survival was observed in mice fed the F36 and the FiSD (industrial product) compared to controls.CONCLUSION:The postbiotics obtained showed immunomodulatory and protective capacity against Salmonella infection in mice.SIGNIFICANCE AND IMPACT OF THE STUDY:The pH-controlled milk fermentation by the proteolytic DSM-100H culture could be a suitable strategy to obtain a food ingredient to be added to a given food matrix, not adequate to host viable cells of probiotics, to confer it enhanced functionality and thus expand the functional food market. This article is protected by copyright. All rights reserved. Fil: Dunnand, E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Burns, Patricia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Binetti, Ana Griselda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Forzani, Liliana Maria. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina Fil: Reinheimer, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Vinderola, Celso Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The ability of the adjunct culture Lacticaseibacillus paracasei 90 (L90) to prevent undesired eye formation by heterofermentative bacteria was assessed in soft cheeses, ripened either in normal conditions or with interruptions in the cold chain. Leuconostoc mesenteroides D11 isolated from defective cheeses with undesired eye production were added to control (C) and experimental (E) Cremoso soft cheeses to simulate the occurrence of high levels of adventitious heterofermentative bacteria; the adjunct culture L90 was added only to E cheeses. The presence of high levels of L90 affected the carbohydrates fermentation, and the levels of hippuric and benzoic acids. These changes produced an adverse environment for the undesirable activity of the strain D11. In effect, the incorporation of L90 decreased the metabolic activity of the D11 strain and consequently avoided the unwanted eye formation. The maintenance of an adequate cold chain was also an important factor to obtain cheese without eye defects.

Fil: Venica, Claudia Ines. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Santa Fe. Instituto de Lactologia Industrial. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Instituto de Lactologia Industrial; Argentina

In this work, we simulated cold chain interruptions in soft cheeses of high-moisture toassess their impact on ripening, putting attention on the behaviour of an adjunct cultureof Lactobacillus paracasei 90 (L90) when it was added. Temperature variation did notchange starter culture levels but it significantly increased L90 population at 60 days incheeses with cold chain interruption. Cold chain interruptions and adjunct culture led toan increase of the proteolysis levels and produced changes in the carbohydratefermentation, volatile compounds profiles and sensory scores. In cheeses with coldchain interruptions, L90 did not cause any defects and maintained its capacity ofimproving flavour and odour intensities by increasing the levels of diacetyl and acetoin,and decreasing pungent taste and compounds associated with rancidity. In addition,samples with adjunct culture presented increased levels of lactic acid without beingperceived as a defect by the sensory panel. Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Costabel, Luciana Maria. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Audero, Gabriela María de Luján. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Ale, Elisa Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Binetti, Ana Griselda. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Cuatrin, Alejandra Lorena. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Nieto, Ivana. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The interest of consumers in preserving health and increasing their quality of life through an appropriate diet has grown steadily since the turn of the century. A considerable corpus of research has focused on new functional foods. Among them, fermented milk-based beverages were the first developed and most marketable. Milk-based fermented beverages are valuable and versatile due to their safety, shelf stability, nutritional value, and sensory properties, and they certainly offer a delivery system for a diversity of functional principles. New generation products have been successfully developed through intervention in the traditional fermentation or manufacture processes to include live microorganisms, such as probiotics, and bioactive compounds such as prebiotics, lipids, peptides, or antioxidants. This chapter reports the current knowledge on the technological approaches applied to obtain functional milk-based beverages, with special emphasis in the more recent technologies and focus on the quality and functional properties of the products. Results obtained by our research group are included.

The aim of this study was to isolate, identify and characterize lactic acid bacteria (LAB) from spontaneously fermented maize silage, and evaluate their performance as spray-dried (SD) cultures to enhance the fermentation and the aerobic stability of maize micro-silos. Eleven strains of LAB were characterized for growth kinetics, the capability to grow in vegetable-based medium (VBM), production of organic acids and the ability to tolerate heat–stress. Three strains (Lactobacillus plantarum Ls71, Pediococcus acidilactici Ls72, and Lactobacillus buchneri Ls141) were selected and further characterized for the ability to grow as single strain or in co-culture in MRS and VMB medium, to survive at freeze and spray-drying process, for their performance as SD bacteria in micro-silos and for the aerobic stability in bucket silos. L. buchneri Ls141 showed the highest growth capability in VBM and produced the highest amount of acetic acid, while L. plantarum Ls71 produced the highest amounts of lactic acid. P. acidilactici Ls72 was the most heat-resistant strain, with a reduction of 0.2 log10 CFU/mL (15 min at 55°C). The three strains satisfactorily tolerated both spray and freeze-drying. After 4 days of fermentation, all the samples reached a pH value of about 3.7–3.8. A significantly lower cell load of filamentous fungi and yeasts (< 3 log10 CFU/g) and a higher concentration of total LAB (> 8.7 log10 CFU/g) was observed after 30 days of fermentation. A greater amount of acetic acid, crude protein, ash and ammonia nitrogen/total nitrogen was detected in inoculated silages. A significant reduction of filamentous fungi and yeasts was also observed in inoculated bucket silos after 50 d of fermentation. The aerobic stability was significantly improved in inoculated silage since the temperature remained stable after 16 days (384 h). On the contrary, an increase of 5°C was observed in control samples after 1 day. The selected strains have the potential to be produced as SD silage inoculant as they were able to accelerate the fermentation process, to control filamentous fungi and yeasts, to improve some nutritional and chemical parameters of silage and to improve aerobic stability. Fil: Burns, Patricia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Borgo, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Binetti, Ana Griselda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Puntillo, Melisa Anahí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Páez, Roxana. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Mazzoni, Rodolfo. Fragaria Srl; Argentina Fil: Reinheimer, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Vinderola, Celso Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The carbohydrate composition of the milk base plays a crucial role in the fermentation process of yogurt. In this study we investigate the effect of the traditional (TRAD) and delactosed (DEL) milks, added or not sucrose (S) in yogurt making, on the physicochemical parameters, growth of cultures and the formation of organic acids and volatile compounds during fermentation and storage. Yogurts made with delactosed milk had a delay in the fermentation up to 30 min in reaching the final pH and a slight minor postacidification, in comparison to yogurts prepared from traditional milk. Sucrose addition decreased the fermentation time in delactosed products. These observations were not accompanied by a significant change in the counts of thermophilic streptococci and thermophilic lactobacilli bacteria. The most notable differences in volatile compounds profiles were recorded in DEL + S respect to the remaining yogurts. The highest levels of diacetyl, 2,3-pentanedione, ethanol and ethyl esters found in DEL + S yogurts could be correlated with the higher glucose content, the main precursor of these compounds. Fil: Vénica, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Suárez, Viviana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

In the present work, it was studied the influence of brine concentration on the ripening of an Argentinean sheep cheese. The aim was to establish the conditions of the salting process for it to lead to a product with good quality and acceptability by consumers. Sheep cheeses were manufactured using a direct-vat-set culture of Streptococcus thermophilus as starter and chymosin as coagulant. The salting was carried out using brine with the following concentrations: 20, 15, 10 and 5% (w/v). The cheeses were vacuum packed on the fourth day and ripened for 60 days. In order to evaluate the influence of salt content in brine on cheese quality, there were analyzed gross composition, pH, microbial counts, proteolysis, sodium and calcium concentration, melting capacity and sensory characteristics. The increase of salt concentration in brine corresponded with a decrease in moisture as proteolysis advanced. This suggests some inhibition of proteolytic and peptidolytic enzymes involved in ripening due to these adverse environmental conditions. In the descriptive sensory analysis, differences were only found for bitter taste, which was significantly higher for the less salted cheeses. This was attributable and correlated with an increase in concentration of hybrophobic peptides due to an imbalance in proteolysis/peptidolysis during ripening. The melting capacity of the cheese was not affected by the level of salt used. Therefore, it is proposed that the salting process for an Argentinean sheep cheese should be with a 15% brine. Fil: Cuffia, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

In this work, we studied the influence of the type of coagulant enzyme and the curd scalding temperature on the proteolysis and residual coagulant and plasmin activities of a cooked cheese, Reggianito, in the interest of reducing ripening time. A two-factor experimental design was applied in two levels: type of coagulant enzyme, bovine chymosin or camel chymosin, and curd scalding temperature, 50 or 56 °C. The experimental treatments were applied in Reggianito cheese making experiments, and the samples were ripened for 90 d at 12 °C. Scalding temperature influenced residual coagulant activity; the cheeses cooked at 50 °C had significantly higher activity than those treated at 56 °C. In contrast, scalding temperature did not modify plasmin activity. Proteolysis was primarily affected by curd cooking temperature because chymosin-mediated hydrolysis of αs1 casein was slower in cheeses treated at 56 °C. Additionally, the nitrogen content in the cheese soluble fractions was consistently lower in the cheeses scalded at 56 °C than those cooked at 50 °C. A significant influence of the type of coagulant enzyme was observed, especially in the nitrogen fractions and peptide profiles, which demonstrated that camel chymosin was slightly less proteolytic; however, these differences were lower than those caused by the scalding temperature. Fil: Costabel, Luciana Maria. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Pozza, Leila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Cuffia, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The experiments reported in this research paper describe the effects of β-galactosidase enzyme dose and cheese whey amount, on the maximum concentration and yield of galacto-oligosaccahride (GOS) and reaction time. The experimental plan was based on central composite rotational design (CCRD) and modelled by response surface methodology (RSM). The results indicate that the proposed mathematical models could adequately describe the concentration and yield of GOS and the reaction time within the limits of the factors that are being investigated. The variance analysis shows high values of coefficients of determination (>0.97) while no significant lack of fit was evident. Hence, the models could be employed to select reaction conditions applied in the manufacture of products enriched in bioactive compounds with high value-added. Fil: Vénica, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Spray-drying of lactic cultures provides direct-to-vat starters, which facilitate their commercialization and use. However, this process may alter the metabolic activity and deteriorate technological features. In this work, we assessed the influence of spray-drying on the survival and aroma production of two strains of mesophilic lactobacilli: Lactobacillus paracasei 90 and Lactobacillus plantarum 91, which have already been characterized as good adjunct cultures. The spray-drying was carried out using a laboratory scale spray and the dried cultures were monitored during the storage for the survival rate. The dried cultures were applied to two cheese models: sterile cheese extract and miniature soft cheese. The influence on the carbohydrate metabolism and the production of organic acids and volatile compounds was determined. Both strains retained high levels of viable counts in the powder after drying and during the storage at 5 °C for twelve months. In addition, they also remained at high level in both cheese models during incubation or ripening. Similar profiles of carbohydrate fermentation and bioformation of volatile compounds were observed in the cheese extracts for each of the strains when tested as both fresh and dried cultures. In addition, the ability of Lb. paracasei 90 to increase the production of acetoin and diacetyl remarkably in cheese models was also confirmed for the spray-dried culture. Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Audero, Gabriela. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Paez, Roxana. Instituto Nacional de Tecnología Agropecuaria; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Fil: Oliszewski, Ruben. Universidad Nacional de Tucuman. Facultad de Agronomia y Zootecnia; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Lactobacillus fermentum Lf2, an autochthonous strain isolated as a non starter culture in Cremoso cheese, produces high EPS levels (~ 1 g/L) in optimized conditions (SDM broth, pH 6.0, 30 °C, 72 h). Technological (texture profile and rheological analysis) and sensory properties of non-fat yogurts with 300 and 600 mg EPS/L were studied at 3 and 25 days after manufacture. Yogurts with different EPS concentrations showed higher hardness values than the control group at both periods of time, being the only significant difference that remained stable during time. The consistency index was also higher for the treated samples at both times evaluated, being significantly different for samples with 300 mg/L of EPS extract, while the flow behavior index was lower for EPS-added yogurts. The thixotropic index was lower (P

Many studies about influence of Lactococcus lactis on cheese flavour have been reported, while the impact of mesophilic lactobacilli and Streptococcus thermophilus, either as single or mixed cultures, have been less studied. The ability of Lactobacillus paracasei 90, Lb. casei 72 (INLAIN collection) and Streptococcus thermophilus 2 (commercial strain) to produce flavour-related biochemical changes, as single or mixed (lactobacilli + streptococci) cultures, was assessed in a cheese model. These three strains, with different activities of glutamate dehydrogenase (GDH) and aminotransferases (AT), were incubated (14d/37 ºC) alone or in mixed cultures in a cheese model consisting of a sterile extract of a fresh cheese. Mesophilic lactobacilli showed fermentation of carbohydrates, an increase of peptidolysis and production of volatile compounds that were correlated with their AT activities. In addition, thesestrains also produced completely different profiles of the amino acceptor compounds: pyruvate and α-ketoglutarate. S. thermophilus 2 increased the level of α ketoglutarate due to its high GDH activity, but its ontribution to flavour compound production was negligible; Virtually no small additional hanges existed when S. thermophilus 2 was mixed with the lactobacilli. Biochemical changes leading to flavour formation were mainly due to the activity of lactobacilli. Our results suggest hat the AT profile and the peptidolytic activity of each strain influenced the volatilome of the extracts during incubation. So, both lactobacilli strains could be used as adjunct cultures in cheeses to increase/diversify the flavour, but more studies are needed to deepen the knowledge about the potential of S. thermophilus 2 for the production of flavour compounds. Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The application of high hydrostatic pressure (HHP) treatment has been proposed to reduce the ripening time of cheese via modifications in the enzymatic activities or the substrate reactivity. Investigations on the effect of HHP on cheese proteolysis have been undertaken with either encouraging results or little effect according to the treatment conditions and the type of cheese, but information concerning the effect of HHP on the ripening of hard cooked cheese is still lacking. In this report, we describe the effect of HHP treatment on Reggianito cheese proteolysis. For that purpose, 1-d-old miniature cheeses (5.5-cm diameter and 6-cm height) were treated at 100 or 400 MPa and 20°C for 5 or 10 min, and control cheeses in the trial were not pressurized. All cheeses were ripened at 12°C during 90 d. The HHP did not affect gross composition of the cheeses, but microbial load changed, especially because the starter culture count was significantly lower at the beginning of the ripening of the cheeses treated at 400 MPa than in controls and cheeses treated at 100 MPa. Cheeses treated at 400 MPa for 10 min had significantly higher plasmin activity than did the others; the residual coagulant activity was not affected by HHP. Proteolysis assessment showed that most severe treatments (400 MPa) also resulted in cheeses with increased breakdown of αS1- and β-CN. In addition, nitrogen content in soluble fractions was significantly higher in cheeses treated at 400 MPa, as well as soluble peptides and free AA production. Peptide profiles and individual and total content of free AA in 60-d-old treated cheese were as high as in fully ripened control cheeses (90 d). Holding time had an effect only on pH-4.6-soluble nitrogen fraction and plasmin activity; cheese treated for 10 min showed higher values than those treated for 5 min, at both levels of pressure assayed. We concluded that HHP treatments at 400 MPa applied 1 d after cheesemaking increased the rate of proteolysis, leading to an acceleration of the ripening process in Reggianito Argentino cheese, whereas 100-MPa treatments did not lead to significant changes. EEA Rafaela Fil: Costabel, Luciana Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. Grupo Calidad de Leche y Agroindustria; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Vaudagna, Sergio Ramon . Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnica; Argentina Fil: Cuatrin, Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. Grupo Calidad de Leche y Agroindustria; Argentina Fil: Audero, Gabriela Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. Grupo Calidad de Leche y Agroindustria; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina

In recent years, there has been an increase in the production of sheep milk in our country, which has been used mainly in cheese-making. This production, however, is not well standardised, as there are neither defined protocols nor well-characterised products for this procedure. Previously, different methodologies for making two types of sheep cheeses were developed at our institute. In the present work, the levels of free amino acids, organic acids, free fatty acids and volatile compounds for these sheep cheeses were studied in order to thoroughly characterise them. Therefore, we have produced two types of cheeses: one using a starter of Streptococcus thermophilus, in which the curd was cut into 5-mm pieces, washed and then heated to 43 ◦C (S cheeses); the other one using a mixed starter composed of S. thermophilus, Lactobacillus helveticus and Lactobacillus bulgaricus, in which the curd was cut into smaller pieces, was not washed and was heated to 47 ◦C (L cheeses). These cheeses were analysed at 2 and 180 days of ripening. Free amino acids (FAAs) and organic acids were studied by HPLC, free fatty acids (FFAs) were quantified by GC and volatile compounds were analysed by SPME-GC-FID/MS. The concentrations of all FAAs were significantly higher in the L cheeses than in the S cheeses, and this was evident from the beginning of the ripening. Both types of cheeses showed similar changes in the concentrations of some FAAs during ripening, but S cheeses were characterised by higher percentages of Phe, Leu and Val, while L cheeses had higher percentages of Pro, Ile, His and Asp. Lactic and citric acid were the most important organic acids present in both types of cheeses. At the end of the ripening, L cheeses presented higher levels of succinic and formic acids, while S cheeses showed a much higher amount of acetic acid. The levels of FFAs increased during ripening, and myristic, palmitic, stearic and oleic acids were the most abundant ones in both types of cheeses. L cheeses showed significantly higher levels of all FFAs at the end of the ripening and presented a greater increase in the percentages of short-chain fatty acids during ripening compared to S cheeses. Regarding volatile compounds, higher levels of aldehydes and ketones characterised the L cheeses, whereas S cheeses had higher proportions of esters and alcohols. Both types of cheeses presented similar areas in the most compounds of acids group, but the levels of butanoic and hexanoic acids were significantly higher in S cheeses than in L cheeses. The results of the present work offer an important contribution to this field: they have provided a better understanding of the changes that occur during the ripening of the two sheep cheeses manufactured with technologies developed in our group. These technologies could also be used by small sheep farm producers located in our region with the aim of increasing the economic yield of their products. Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The influence of three probiotic strains (Lactobacillus acidophilus, Lactobacillus paracasei and Bifidobacterium lactis) in semi-hard cheese proteolysis patterns was assessed. Probiotics were inoculated both as single cultures and as a three-strains mix, and added to milk by two different techniques: after a pre-incubation step or directly to vat. B. lactis did not show any effect on proteolysis of cheeses, while L. paracasei showed a little impact at the end of the ripening. On the contrary, L. acidophilus significantly influenced secondary proteolysis from the beginning of ripening, causing an increase in the levels of small nitrogen-containing compounds and free amino acids and changes in the peptide profiles. Lactobacillus acidophilus effect on peptidolysis was more noticeable when it was added to cheese-milk after pre-incubation in an enriched milk-fat substrate. Similar results obtained with the three-strain mixed culture suggest that L. acidophilus played a major role in secondary proteolysis of probiotic cheeses in this trial. Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Palma, Susana Beatriz. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Sabagg, Nora. Univ.nac del Litoral-fac de Ing.qca-instituto Tecnologi; Argentina Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Galacto-oligosaccharides (GOS) have interest in the food industry due to their recognized functional properties. In this work, we studied the effect of a commercial β-galactosidase enzyme from Kluyveromyces lactis (YNL-2, GODO) and Lactobacillus acidophilus La-5, on GOS formation during the manufacture and storage of drinkable and stirred yogurts. In a preliminary step, GOS synthesis and lactose hydrolysis by β-galactosidase was evaluated at different initial lactose concentrations and doses of enzyme. The GOS formation was favored with increasing of lactose concentration and enzyme doses, while the hydrolysis dominated at lower level of lactose. In turn, the presence of GOS was already evident at 45min of fermentation in yogurts with addition of β-galactosidase. Mean concentrations were 0.36 and 0.62g/100g for fresh drinkable and stirred yogurts, respectively. No changes in the GOS levels were observed through storage, indicating that they were stable in the products. The probiotic bacteria added were not able to produce GOS. The diminution of lactose was significant in yogurts with β-galactosidase; contents of residual lactose were around 1.3g/100g. We obtained different varieties of reduced-lactose yogurts enriched in galacto-oligosaccharides. The presence of probiotic and prebiotic would increase the functional properties of yogurts. Fil: Vénica, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Rebechi, Silvina Roxana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The aim of this work was to study the influence of different cheese-making technologies applied for three varieties of Argentinean cheeses on the action of coagulant enzyme, plasmin-plasminogen system and proteolysis. For this, Cremoso (soft cheese), Pategrás (semi-hard cheese) and Reggianito (hard cooked cheese) cheeses were analyzed for composition, nitrogen fractions, enzymes activities and elecrophoresis throughout ripening. As for coagulant, no reactivation of the enzyme was registered during ripening. Changes were mainly related to cooking temperature, as decreasing cooking temperature increased coagulant activity, being superior in Cremoso, followed by Pategrás and then by Reggianito cheeses. In regards of plamin/plasminogen system, it was observed greater activity of inactive plasminogen in Reggianito and Cremoso cheeses; while in Pategrás cheese the level was very low probably because plasminogen activation was enhanced during cheese making by the elimination of plasminogen activators inhibitors by curd washing. Indeed, the highest plasmin activity was found in Pategrás cheese, which indicates that curd washing combined with soft thermal treatment of the curd favored plasminogen activation. However, the environment defined by Reggianito cheese matrix was more suitable for maintaining the stability of plasmin activity along ripening. Results were consistent with proteolysis registered in electrophoresis and nitrogen fractions. Fil: Vélez, María Ayelén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Ramonda, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Aminotransferases and glutamate dehydrogenase are two main types of enzymes involved in the initial steps of amino acid catabolism, which plays a key role in the cheese flavor development. In the present work, glutamate dehydrogenase and aminotransferase activities were screened in twenty one strains of lactic acid bacteria of dairy interest, either cheese-isolated or commercial starters, including fifteen mesophilic lactobacilli, four thermophilic lactobacilli, and two streptococci. The strains of Streptococcus thermophilus showed the highest glutamate dehydrogenase activity, which was significantly elevated compared with the lactobacilli. Aspartate aminotransferase prevailed in most strains tested, while the levels and specificity of other aminotransferases were highly strain- and species-dependent. The knowledge of enzymatic profiles of these starter and cheese-isolated cultures is helpful in proposing appropriate combinations of strains for improved or increased cheese flavor. Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Two probiotic strains, Lactobacillus acidophilus and Lactobacillus paracasei subsp. paracasei, were used as adjunct cultures in semi-hard cheesemaking experiments, in order to study their influence on proteolysis during ripening. Cheeses with and without probiotic bacteria were manufactured. The population of probiotics remained above 107 cfu g−1 during all ripening, and they did not influence primary proteolysis. However, L. acidophilus produced a significant increase in the level of low molecular weight nitrogen compounds and individual free amino acids; the amino acid profiles were also different. Multivariate analysis of peptide profiles showed that samples were grouped mainly by ripening time, although the impact of probiotics was also noticeable. L. acidophilus showed a clear influence on secondary proteolysis, while a minor effect of L. paracasei was evidenced at the end of the ripening. These results showed that the tested strains influenced distinctly proteolysis of cheeses, probably as a consequence of their different proteolytic systems and their activity via the alimentary matrix (cheese).

Two strains of probiotic bacteria, one of Lactobacillus acidophilus and the other of Lactobacillus paracasei subsp. paracasei, were tested as adjunct cultures in cheese-making experiments, in order to assess their viability during cheese-making and ripening. The adjunct culture was added to cheese-making milk following two different methodologies: as a lyophilized powder dispersed in milk, or within a substrate composed of milk and milk fat. In all cheeses, probiotic bacteria increased a log cycle during cheese-making, and remained almost constant during ripening (60 days), always in higher number than required to meet probiotic standards. Gross composition of the cheeses was not affected by the addition of probiotic bacteria, except for pH value: cheeses with L. acidophilus added within the pre-incubated substrate, had lower pH values and were over acidified and crumbly. Direct addition of the probiotic culture was the methodology with the best performance; however the pre-incubation presented some advantages such as an increased population of lactobacilli in the initial inoculum. Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Quiberoni, Andrea del Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Suárez, Viviana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Reggianito Argentino cheese is traditionally manufactured with whey starter cultures that provide typical and intense flavor but can cause poor quality standardization. In this study, the influence of natural and selected starters on Reggianito Argentino cheese proteolysis was investigated. Cheeses were manufactured with three strains of Lactobacillus helveticus (SF133, SF138 and SF209) cultured individually in sterile whey and used as single or mixed starters. Control cheeses were made with natural whey starter culture. Cheeses were analyzed to determine gross composition, as well as total thermophilic lactic flora. Proteolysis was assessed by N fractions, electrophoresis and liquid chromatography. Gross composition of the cheeses did not significantly differ, while viable starter cell counts were lower for cheeses made with strain SF209 alone or combined with other strains. Soluble N at pH 4.6 was the same for cheeses made with natural or selected starters, but soluble N in 12% trichloroacetic acid and 2.5% phosphotungstic acid was significantly higher in cheeses made with starters containing strain SF209. Nitrogen fractions results indicated that natural whey starter cultures could be replaced by several starters composed of the selected strains without significant changes to proteolysis patterns. Starter cultures prepared only with SF209 or with the three selected L. helveticus strains produced cheese products with significantly more proteolysis than control cheeses. Chromatographic profiles analyzed by principal components showed that three main peaks on chromatograms, presumptively identified as Tyr, Phe, and Trp, explained most of variability. Principal component scores indicated that cheese samples were grouped by ripening time, which was confirmed by linear discriminant analysis. On the contrary, samples did not cluster by Lactobacillus strain or type of starter. Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Suárez, Viviana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

The composition of the dairy matrix used in yogurt manufacture could influence the metabolic activity of yogurt starter and the compounds produced during fermentation. In this way, the lactose hydrolysis with a β-galactosidase enzyme and the supplementation with dairy powders to obtain different types of delactosed yogurts for lactose-intolerant people modifies the milk base composition.In this work, we studied the influence of the addition of different doses of β-galactosidase and levels of dairy powders on organic acids profile during the manufacture and storage of two varieties of yogurt (natural and sweetened).Lactose, glucose, galactose, titratable acidity, fermentation time, and microbiological counts were also evaluated. The mean proportions of lactose/glucose/galactose in relation to the total sugars were 18:36:46 in hydrolyzed yogurts, while they were 81:4:15 in unhydrolyzed ones. In supplemented yogurts, the content of lactose, citric, orotic, and hippuric acids were significantly increased. The starter population was similar in all yogurts, but some changes in their activity were evidenced due to both factors studied. The fermentation time was slightly increased, and the lactic acid content and the titratable acidity were significantly increased due to fortification while they were decreased by enzyme addition. These results are probably due to the increase in the buffer properties of the milk base by the dairy powder addition and due to an inhibition of the starter activity caused by changes in the carbohydrate profile. The results demonstrated that the changes in the matrix composition of the yogurt affected the organic acids profile, above all the lactic acid content. Fil: Vénica, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Selected strains of mesophilic lactobacilli with key enzymatic activitiesmay be employed to intensify or diversify cheese flavor during ripening. Among enzymes of interest, aminotransferases are most important, as they are involved in the first step of amino acid (AA) catabolism. In previous studies, Lactobacillus paracasei I90 has been shown to increase both the secondary proteolysis in soft and semihard cheeses and the production of volatile compounds in minisoft cheeses. In this work, its potential for the formation of volatile compounds derived from AA catabolism was assessed by solid-phase microextraction coupled to GC-FID/MS in a hard-cooked cheese model, consisting of a cheese extract sterilized by filtration. Lb. paracasei I90 showed aminotransferase activity towards all the AAs studied (branched-chain AAs, aromatic AAs, aspartic acid, and methionine). The highest levels were observed for aspartic acid, followed by branched-chain AAs and tryptophane. Among the volatile compounds derived from AAs, 2-methylbutanal, 3-methylbutanal, diacetyl, 3-methyl1-butanol, acetic, and 3-methylbutanoic acids were detected at higher level in extracts inoculated with Lb. paracasei I90 than in controls. It was concluded that the production of volatile compounds by Lb. paracasei I90 in a hard cheese model was consistent with its main aminotransferase activities, making this strain a good candidate for enhancing flavor in hard cheeses. Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina Fil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina

Reduced-lactose yogurts are still not available in the Argentinean market despite the fact in Latin America the incidence of deficientlactose individual is very high. In this work, variables to hydrolyze the lactose (three levels of β-galactosidase enzyme and the time of its addition) were evaluated during manufacture of natural and sweetened (8% p/v) drinkable yogurts. Experimental yogurts (with enzyme) were compared with controls (without enzyme). The evolution of lactose content, pH, titratable acidity and syneresis were analyzed during 28 days of storage at 5ºC. Results showed feasibility in the simultaneous addition of enzyme and starter. The hydrolysis percentages in experimental yogurts ranged from 74 to 93% at the end of manufacture and stayed without changes during storage. For control yogurts, the lactose content decreased approximately 15%, which was doubled at 14 days. The inclusion of sucrose did not substantially affect the hydrolysis process. After 14 days, the pH and acidity in experimental yogurts were slightly higher and lower, respectively, in comparison to controls. On the other hand, the sensory panel found that the reduced-lactose and traditional yogurt where similar. Fil: Vénica, Claudia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Lactologia Industrial; Argentina; Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Lactologia Industrial; Argentina; Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Lactologia Industrial; Argentina; Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Santa Fe. Instituto de Lactologia Industrial; Argentina

In this work, we studied the growth, survival and peptidolytic activity of Lactobacillus plantarum I91 in a hard-cheese model consisting of a sterile extract of Reggianito cheese. To assess the influence of the primary starter and initial proteolysis level on these parameters, we prepared the extracts with cheeses that were produced using two different starter strains of Lactobacillus helveticus (Lh138 or Lh209) at three ripening times: 3, 90 and 180 days. The experimental extracts were inoculated with Lb. plantarum I91; the control extracts were not inoculated, and the blank extracts were heat-treated to inactivate enzymes and were not inoculated. All extracts were incubated at 34ºC for 21 days, and then the pH, microbiological counts and proteolysis profiles were determined. The basal proteolysis profiles in the extracts of young cheeses made with either strain tested were similar, but many differences between the proteolysis profiles of the extracts of the Lh138 and Lh209 cheeses were found when riper cheeses were used. The pH values in the blank and control extracts did not change, and no microbial growth was detected. In contrast, the pH value in experimental extracts decreased, and this decrease was more pronounced in extracts obtained from either of the young cheeses and from the Lh209 cheese at any stage of ripening. Lb. plantarum I91 grew up to 8 log during the first days of incubation in all of the extracts, but then the number of viable cells decreased, the extent of which depended on the starter strain and the age of the cheese used for the extract. The decrease in the counts of Lb. plantarum I91 was observed mainly in the extracts in which the pH had diminished the most. In addition, the extracts that best supported the viability of Lb. plantarum I91 during incubation had the highest free amino acids content. The effect of Lb. plantarum I91 on the proteolysis profile of the extracts was marginal. Significant changes in the content of free amino acids suggested that the catabolism of free amino acids by Lb. plantarum I91 prevailed in a weakly proteolysed medium, whereas the release of amino acids due to peptidolysis overcame their catabolism in a medium with high levels of free amino acids. Lb. plantarum I91 was able to use energy sources other than lactose to support its growth because equivalent numbers of cells were observed in extracts containing residual amounts of lactose and in lactose-depleted extracts. The contribution of Lb. plantarum I91 to hard-cooked cheese peptidolysis was negligible compared to that of the starter strain; however, its ability to transform amino acids is a promising feature of this strain. Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Peralta, Guillermo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Milesi, Maria Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Hard cooked cheeses are mostly manufactured with lactic starters of Lactobacillus helveticus, which constitute a major proteolytic agent in the food. In this work, we assessed the proteolysis produced by enzymes of two strains of Lactobacillus helveticus in a sterile substrate prepared with hard-cooked cheeses, and identified the time of ripening when main changes in proteolysis are produced. The extract, a representative model of the aqueous phase of the cheeses, was obtained from Reggianito cheeses of different ripening times (3, 90 and 180 days) made with starters composed of the strains tested, either SF138 or SF209. To obtain the substrate, the cheese was extracted with water, substrates were incubated at 34ºC during 21 days; samples were taken at 0, 3, 7, 14 and 21 days. Sterility was verified by plating samples on APC agar and incubating at 37ºC for 48 h. Proteolysis was determined by liquid chromatography of soluble peptides and free amino acids. Great variation in peptide profiles was found as incubation progressed in cheese extracts, which evidenced that proteases and peptidases from the starter were active and able to degrade the proteinaceous material available in the extracts. The extracts derived from cheeses with L. helveticus SF138 showed low production of peptides and a notable increase in free amino acids content during incubation. L. helveticus SF209, on the contrary, caused an increase on soluble peptides, but the free amino acids accumulation was lower than in the first case, which suggested that L. helveticus SF209 had either a low peptydolitic activity or produced an intense amino acids breakdown. This trend was more evident for extracts prepared with 90-d-old cheeses. It was concluded that the strains of L. helveticus assayed showed potentially complementary proteolytic abilities, as SF209 was able to provide a continuous replenishment of peptides during incubation, while SF138 increased their hydrolysis to free amino acids. The extract was an appropriate medium to model hard cooked cheese ripening in short periods of time. Fil: Milesi, Maria Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

U radu su proučeni profili proteolize u argentinskom ovčjem siru napravljenim dvjema metodama proizvodnje kako bi se dobile tipične i definirane karakteristike. Proizvedeni su sirevi s mikrobnom kulturom Streptococcus thermophilus (S-sirevi) i sirevi s miješanom mikrobnom kulturom Streptococcus thermophilus i Lactobacillus bulgaricus (L-sirevi). Sirevi su dozrijevali na 12oC i 80% relativne vlažnosti kroz 180 dana i uzorci su uzimani tijekom tog vremenskog razdoblja. Rezultati pokazuju određene sličnosti ali i razlike, posebice u pH vrijednosti, dok je senzorska analiza pokazala bitne razlike između te dvije vrsta sireva. S-sirevi imaju niži stupanj proteolize i blaži okus, što ih čini prikladnim za konzumaciju nakon kratkog vremena dozrijevanja. L-sirevi imaju viši stupanj proteolize, te puno izraženija senzorska svojstva, što ih čini prikladnim za konzumaciju nakon duljeg vremena dozrijevanja., In this work the proteolysis profile of Argentinean sheep cheeses made by two production methods were studied in order to develop products with typical and defined features. Cheeses with a starter of Streptococcus thermophilus, (S-cheeses) and cheeses with a mixed starter of Streptococcus thermophilus and Lactobacillus bulgaricus, (L-cheeses) were manufactured. The cheeses were ripened at 12oC and 80% relative humidity for 180 days and samples were taken throughout this period. Results show similarities but also some differences, especially in pH value, while sensory evaluation indicated important differences between the two types of cheeses. S-cheeses had a low proteolysis and soft flavor, making them appropriate for consumption after a short ripening time. L-cheeses had a higher proteolysis level and more intense sensory characteristics, making them appropriate for consumption after a longer ripening time.

The individual contribution of six strains of probiotic bacteria (three of Lactobacillus acidophilus and three of the Lactobacillus casei group) to proteolysis patterns in a semi-hard cheese was assessed. Control cheeses (without probiotics) and two types of experimental cheeses (with the addition of probiotics either directly to milk or by a two-step fermentation method), were manufactured. Cheeses containing L. acidophilus showed the most extensive peptidolysis, which was evidenced by changes in the peptide profiles and a noticeable increase of FAA, in comparison to control cheeses. The strains of the L. casei group showed a lower contribution to cheese peptidolysis, which consisted mainly of FAA increase. Two-step fermentation improved peptidolytic activity only for one of the cultures of L. acidophilus tested. The addition of L. acidophilus strains into cheese may be suitable not only for their beneficial health effect but also for their influence on secondary proteolysis, consistent with acceleration of ripening and improved flavor formation. Fil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina Fil: Candioti, Mario César. Universidad Nacional del Litoral; Argentina Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina