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The purpose of this research was to evaluate the potential of a sourdough containing cricket powder hydrolysate by the RO25 Yarrowia lipolytica strain to produce an innovative bakery product. RO25 hydrolysed cricket bread (RO25H-CB) was compared with control bread obtained from a traditional sourdough using wheat flour and with an additional bread control obtained from no-hydrolysed cricket powder sourdough. The results obtained showed that RO25H-CB had a highest amount of proteins and free fatty acids than wheat control bread, attributed to the well-known proteolytic and lipolytic activities of Y. lipolytica. Moreover, RO25H-CB sample was characterised by high content of health-promoting and aroma precursors lipids as well as a lowest biogenic amine index among samples analysed, suggesting for this sample a high overall quality respect to no hydrolysed cricket powder bread. Finally, the data relating the sensory analysis highlighted good application opportunities for RO25 cricket hydrolysate as ingredients for baking. In fact, RO25H-CB had received positive evaluations for almost all the parameters considered. These results demonstrated that hydrolysates from Y. lipolytica, compared to the no hydrolysed cricket, were able to impart specific sensory and qualitative characteristics to the final product, with positive feedback from the involved panellists.

The objective of this work was to compare goat cheeses obtained from milk previously subjected to high pressure homogenization (1000 bar) with those produced from untreated milk and milk subjected to sanitization (61 degrees C; 20 min) or to pasteurization (72 degrees C; 15 s). The pressure homogenization treatment had both direct and indirect effects on cheese characteristics and their evolution during ripening. The direct effects were principally linked to the change in water-binding capacity of proteins as shown also by the lower whey separation. The indirect effects involved the microbial growth or activity and, particularly, modifications of the population of the lactic acid bacteria that occurred naturally and their evolution as well as a more precocious yeast and mold growth with a consequent rapid rise in pH. Although the treatment proved to enhance both proteolytic and lipolytic activities according to Fourier transform infrared analysis, which was used to obtain a rapid description of the biochemical modification, the cheeses homogenized under high pressure showed relevant qualitative differences only in the zone corresponding to amide I and amide II signals of proteins. The activation of these enzymatic activities observed in the homogenized cheeses could be either an indirect effect of the shift of the microbial population or a consequence of a different exposure of the macromolecules to the enzymatic activity. Scanning electron microscopy analyses of goat cheeses revealed that cheeses homogenized under high pressure had a more homogeneous microstructure than did the others.

In this work a feasible application of the antifungal activity of the volatile metabolites produced by a strain of Rhizopus arrhizus has been investigated. The effect of such metabolic vapours, of their individual components, such as ethanol, isobutyl alcohol and 3-methyl butanol, or of their mixtures on Aspergillus flavus growth, both in semisynthetic media and miniaturized bread loaves, has been studied. The antifungal activity attributable to these primary metabolites, when present in the vapour phase at levels ranging between 3 and 6% (v/v of head space), was synergistically enhanced by a decrease of the aw in the food model systems. The physical state of the alcohols, i.e. their partition between solid and gaseous phases, also dependent on the aw of the system, seems to be one of the determinants for their antifungal activity.

Present study aimed to ascertain whether the combination of two factors, i.e., time of harvest and type of yeast, can significantly moderate the effect of climate change on Chardonnay wine composition. In this view, three Chardonnay musts obtained from grapes at different harvest date [technological maturity ‘as control’; delayed harvest; a mixture of ‘early (green) harvest’ with delayed harvest ‘as alternative approach’] and three selected yeast strains [Saccharomyces cerevisiae ‘as control’; hybrid Saccharomyces cerevisiae/Saccharomyces paradoxus; scalar alternative approach with Starmerella bacillaris and hybrid Saccharomyces cerevisiae/Saccharomyces paradoxus] were used to design and compare six different trials, replicated at pilot level (n. total fermentations: 18). Wines were evaluated in terms of sensory and chemical parameters (alcohol, acidity, organic acids, phenolic compounds and glycerol) and results tested by statistical analysis. Although the wine alcohol content decreased at the best by ~ 1.2% v/v, whereas the total acidity increased up to ~ 2.5 g/L, the results from sensory evaluation highlighted that the proposed ‘alternative approach’ may cause excessive acidity and bitterness perception, therefore, further deacidification and fining treatments may be needed. The present approach to reduce the alcohol content of wine and increase its total acidity is simple, inexpensive and applicable in all wineries.

Carvacrol, (E)-2-hexenal, and citral at sublethal concentrations combined with isothermal heating between 55 and 68°C were assessed for their effects on Listeria monocytogenes 56LY. Experimental survival curves were obtained and fitted to the Weibull equation to estimate parameters describing their shape and rate. These parameters were further used to assess the impact of this combination of treatments on the cell resistance distribution during inactivation. The sublethal concentrations of the aroma compounds used (i.e., 50 mg/liter citral, 65 mg/liter (E)-2-hexenal, and 30 mg/liter carvacrol) did not prevent the growth of L. monocytogenes at 37°C but did enhance inactivation. Between 55 and 63°C, the presence of the aroma compounds reduced by about two-thirds the time needed for a 5-log reduction of the microbial counts, e.g., from 145.75 h in the control treatment (at 55°C) to 40.84 h in the presence of carvacrol (at the same temperature). The mean and variance observed in the frequency distribution of resistance were reduced as the temperature increased. The results obtained at isothermal temperatures and with single aroma components provide basic information regarding components frequently found in essential oils, which can be used in combination with less extreme thermal treatments to provide energy conservation and improve food quality.

High-pressure homogenization (HPH) is one of the most promising alternatives to traditional thermal treatment of food preservation and diversification. Its effectiveness on the deactivation of pathogenic and spoilage microorganisms in model systems and real food is well documented. To evaluate the potential of milk treated by HPH for the production of Crescenza cheese with commercial probiotic lactobacilli added, 4 types of cheeses were made: HPH (from HPH-treated milk), P (from pasteurized milk), HPH-P (HPH-treated milk plus probiotics), and P-P (pasteurized milk plus probiotics) cheeses. A strain of Streptococcus thermophilus was used as starter culture for cheese production. Compositional, microbiological, physicochemical, and organoleptic analyses were carried out at 1, 5, 8, and 12 d of refrigerated storage (4°C). According to results obtained, no significant differences among the 4 cheese types were observed for gross composition (protein, fat, moisture) and pH. Differently, the HPH treatment of milk increased the cheese yield about 1% and positively affected the viability during the refrigerated storage of the probiotic bacteria. In fact, after 12 d of storage, the Lactobacillus paracasei A13 cell loads were 8 log cfu/g, whereas Lactobacillus acidophilus H5 exhibited, in P-P cheese, a cell load decrease of about 1 log cfu/g with respect to the HPH-P cheese. The hyperbaric treatment had a significant positive effect on free fatty acids release and cheese proteolysis. Also, probiotic cultures affected proteolytic and lipolytic cheese patterns. No significant differences were found for the sensory descriptors salty and creamy among HPH and P cheeses as well as for acid, piquant, sweet, milky, salty, creamy, and overall acceptance among HPH, HPH-P, and P-P Crescenza cheeses. 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: Patrignani, Francesca. University of Bologna. Dipartimento di Scienze degli Alimenti; Italia Fil: Serrazanetti, Diana Isabella. University of Bologna. Dipartimento di Scienze degli Alimenti; Italia 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 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: Lanciotti, Rosalba. University of Bologna. Dipartimento di Scienze degli Alimenti; Italia Fil: Guerzoni, Maria Elizabetta. University of Bologna. Dipartimento di Scienze degli Alimenti; Italia

The aim of this work was to analyse some quality parameters of Mytilus galloprovicialis harvested monthly in the period ranging from April 2002 and February 2003 in a longline off-shore mussel farm, located in the Adriatic Sea, near Cattolica (Emilia Romagna Region, Italy). After harvesting, the samples were analysed in order to determine the counts of fecal coliforms (FC) and Escherichia coli, the presence of Salmonella, as prescribed by Italian and European Community regulations, and other pathogens (Vibrio parahaemolyticus, Listeria monocytogenes), as well as the meat yield and its proximate composition, its Fe, Cr, Cd, Zn, Pb and Cu content, the total lipids of the meat and their specific composition. The results obtained evidenced that many of the parameters studied, i.e. the meat proximate composition, the lipid fatty acid composition and the microbiological indices, were subjected to seasonal fluctuations. In particular, the microbiological data showed that 4 mussel samples (June, December, January and February) out of 12 did not match the limit imposed by Italian law and Emilia Romagna protocol concerning the FC and E. coli counts. While L. monocytogenes and Salmonella spp. were never detected in all the samples analysed, three samples (April, January and February) were positive for the presence of V. parahaemolyticus. No seasonal fluctuations were evidenced for Fe, Cr, Cd, Zn, Pb and Cu contents, always under the limits imposed by Italian law.

The effects of the interaction between Saccharomyces cerevisiae LBS and Lactobacillus sanfranciscensis LSCE1 and of their responses to acid, oxidative or osmotic stress on alcohol and aroma production were assessed. The exposure of S. cerevisiae LBS and L. sanfranciscensis LSCE1 cells to oxidative, acid or osmotic sub-lethal stress gave rise to a common or specific responses. γ-decalactone, 2(5H)-furanones and aldehydes were overproduced by LAB following oxidative stress. The acid stress induced both in yeasts and LAB, as well as in their co-cultures, a relevant accumulation of isovaleric and acetic acids and higher alcohols. A cross-exposure of yeasts and LAB to their preconditioned media, generated in S. cerevisiae a release of esters including esters of long-chain unsaturated fatty acids coming from membrane phospholipids. These esters were excreted also by yeasts following a pressure stress.

High-pressure homogenization (HPH) has been proposed to be applied directly to lactic acid bacterial cells at sublethal levels to enhance some functional properties. As the principal target of HPH are the cell surface envelope structures, the aim of this work was to study the effect of a HPH treatment, applied at 50 MPa, on cell membrane stress responses of alreadyknown functional strains, isolated from Argentinean products. Specifically, the membrane fatty acid composition of cells before and after the sublethal treatment was investigated, and the results showed that plasma membranes, their level of unsaturation and their composition are involved in response mechanisms adopted by microbial cells when subjected to a sublethal HPH stress. In fact, the data obtained demonstrated that the treatment was able to modify the fatty acid profile of the different strains, although a uniform response was not observed. Further studies are necessary both to elucidate the role of each fatty acid in the cell response mechanisms and to clarify the changes in membrane compositions induced by HPH treatment also in relation to the applicative potential of this technique. Fil: Tabanelli, G.. Inter-Departmental Centre of Industrial Agri-Food Research (CIRI Agroalimentare); Italia Fil: Patrignani, Francesca. University of Bologna. Department of Agri-Food Science and Technologies, Alma Mater Studiorum; Italia Fil: Gardini, F.. Inter-Departmental Centre of Industrial Agri-Food Research (CIRI Agroalimentare); Italia. University of Bologna. Department of Agri-Food Science and Technologies, Alma Mater Studiorum; Italia Fil: Vinderola, Celso Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina Fil: Reinheimer, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentina. Universidad Nacional del Sur. Departamento de Ingenieria Quimica; Argentina Fil: Grazia, L.. Inter-Departmental Centre of Industrial Agri-Food Research (CIRI Agroalimentare); Italia. University of Bologna. Department of Agri-Food Science and Technologies, Alma Mater Studiorum; Italia Fil: Lanciotti, R.. Inter-Departmental Centre of Industrial Agri-Food Research (CIRI Agroalimentare); Italia. University of Bologna. Department of Agri-Food Science and Technologies, Alma Mater Studiorum; Italia

Low levels of High Pressure of Homogenization (HPH) can be applied directly to lactic acid bacteria cells in order to enhance some functional properties. In a previous work we observed that a 50 MPa HPH treatment increased Lactobacillus paracasei A13 hydrophobicity and resistance to simulated gastric digestion. The aim of this work was to assess the in vivo effects of HPH treatment applied to probiotic lactobacilli on their interaction capacity with the gut and on their ability to induce IgA cell proliferation in mice intestine. BALB/c mice received FITC-labelled cultures of strains, previously treated or not (control) at 50 MPa. Fluorescently labelled cells were studied in the intestine of animals sacrificed 10 and 30 min after intragastric intubation. HPH-treated and control cultures of each strain were orally administered to mice for 2, 5 or 7 consecutive days. The number of IgA-producing cells in the gut was studied by immunohistochemistry. HPH treated probiotic lactobacilli modified their interaction with the small intestine. HPH-treated cells induced a higher IgA response compared to untreated ones, in a strain- and feeding period-dependent way. HPH treatment could increase some in vivo functional characteristics of probiotic strains, highlighting the potential of this technique for the development of probiotic cultures.

Considerazioni circa gli aspetti microbiologici dei vegetali di IV gamma

The need to predict microbial behaviour has become pressing as the preservation techniques have become milder or shift ed to more ‘natural’ compounds. The past decade has been characterized by an increasing consumer demand for more natural-tasting food products, which means additive-free, fresher and minimally treated protocols but with a maintained microbiological safety (Gould, 1996). This trend has forced the search for new preservative techniques or for the combination of preservatives in the philosophy of the ‘Hurdle Technology’ concept in food safety proposed by Leistner (1995). The use of natural antimicrobial compounds and EOs, as preservation compounds, is thus of utmost interest in the food industry. An efficient exploitation of such compounds at the industrial level is still under study. To speed up this process, as well as to help in the scaling up of the usage of EOs in food, the predictive modelling approach can be seen as a useful tool. However, at present, few predictive models of EO-induced microbial inactivation can be found. Similarly, few works aiming to study the inhibitory eff ect of EOs or their constituents, in combination with other barrier factors such as temperature and pH, on microorganisms can be found.

High pressure homogenization (HPH) has been proposed as an effective alternative to high hydrostatic pressure in the continuous sanitization of fluid food systems. In this study, we evaluated the influence of HPH treatment, applied individually (one, two or three cycles) or in combination with other mild physical or chemical stresses (mild heat treatment H 2 O 2 and low pH), on the capability of Bacillus cereus and Bacillus subtilis spore, suspended in sterilized double distilled water, to form colonies. Although plate count only slightly decreased in all the strains when one cycle of HPH at 150 MPa was applied alone, the spores released significant levels of dipicolinic acid (up to 28%) that could indicate a possible disruption of spore layers. Three consecutive cycles of HPH determined high reduction of colony count (about 5 log CFU/ml) and high DPA release (52%). Among the stress conditions applied, it was observed that only the thermal shock after one HPH cycle reduced the colony count of 2.3 log CFU/ml and induced a DPA release up to 57%. These results suggested HPH as a novel application for B. cereus and B. subtilis control in fluid foods.

The aim of this study was the evaluation of the effects of pure citral and citron essential oil on microbial spoilage and growth and survival of pathogenic microorganisms during storage. They were added in the syrup of industrial ready-to-eat fruit salads stored at 9 degrees C. Both citral (25 to 125 ppm) and citron essential oil (300, 600, 900 ppm) were able to prolong the microbial shelf life of the fruit-based salads. The essential oil gave excellent results, avoiding the undesirable effects attributable to the cytotoxicity of citral. Citron essential oil doubled the time needed for the wild microflora to reach concentrations able to produce a perceivable spoilage in condition of thermal abuse (9 degrees C). The same essential oil had reduced effects on the survival of Gram-negative species Salmonella Enteritidis and Escherichia coli, but showed a strong inhibition toward the Gram-positive pathogen Listeria monocytogenes.

High pressure homogenization (HPH) is one of the most promising alternatives to traditional thermal treatment for food preservation and diversification. In order to evaluate de potential of milk treated by HPH for the production of fermented milks carrying probiotic bacteria, four types of fermented milks were manufactured (using Streptococcus thermophilus and Lactobacillus delbruekii subsp. bulgaricus as starters): HPH- (from HPH treated milk), P- (from pasteurized milk), HPH-P- (HPH treated milk plus probiotics) and P-P- (pasteurized milk plus probiotics) fermented milk. Microbiological, physicochemical and organoleptic analysis was carried out during the refrigerated period (35 d ) at 4ºC. The use of HPH applied to milk did not modify, with respect to the traditional products, the viability of the probiotic cultures whereas increased the cell loads of the starter cultures (ca. 1 log order). The coagula from HPH treated milk resulted significantly (P < 0.05) more compacted (higher firmness) than the one obtained with only pasteurized milk, and it was characterized by the highest values of consistency, cohesiveness and viscosity indexes with respect to the fermented milks produced from milk without HPH treatment. In relation to the sensory analysis, all the samples received high scores for each descriptor considered, and were judged then of presenting high quality. The HPH treatment of milk can have a potential of diversifying the market of probiotic fermented milks, especially in terms of texture parameters.

Novel non thermal processes represent an alternative to thermal treatment to improve quality, safety and functionality of milk and milk based products. Among to the alternatives proposed, the High Pressure Homogenization (HPH) is one of the most promising technology and its potential has been especially applied to the dairy field both for the milk decontamination and product diversification. The aim of the research, included in the European project “Innovative non thermal processing technologies to improve the quality and safety of ready-to-eat meals (HighQ RTE)”, was to evaluate the potential of HPH to inactivate pathogenic species such as Listeria monocytogenes and Salmonella enteritidis in raw milk and eggs and spoilage yeasts, Saccharomyces cerevisiae and Zygosaccharomyces cerevisiae, inoculated in vegetable and fruit juices. In addition, the effects of HPH were evaluated also on the organoleptic quality of milk, milk products and treated juices by using the GC-MS/SPME technique. Moreover also the modifications of viscosity in relation to the entity of the pressure treatment were studied. The data obtained were compared with those obtained using traditional heat treatments. The results regarding the milk decontamination showed that the inactivation curves of S. enteritidis were linear up to the 4th cycle at 100 MPa after which their slopes diminished. Also L. monocytogenes resulted to be sensitive to HPH. A reduction of 5 Log cfu/ml was obtained with 8 pressure pushes at 100 MPa. Concerning the yeast inactivation, the results obtained were very different in relation to the considered species and food matrix. Saccharomyces cerevisiae was very sensitive to HPH when inoculated in carrot juice. As far as viscosity modifications, the most interesting results were obtained for apricot and tomato juices, finding a positive relation with the increase of pressure up to the 5th cycle at 100 MPa.

In recent years, the interest in the possible use of natural alternatives to food additives to prevent bacterial and fungal growth has notably increased. Plants and plant products can represent a source of natural alternatives to improve the shelf-life and the safety of food. Some of these compounds, i.e. hexanal, hexanol, 2-(E)-hexenal and 3-(Z)-hexenol, produced throughout the lipoxygenase pathway have important roles in plant defence with a protective action towards microbial proliferation in wounded areas. Otherwise, hexanal and 2-(E)-hexenal have evidenced a marked antimicrobial activity against food spoilage and pathogenic microbial species both in model and real systems. The precise mechanisms of action of all these antimicrobial compounds are not yet clear. Because the usage of these compounds as antimicrobials in foods has to be supported by the comprehension of mechanisms of action of these compounds, the overall purpose of this work was to study the modifications of the cell membrane and volatile compounds of Listeria monocytogenes, Staphylococcus aureus, Salmonella enteritidis and Escherichia coli during the growth in the presence of sub-lethal doses of these two aldehydes. The results obtained evidenced that the tested molecules induced noticeable modifications of the composition of cell membrane and the volatile compounds produced during the growth. Although specific differences in relation to the species considered were identified, 2-(E)-hexenal and hexanal induced a marked increase of some membrane associated fatty acids, both linear and branched fatty acids as well as unsaturated fatty acids, and released free fatty acids.

Novel non thermal processes represent an alternative to thermal treatment to improve quality, safety and functionality of milk and milk based products. Among to the alternatives proposed, the High Pressure Homogenization (HPH) is one of the most promising technology and its potential has been applied to the dairy field both for the milk decontamination and product diversification. The aim of this research, included in the European project “Innovative non thermal processing technologies to improve the quality and safety of ready-to-eat meals (HighQ RTE)”, was to evaluate the potential of HPH to inactivate pathogenic species such as Listeria monocytogenes and Salmonella enteritidis in raw milk and to promote the proliferation and viability of probiotic bacteria inoculated in HPH processed milk. The data obtained were compared with those obtained using traditional heat treatment. The results regarding the milk decontamination showed that the inactivation curves of S. enteritidis were linear up to the 4th cycle at 100 MPa after which their slopes diminished. Also L. monocytogenes resulted to be sensitive to HPH. A reduction of 5 Log cfu/ml was obtained with 8 pressure pushes at 100 MPa. The use of HPH applied to milk increased the performance of the probiotic cultures co-inoculated and extended the product shelf-life during the refrigerated storage. The data obtained confirmed the industrial importance of this technology both for milk decontamination and optimization of probiotic fermented milks. In addition, the effect of HPH on the organoleptic quality of milk and milk products was evaluated in relation to sulfur and aroma compounds detected respectively by GC-FPD and GC-MS/SPME.

The aim of this research was the evaluation of the effects of milkfat content, nonfat milk solids content, and high-pressure homogenization on 1) fermentation rates of the probiotic strain Lactobacillus paracasei BFE 5264 inoculated in milk; 2) viability loss of this strain during refrigerated storage; and 3) texture parameters, volatile compounds, and sensorial properties of the coagula obtained. The data achieved suggested a very strong effect of the independent variables on the measured attributes of fermented milks. In fact, the coagulation times were significantly affected by pressure and added milkfat, and the rheological parameters of the fermented milk increased with the pressure applied to the milk for added nonfat milk solids concentrations lower than 3%. Moreover, the polynomial models and the relative response surfaces obtained permitted us to identify the levels of the 3 independent variables that minimized the viability loss of the probiotic strain used during refrigerated storage.

In recent year there has been an increasing demand for a new range of dairy product, including yoghurts, which are similar to traditional ones but have a low fat content. However low fat yoghurts has a texture significantly different from that of the full-fat product Different techniques have been tried to improve the body and texture of these yoghurts, most of them by replacing the milk fat by modified starch, gelatin, pectin or by using starter cultures producing exopolysaccharides. Application of High pressure homogenization (HPH) to milk for yoghurt production has been proposed as alternative to the use of additives, which can adversely affect the flavour, aroma and mouthfeel. Aim of this work was to study the effects of HPH on viscosity Water Binding Capacity (WBC) volatile profiles as well as starter stability of low-fat yoghurts produced from homogenized milk (40, 55 and 70 MPa) added of different protein concentrations (3.8 and 4.3%). during the storage at 4°C. Results were compared to data obtained from industrial youghurts having a proteion content of 5%. the 55 MPa treatment, independentely on the protein content , has resulted able to attain viscosity and WBC values not significantly different from the industrial product. Differently, the rheological indexes of yoghurt produced from milk homogenized at 70 Mpa were lower. As far as microbiological data, the straters employed maintained levels at least of 6 log cfu/g at the end of the shelf-life, independently on the protein amount and pressure level, satisfying the FIL-IDF criteria. Moreover , the chromatographic profiles of the volatile compounds, detected at the end of the shelf-life, have shown no significant differences amonf the yoghurts produced from HPH milk with reduced protein contents and industrial product. The results have permitted to select the optimal level of pressure (55MPa) to produce low fat yoghurt characterized by a lower protein content but with with rheological and microbiological features similar to the traditional products.

The aim of this work was to evaluate the biogenic amine (BA) content during the ripening of both bovine and ovine cheeses obtained using milk subjected to a homogenization treatment at 100 MPa before cheese-making. The data obtained were compared with those from cheeses produced by the same milks without any treatment or thermized. The results showed that both microbial ecology and BA concentrations of cheeses during ripening were significantly influenced by the type of milk used for cheese-making and by the treatment applied to the raw materials. In particular, the microbial counts found in Caciotta indicated that the high pressure homogenization (HPH) of milk significantly reduced the presence of the yeasts, Micrococcaceae and lactobacilli at the end of ripening. On the other hand, the HPH treatment of milk favoured the proliferation of yeasts in ovine cheese. Moreover, the ovine cheeses were characterized by a remarkably higher accumulation of BA than bovine cheeses. However, the HPH treatment of milk was able to drastically reduce the biogenic amine concentrations in both cheese typologies at the end of ripening.

Four Yarrowia lipolytica strains were tested as cheese-ripening adjuncts with milk culture in cheese production to evaluate their effects on the microbiological and biochemical features of the cheeses. The Y. lipolytica strains were able to overcome the other naturally occurring yeasts and were compatible with lactic acid bacteria (LAB). Fourier transform infrared (FTIR) profiles and analysis of free fatty acids (FFAs) released during ripening showed that the strains induced a marked lipolysis and gave rise to different FFAs accumulation over time with respect to the control. Strain-dependent protein breakdown patterns were identified and these biochemical differences resulted in different cheese organoleptic characteristics.