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Abstract: The effect of controlled fermentation processes on the profile of volatile and other biochemical compounds of cv. Conservolea green olives processed by the Spanish method was studied. The different treatments included: (a) inoculation with a commercial starter culture of Lactobacillus pentosus, (b) inoculation with a wild strain of Lactobacillus plantarum isolated from a previous fermentation, (c) uninoculated spontaneous process (control). Microbial growth, pH, titratable acidity, reducing sugars, organic acids and volatile compounds were monitored. Starter cultures were effective in establishing an accelerated fermentation process. Both were able to reduce the survival period of Enterobacteria by 7 days, minimizing thus the likelihood of spoilage. Higher acidification of the brines and faster pH drop was observed in inoculated processes, with L. pentosus presenting better performance than the wild strain of L. plantarum. Lactic and acetic were the major organic acids detected by HPLC, the concentration of which increased in the course of fermentation. Citric and malic acids were also present in the brines but they were degraded completely within the first 2 weeks of fermentation. Ethanol, methanol, acetaldehyde, ethyl acetate, isobutyric acid were the major volatile compounds identified by GC. Their concentration varied greatly among the fermentation processes, reflecting varying degrees of microbial activity in the brines. [Copyright &y& Elsevier]

The survival of selected lactic acid bacteria (LAB) with in vitro probiotic potential was studied during storage of cv. Halkidiki green olives previously subjected to inoculated Spanish-style fermentation. After fermentation olives were packed in polyethylene pouches, covered with freshly prepared brine (9%, w/v, NaCl), acidified with 2‰ (w/v) citric acid and 1.5‰ (w/v) ascorbic acid, and stored at 4 and 20 °C for 357 days. Four packing treatments were studied, namely olives previously fermented by (i) the indigenous microbiota (control); (ii) Lactobacillus pentosus B281; (iii) Lactobacillus plantarum B282; and (iv) a co-culture of both LAB strains. Microbiological analyses were performed on the olives in parallel with physicochemical changes (pH, titratable acidity, salt content, a w and colour) at the early (day 1), middle (day 197) and final stage (day 357) of storage, as well as sensory evaluation at the end of the storage. The survival of probiotic strains was confirmed by Pulsed Field Gel Electrophoresis (PFGE). LAB decreased throughout storage reaching a final population of ca. 3.5–4.0 log CFU/g and 4.5–5.0 log CFU/g at 4 and 20 °C, respectively. The pH values ranged between 3.90 and 4.61 during storage depending on packaging condition. PFGE analysis revealed that L. pentosus B281 and L. plantarum B282 showed a high survival rate with a recovery of 100 and 96%, respectively, at 4 °C, and less than 20% for both strains at 20 °C. Finally, in the packing treatment with a co-culture of both strains, L. pentosus dominated over L. plantarum throughout storage at both temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The performance of two strains of lactic acid bacteria (LAB), namely Lactobacillus pentosus B281 and Lactobacillus plantarum B282, previously isolated from industrially fermented table olives and screened in vitro for probiotic potential, was investigated as starter cultures in Spanish style fermentation of cv. Halkidiki green olives. Fermentation was undertaken at room temperature in two different initial salt concentrations (8% and 10%, w/v, NaCl) in the brines. The strains were inoculated as single and combined cultures and the dynamics of their population on the surface of olives was monitored for a period of 114 days. The survival of inoculated strains on olives was determined using Pulsed Field Gel Electrophoresis (PFGE). Both probiotic strains successfully colonized the olive surface at populations ranged from 6.0 to 7.0 log CFU/g throughout fermentation. PFGE analysis revealed that L. pentosus B281 presented higher colonization in both salt levels at the end of fermentation (81.2% and 93.3% in 8% and 10% NaCl brines, respectively). For L. plantarum B282 a high survival rate (83.3%) was observed in 8% NaCl brines, but in 10% NaCl the strain could not colonize the surface of olives. L. pentosus B281 also dominated over L. plantarum B282 in inoculated fermentations when the two strains were used as combined culture. The biochemical profile (pH, organic acids, volatile compounds) attained during fermentation and the sensory analysis of the final product indicated a typical lactic acid fermentation process of green olives. [Copyright &y& Elsevier]

The aim of the study was to investigate the performance of Lactobacillus plantarum T571 with probiotic potential as a co-starter culture in Feta cheese production and in its long-term storage. For this reason, Feta cheese was manufactured without (control) or with the probiotic T571 strain (probiotic) and then monitored during storage at 4 and 12 °C, respectively. The products were also inoculated with Listeria monocytogenes (3-strain cocktail). The results showed that lactic acid bacteria exceeded 6 log CFU/g during storage in all trials. The probiotic samples displayed higher acidity (≈1.5% lactic acid) and lower pH (≈4.2). Coliforms and L . monocytogenes, were inactivated in shorter time in probiotic samples, in comparison with the control ones. Pulsed field gel electrophoresis verified the presence of the probiotic strain in the cheese, until the end of storage at both temperatures, whilst the survival and distribution of the pathogenic strains depended on the trial. The sensory evaluation showed that the probiotic cheeses had desirable sensory characteristics similar to the control ones, with scores of ca . 8 on a 10 cm-scale. Finally, Fourier transform infrared spectroscopy was applied for the first time during Feta cheese storage with promising results for the rapid estimation of the microbiological counts and sensory status of cheese. Results showed that Lb. plantarum T571 highlighted desirable and robust technological properties and may be used in cheese making as an adjunct culture. [ABSTRACT FROM AUTHOR]

High pressure processing (HPP) is a preservation technology alternative to heat treatment that is mild for food, but effectively inactivates the spoilage microbiota and foodborne pathogens of several foods. The purpose of the current study was to evaluate the effect of HPP on Salmonella ser. Enteritidis, indigenous microbiota and shelf-life of chicken fillets. Chicken fillets were inoculated with S . Enteritidis at three different initial inocula (3, 5, 7 log CFU/g), packed under vacuum, treated or not with HPP (500 MPa/10 min) and stored at 4 and 12 °C. Total viable counts, S . Enteritidis, pseudomonads, Brochothrix thermosphacta , lactic acid bacteria, Enterobacteriaceae and yeasts/molds populations were determined in parallel with sensory analysis of non-inoculated samples. The HPP resulted in the reduction of the pathogen population below the detection limit of the enumeration method (0.48 log CFU/g), irrespective of the inoculum. During the shelf life of the HPP samples, the pathogens population remained below or near the detection limit of the enumeration method at both temperatures, except from the high inoculum case that an increase was observed at 12 °C. At the low inoculum level, the pathogen could not be detected with the enrichment method after the first storage days (2nd day for 4 °C and 0 day for 12 °C). The survival of Salmonella strains was assessed by pulsed field gel electrophoresis and it was shown that the survival of the different strains depended on the inoculum and storage temperature. Regarding the indigenous microbiota, Br . thermosphacta was reported for the first time to be the main spoilage microorganism that survived and dominated after the HPP. From the results it was evident that, HPP may enhance the safety and increase the shelf life (6 at 4 °C and 2 days at 12 °C) of chicken meat. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess application of free or immobilized kefir culture on apple pieces and delignified cellulosic material (DCM) in simultaneous alcoholic and malolactic cider fermentations at a wide temperature range (5–45 °C). Repeated batch fermentations were continued for higher than 7 months, showing a high operational stability of the systems and were completed in less than 24 h with immobilized cells on DCM at 37 °C. Malic acid conversion up to 71.5% and ethanol productivity values up to 56.9 g/(Ld) were recorded, which could be adopted by the industrial sector. PCR-DGGE analysis of kefir culture showed no changes in microbial diversity during cell immobilization and fermentations. Analysis of major volatiles documented a significant increase of ethyl acetate content and a decrease of higher alcohols at low temperatures. HS-SPME GC/MS analysis revealed that the highest content of esters and total volatiles was observed in cider fermented by kefir culture immobilized on apple pieces at 20 °C. Principal Component Analysis showed that mainly the immobilization support rather than the temperature had a significant effect on volatile composition. Finally, the sensory evaluation ascertained the high quality of the new products. [ABSTRACT FROM AUTHOR]

Τhe aim of the present study was to evaluate the production of probiotic yoghurts using immobilized cells of Lactobacillus plantarum 2035 on whey protein along with a commercial culture. For comparison reasons, yoghurts with free L. plantarum 2035 cells and with no probiotic culture were also prepared. All products using either bovine or ewe's milk were prepared by our industrial partner (RODOPI SA dairy industry). The pH ranged between 4.1–4.4 in all cases, while the rest physicochemical characteristics ranged within usual levels. Microbiological and strain specific multiplex PCR analysis confirmed that both free and immobilized L. plantarum 2035 cells were detected in yoghurts at levels ≥6 log cfu/g after storage at 4 °C for longer period than the expiration day (≥4 weeks). Principal Component Analysis of the compounds identified by HS-SPME GC/MS analysis revealed that the milk origin affected mainly the volatile composition. Finally, the organoleptic assessment demonstrated that the new yoghurts exhibited improved sensorial characteristics compared to the commercial products. [ABSTRACT FROM AUTHOR]

Abstract: The survival of Escherichia coli O157:H7, Salmonella Enteritidis and Listeria monocytogenes during the storage of fermented green table olives cv. Halkidiki in brine was studied in parallel with the evolution of lactic acid bacteria (LAB), yeasts and pH. The olives were previously fermented with a starter culture (a potential probiotic strain of Lactobacillus pentosus B281 – starter process) or with the indigenous microbiota (control). After the end of fermentation, olives were placed in brine, inoculated with a cocktail of 5 strains of E. coli O157:H7, 5 strains of L. monocytogenes and 4 strains of S. Enteritidis, with a final concentration in the brine of ca. 7.0 log CFU/ml, and subsequently packaged in polyethylene pouches and stored at 20 °C. The population of E. coli O157:H7 reduced gradually and was detected in the brine until the 27th day of storage in both cases (i.e., starter and control process), and on olive fruits until the 19th and 16th days of storage in the starter and control process, respectively. S. Enteritidis population showed also a decrease and it was detected until the 21st day of storage in both brine and olive fruits in both cases. The population of L. monocytogenes declined during storage and it was detected until the 31st day of storage in both brine and olive fruits in both cases, showing a longer survival period in comparison to the other two studied pathogens. The presence of the potential probiotic starter did not affect the pathogen survival. The results demonstrated that even though the growth of the pathogenic strains was not supported, they may survive for a long period in a stressful environment of a fermented product with low pH value (4.2) and high salt concentration (6.0%). These results are a valuable contribution to risk assessment studies related to ready to eat foods in general. [Copyright &y& Elsevier]

Abstract: The present study aims to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from naturally fermented olives and select candidates to be used as probiotic starters for the improvement of the traditional fermentation process and the production of newly added value functional foods. Seventy one (71) lactic acid bacterial strains (17 Leuconostoc mesenteroides, 1 Ln. pseudomesenteroides, 13 Lactobacillus plantarum, 37 Lb. pentosus, 1 Lb. paraplantarum, and 2 Lb. paracasei subsp. paracasei) isolated from table olives were screened for their probiotic potential. Lb. rhamnosus GG and Lb. casei Shirota were used as reference strains. The in vitro tests included survival in simulated gastrointestinal tract conditions, antimicrobial activity (against Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli O157:H7), Caco-2 surface adhesion, resistance to 9 antibiotics and haemolytic activity. Three (3) Lb. pentosus, 4 Lb. plantarum and 2 Lb. paracasei subsp. paracasei strains demonstrated the highest final population (>8 log cfu/ml) after 3 h of exposure at low pH. The majority of the tested strains were resistant to bile salts even after 4 h of exposure, while 5 Lb. plantarum and 7 Lb. pentosus strains exhibited partial bile salt hydrolase activity. None of the strains inhibited the growth of the pathogens tested. Variable efficiency to adhere to Caco-2 cells was observed. This was the same regarding strains'' susceptibility towards different antibiotics. None of the strains exhibited β-haemolytic activity. As a whole, 4 strains of Lb. pentosus, 3 strains of Lb. plantarum and 2 strains of Lb. paracasei subsp. paracasei were found to possess desirable in vitro probiotic properties similar to or even better than the reference probiotic strains Lb. casei Shirota and Lb. rhamnosus GG. These strains are good candidates for further investigation both with in vivo studies to elucidate their potential health benefits and in olive fermentation processes to assess their technological performance as novel probiotic starters. [Copyright &y& Elsevier]

Abstract: A total of 145 lactic acid bacteria (LAB) isolates have been recovered from fermented table olives and brine and characterized at strain level with molecular tools. Pulsed-Field Gel Electrophoresis (PFGE) of ApaI macrorestriction fragments was applied for strain differentiation. Species differentiation was based either on Denaturing Gradient Gel Electrophoresis (PCR-DGGE) (black olives) or on restriction analysis of the amplified 16S rRNA gene (PCR-ARDRA) (brine and green olives). Species identification was based on sequence analysis of 16S rRNA gene. When the data were insufficient to resolve the species level of the isolates, specific multiplex PCR assays targeting the recA or tuf genes were employed. From 145 LAB isolates, 71 different strains were recovered from fermented olive and brine samples; 17 strains were assigned to Leuconostoc mesenteroides, 51 were grouped in Lactobacillus plantarum group (including 13 L. plantarum, 37 Lactobacillus pentosus, 1 Lactobacillus paraplantarum), 2 Lactobacillus paracasei subsp. paracasei and 1 Leuconostoc pseudomesenteroides. L. plantarum was recovered mainly from green olive fermentation, whereas in black olives the main species identified were L. pentosus and Ln. mesenteroides). These observations reveal that olives are a highly diverse ecosystem regarding the presence of LAB, which may affect the quality of the final fermented product. [Copyright &y& Elsevier]

The performance of the Lactobacillus plantarum L125 strain with probiotic potential, previously isolated from a traditional Greek fermented sausage, was assessed as an adjunct culture for the production of dry-fermented pork sausages. The probiotic was added in the meat batter with the commercial starter cultures and the microbial populations were estimated during fermentation, ripening and storage at 4 and 12 °C, respectively. Physicochemical analyses (pH and a w), sensory evaluation and Fourier Transform Infrared Spectroscopy (FTIR) were also performed, while the presence of L125 strain was monitored by Pulsed Field Gel Electrophoresis. Lactic acid bacteria (LAB) counts at the inoculation time were 8.21 and 6. 44 log CFU/g for the probiotic and control samples, respectively, while the L125 strain maintained high population levels (> 6 log CFU/g) during storage. At the end of the ripening, the products exhibited similar pH values of 4.46 and 4.42 and a w values of 0.87 and 0.85 for the control and probiotic case, respectively. FTIR spectroscopy application in combination with data analytics, resulted in the acceptable estimation of LAB population, but further studies are needed to improve the technique's performance. Overall, the Lb. plantarum L125 was found to possess desirable technological characteristics, indicating its effectiveness to be used in fermented sausage manufacturing. • Lb. plantarum L125 was assessed as adjunct probiotic culture in fermented sausages. • Microbiological, physicochemical, sensory, molecular and FTIR analyses were performed. • L125 was detected in high levels (> 6 log CFU/g) during storage. • The new product showed sensorial properties similar to or better than the control. • The microbial and sensory status of product were estimated through the FTIR-PLS models. [ABSTRACT FROM AUTHOR]