This study aimed to evaluate the antimicrobial activity of both cells, and cell-free supernatants (CFS) of 7 selected lactic acid bacteria (LAB) strains belonging to Limosilactobacillus fermentum (4 strains), Lacticaseibacillus paracasei (1 strain), Lacticaseibacillus rhamnosus (1 strain), and Enterococcus faecium (1 strain) species, against Listeria monocytogenes, Escherichia coli, Salmonella Typhimurium, Pseudomonas aeruginosa and Staphylococcus aureus, by both the agar-well diffusion and co-culture methods. In addition, probiotic and safety traits were also detected. Great variability was detected on antimicrobial effects, whereas all tested strains were found sensitive to most of the tested antibiotics, and without any DNase, gelatinase, or hemolytic activity. Moreover, strains showed excellent survival in acidic conditions and exhibited tolerance to pepsin and bile salts. Based on the in vitro results, the CFSs of two selected L. fermentum strains were applied, in a mixed solution, as bio-preservative into minimally processed pomegranate arils, inoculated with a cocktail of L. monocytogenes and E. coli. Samples, packaged in an ordinary atmosphere, were analyzed during refrigerated storage, for up to 12 days, for physicochemical (as weight loss, texture, color, pH, total soluble solids and organic acid content) and for microbiological traits. Results revealed the effectiveness of CFS, up to 12 days, in reducing weight loss and microbial growth, without any significant effect on texture, total soluble solid content and color, found comparable to the acid citric treatment, highlighting the multi-functional potential of selected probiotic strains.

Recently, a new type of cow’s milk has been commercialized in the markets, called A2 milk. It is derived from a specific allelic composition on chromosome 6. The only difference between A1 and A2 milk results from the polymorphism at the 67 amino acid chain. In this position, A2 milk has a proline amino acid, while A1 milk has a histidine amino acid. Proteins are one of the most important components of milk, especially casein, and have received significant attention as they are the source of bioactive opioid peptides called beta-casomorphin-7. Peptides are released through enzymatic digestion of casein and whey proteins. More precisely, this bioactive peptide is produced by sequential gastrointestinal digestion of bovine A1 variants proteins, while this phenomenon is not present in variant A2. Studies have reported that A1 milk can be harmful to health not only for adults but also for infants and that β-casein A2 becomes a safer choice following the relationship between disease risk and consumption of the beta-casomorphin-7 peptide. Indeed, epidemiological studies suggest that the released beta-casomorphin-7 peptide is a risk factor for the development of diseases in humans, but this has not yet been validated by other studies. In contrast, A2 milk has been suggested as an appropriate substitute for A1 milk since populations consuming milk containing high levels of the A2 beta-casein variant have lower rates of diseases, such as diabetes, coronary heart disease, autism, and schizophrenia.

The aim of this study was to investigate the relationship between the β-casein CSN2 genotypes (A1A1, A1A2, A2A2) and the biochemical characters and fatty acid composition of milk. Twenty-three milk samples from Jersey cows from the same herd from a farm in Hungary were studied. Animals were grouped according to β-casein genotype variants A1A1, A1A2 and A2A2. A1A1 milk had a significantly higher content of monounsaturated fatty acids (P