Selenium nanoparticles (SeNPs) are gaining importance in the food and medical fields due to their antibacterial properties. The microbial inhibition of these kinds of particles has been tested in a wide range of Gram (+) and Gram (−) pathogenic bacteria. When SeNPs are synthesized by biological methods, they are called biogenic SeNPs, which have a negative charge caused by their interaction between surface and capping layer (bioorganic material), producing their high stability. This review is focused on SeNPs synthesis by bacteria and summarizes the main factors that influence their main characteristics: shape, size and surface charge, considering the bacteria growth conditions for their synthesis. The different mechanisms of antimicrobial activity are revised, and this review describes several biosynthesis hypotheses that have been proposed due to the fact that the biological mechanism of SeNP synthesis is not fully known.

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Extracts of wheat bran and barley husk with solvents of different polarity were analyzed to determine the concentration of bioactive compounds (phytic acid, saponins, flavonoids, total phenolic compounds and phenolic profile) and their antioxidant activity by DPPH and ABTS assays. The results showed that the phytic acid concentration in wheat bran was higher than the phytic acid concentration in barley husk. The concentration of saponins was inverse with higher concentrations in barley husk than wheat bran. The solvents with the highest extraction of phytochemicals were 80% ethanol in wheat bran and 50% acetone in barley husk. The chromatograph profile showed that wheat bran presented a greater concentration of caffeic acid and barley husk contained kampferol. The properties of extraction solvents significantly affected the concentration of flavonoids, phenolic compounds, and antioxidant activity. The addition of water to the solvents increased the extraction efficiency of bioactive compounds and antioxidant activity. The results for barley husk are among the first reported because there are few studies on this cereal.

Gut microbiota is a group of microorganisms that are deposited throughout the entire gastrointestinal tract. Currently, thanks to genomic tools, studies of gut microbiota have pointed towards the understanding of the metabolism of important bacteria that are not cultivable and their relationship with human homeostasis. Alterations in the composition of gut microbiota could explain, at least in part, some epidemics, such as diabetes and obesity. Likewise, dysbiosis has been associated with gastrointestinal disorders, neurodegenerative diseases, and even cancer. That is why several studies have recently been focused on the direct relationship that these types of conditions have with the specific composition of gut microbiota, as in the case of the microbiota–intestine–brain axis. In the same way, the control of microbiota is related to the diet. Therefore, this review highlights the importance of gut microbiota, from its composition to its relationship with the human health–disease condition, as well as emphasizes the effect of probiotic and prebiotic consumption on the balance of its composition.

Amaranthus hypochondriacus spp. is a commonly grown cereal in Latin America, known for its high protein content. The objective of this study was to separate and identify bioactive peptides found in amaranth seeds through enzymatically-assisted hydrolysis using alcalase and flavourzyme. Hydrolysis was carried out for each enzyme separately and compared to two-step continuous process where both enzymes were combined. The biological activity of the resulting three hydrolysates was analyzed, finding, in general, higher bioactive potential of the hydrolysate obtained in a continuous process (combined enzymes). Its fractions were separated by RP-HPLC, and their bioactivity was analyzed. In particular, two fractions showed the highest biological activity as ACE inhibitors with IC50 at 0.158 and 0.134, thrombin inhibitors with IC50 of 167 and 155, and antioxidants in ABTS assay with SC50 at 1.375 and 0.992 mg/L, respectively. Further sequence analysis of the bioactive peptides was carried out using MALDI-TOF, which identified amino acid chains that have not been reported as bioactive so far. Bibliographic survey allowed identification of similarities between peptides reported in amaranth and other proteins. In conclusion, amaranth proteins are a potential source of peptides with multifunctional activity.

Presence of antibiotic‐resistant Salmonella strains on raw carrots was evaluated, as was the antibacterial activity of roselle calyx extracts against any identified resistant Salmonella strains. One hundred samples of carrots were collected from markets in Pachuca, Mexico. Salmonella was isolated from the carrot samples by culture procedure. Susceptibilities to sixteen antibiotics were determined for the isolated Salmonella strains by standard test. Antibacterial activity versus the isolated strains was measured for roselle extracts produced with water, methanol, acetone and ethyl acetate. Finally, the antibacterial effect of roselle extracts, sodium hypochlorite, acetic acid and colloidal silver against Salmonella strains isolated from carrots was evaluated on contaminated carrots. Thirteen Salmonella strains were isolated from 11% of the carrot samples. All strains exhibited resistance to at least two of the tested antibiotics. Roselle extracts caused a greater reduction in concentration of Salmonella than the sodium hypochlorite, acetic acid and colloidal silver on contaminated carrots. Practical Applications Roselle Hibiscus sabdariffa calyx extracts exhibited antimicrobial activity on culture media and on carrots against multidrug‐resistant Salmonella strains. The information presented shows that water extract of roselle calyx may be a potentially useful addition to disinfection procedures of raw carrots in field, carrot processor plants, restaurants and home.

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.