Abstract Lactic acid bacteria have been studied for their ability to accumulate inorganic selenium, which is reduced to its elemental form or could be integrated into selenoproteins in the form of selenocysteine. This ability to produce bioavailable organic selenium for humans is an advantage that could be exploited in the production of functional foods. In this work, Enterococcus faecium ABMC-05 isolated from a traditional Mexican beverage (tepache) and with NCBI entry number OL413240 was used. Microorganism selenization was performed after the determination of minimal inhibitory concentration of Na2SeO3 (184 mg/L), which was calculated using the graphical method of Talmadge and Fitch. The selenium concentration of accumulated selenium was calculated by inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration of selenium at 48 h of fermentation was 39.92 mg/L, which represented 23.8% of selenium at medium. This value was consistent with those reported for other lactic acid bacteria. Finally, it was determined the selenocysteine presence in biomass recovery after fermentation using RP-HPLC technique. With these results it was confirmed the biogenic production of selenocysteine by Enterococcus faecium ABMC-05 using an inorganic source.

Abstract The importance of functional foods added with probiotics and prebiotics is directly related with the promotion of the health benefits of human. In this study the survival of the probiotic Lactobacillus rhamnosus GG in a semi-ripened cheese added with agave juice, was determined. Cheese ripening was carried out at 14 °C for 35 days. The pH changes were measured and the hydrolysis of the protein was evaluated through the analysis of free amino groups by the trinitrobenzenesulfonic acid (TNBS) method and SDS-PAGE polyacrylamide gel electrophoresis. At the end of the study, in the symbiotic cheese, the viability of the probotic was increased in two logarithmic cycles (from 6.73 to 8.72 log CFU). A more active proteolytic process was observed with the addition of agave juice, due to the high production of low molecular weight peptides and the concentration of free amino groups (8.63 mg/L). The pH did not have a significant difference between the control and the cheese studied. With the obtained results, it is seen that agave juice is an ingredient that can be added to semi ripening cheeses with the objective of improving the survival capacity of probiotic microorganisms, which are used as starters.

Abstract This research aimed to understand how the storage conditions change the appearance of an apple compote added with white wine (ACWW) during storage at different temperatures (20, 30, and 40 °C) for 63 days. Microbiological quality, color parameters, and pH were monitored. The CIE L*, a*, and b* color variables were measured through image analysis. The parameters associated with the color changes during storage were the most critical quality indices of the ACWW, especially the overall color difference (ΔE), since it presented the larger velocity constants, fitting to the first-order reaction kinetic model. Therefore, ΔE was selected as a critical parameter to estimate shelf-life but fitted with the first-order fractional conversion model, which provided a shelf-life of 45.64 days at 20 °C. The shelf-life decreased with increasing storage temperature. In conclusion, the results demonstrated the applicability of the image analysis and the kinetics-based accelerated shelf-life testing approach to obtain faster insight into quality attributes changes, mainly color changes in compotes and similar products.

Abstract In food systems, lipid oxidation is one of the most important factors affecting food quality, nutrition, safety, color and consumer acceptance. The objective of this study was to determine the kinetic parameters of lipid oxidation and its influence in the shelf life of third generation (3G) snacks stored in three types of packaging (polyethylene, polypropylene + Kraft paper, and polyethylene + polypropylene) at 25 °C and 40 °C. The peroxide value was the quality parameter selected and monitored for a 60 day period using a spectrophotometric technique. Based on the Arrhenius equation and activated complex theory, reaction rate constants (k), activation energies (Ea), Q10 factors, activation enthalpies (∆H‡), and activation entropies (∆S‡ ) for oxidative stability in 3G snacks were calculated. Results showed that oxidation phenomena can occur in the 3G snacks and affect its shelf-life. Packaging C (polyethylene + polypropylene) was the most appropriate for the storage of this kind of product. Finally, the shelf life of the analyzed pellets was longer than one year at 25 °C and it may be extended with the appropriate mix of packaging materials.

Abstract In this study, the survival and proteolysis of lactic acid bacteria Lactobacillus casei Shirota and Lactobacillus rhamnosus GG were measured in fermented milks enriched with agave juice and inulin. Fermentations were terminated at pH 4.5 and stored for 21 days at 4 °C. Survival was determined by viable count in MRS-agar. The production of free amino groups was performed by the TNBS method and peptide separation was performed by SDS-PAGE. During fermentation, pH decreased faster in milk with agave juice than with inulin. There was no significant difference in the concentration of free amino groups (0.632 ± 0.007 and 0.627 ± 0.007 mg/L) between the two fermentation systems for any microorganism. The concentration of lactic acid bacteria in the presence of agave juice was higher than the recommended concentration for probiotic foods (7.59 log CFU/mL for L. rhamnosus GG and 8.26 log CFU/mL for L. casei Shirota). The production of free amino groups and peptides of low molecular weight continued in refrigeration and was higher in systems with agave juice. This could represent a proteolytic activation in the presence of this carbon source. The results showed that agave juice might be a functional ingredient with prebiotic character in symbiotic systems.

ABSTRACT In the last decade, thrombosis has been one of the pathologies with high incidence creating great concern in Health Institutes all around the world. Considering this, the aim of this research was to determine the antithrombotic activity of peptides released during lactic fermentation. Reconstituted skim milk powder was fermented by Lactobacillus casei Shirota and Lactobacillus johnsonii LA1 isolated from commercial fermented milks. The hydrolysis degree and proteolytic profile were analyzed by trinitrobenzenesulfonic acid spectrophotometry method and by peptide polyacrylamide electrophoresis gel separation. The milk fermented by Lactobacillus casei Shirota exhibited a higher concentration of free amino groups than that fermented by Lactobacillus johnsonii LA1. Additionally, in both fermentation systems peptides with molecular weights lower than 1.4 kDa were observed. The highest inhibition of thrombin (31.67±2.35%) was observed in milk fermented by Lactobacillus johnsonii LA1 at 10 hours of fermentation. Finally, no relationship was found between the antithrombotic capacity and the proteolytic profile.

Milk is an important source of bioactive compounds. Many of these compounds are released during fermentation and refrigerated storage. The aim of this study was to determine the release of peptides by lactic acid bacteria in commercial fermented milk during refrigerated storage. The size and profile of peptides were analyzed by polyacrylamide gel electrophoresis and sizeexclusion HPLC. During electrophoresis, it was observed that the peptides were released from caseins, whereas β-lactoglobulin was the whey protein with the highest degradation. HPLC analysis confirmed the pattern of peptide formation observed in electrophoresis. Two fractions lower than 2 kDa with aromatic amino acids in their structure were separated. These results were consistent with those reported for structures of peptides with antihypertensive activity. Therefore, the presence of aromatic amino acids in the peptide fractions obtained increases the likelihood of finding peptides with such activity in refrigerated commercial fermented milk. In conclusion, during cold storage, peptides with different molecular weights are released and accumulated. This could be due to the action of proteinases and peptidases of the proteolytic system in lactic acid bacteria.