Beta-casein makes up about 30% of the total protein contained in milk and can be present in cows' milk in two distinct forms (A1 or A2) or as a combination of the two. The only difference between these two variants of β-casein (β-CN) is a single amino acid substitution. This results in a different behavior of the protein upon enzymatic cleavage, following human consumption or due to microbial action. In most of the commercially available milk containing A1 or A1/A2 β-CN variants, the β-casomorphin-7 peptide (BCM-7) is released upon digestion and during cheese manufacturing/ripening, while this does not happen with A2 milk. BCM-7 is a known μ-opioid receptor agonist that may influence the gastro-intestinal physiology directly and may also exert effects elsewhere in the body, such as on the cardiovascular, neurological and endocrine systems. The present article is aimed at a revision of prior review papers on the topic, with a focus on the impact of ingestion of A1 β-CN milk and A2 β-CN milk on any health-related outcomes and on the impact of A1 or A2 β-CN variant on technological properties of cows' milk. When systematic reviews were considered, it was possible to conclude that A2 β-CN exerts beneficial effects at the gastrointestinal level compared with A1 β-CN, but that there is no evidence of A1 β-CN having negative effects on human health. Physicochemical differences among cows' milk containing either β-CN A2 or β-CN A1 and their effects on technological properties are discussed.

Lactic acid bacteria (LAB) potential in the food industry and in the biotechnological sector is a well-established interest. LAB potential in counteracting especially food-borne infections has received growing attention, but despite being a road full of promises is yet poorly explored. Furthermore, the ability of LAB to produce antimicrobial compounds, both by ribosomal synthesis and by decrypting them from proteins, is of high value when considering the growing impact of multidrug resistant strains. The antimicrobial potential of 14 food-derived lactic acid bacteria strains has been investigated in this study. Among them, four strains were able to counteract Listeria monocytogenes growth: Lactococcus lactis SN12 and L. lactis SN17 by high lactic acid production, whereas L. lactis 41FLL3 and Lactobacillus sakei I151 by Nisin Z and Sakacin P production, respectively. Strains Lactococcus lactis MG1363, Lactobacillus rhamnosus 17D10 and Lactobacillus helveticus 4D5 were tested and selected for their potential attitude to hydrolyze caseins. All the strains were able to release bioactive peptides with already known antimicrobial, antihypertensive and opioid activities. These features render these strains or their bioactive molecules suitable for use in food as biocontrol agents, or as nutraceutical supplements to treat mild disorders such as moderate hypertension and children insomnia. These results highlight once again that LAB potential in ensuring food safety, food nutraceutical value and ultimately in favoring human health is still underexplored and underexploited.

Background: Silkworm pupae is the main by-product of the sericulture industry with an interesting nutritional profile, especially in terms of proteins. In consideration of its possible use as a food or food ingredient in Western countries, a comparative proteomic experiment has been performed to investigate the differences of the protein profile of male and female silkworm pupae reared on mulberry leaves or on an artificial diet. Methods: The nutritional profile of lyophilized silkworm pupae in terms of dry matter and ash was evaluated according to the AOAC procedures, the total nitrogen content was determined by a nitrogen analyzer and the silkworm pupae gross energy value was measured using an adiabatic calorimetric bomb. The comparative proteomic analysis was performed on male and female silkworm pupae reared on mulberry leaves or on the artificial diet. Proteins were separated by two-dimensional electrophoresis and, after a multivariate statistical analysis, the differentially expressed proteins were identified by LC-MS/MS. Results: The comparative proteomic approach highlighted 47 silkworm pupae proteins differentially expressed comparing diet and gender. PCA analysis showed that seven proteins were more effective in discriminating the sex and five were more effective in discriminating the diet type. In spite of the above-mentioned differences in the silkworm pupae protein profile, no strong alteration of the pupa physiological traits have been demonstrated, suggesting a general silkworm pupae flexibility to adapt to a well-balanced artificial diet. Differences in lipid transport and metabolism were found among the experimental groups, that might have a relevant effect on the timing and on hormone secretion. This aspect may also affect silk production, as univoltine strains are the most productive. The proteomic data provided in this work, may offer a contribution in understanding also the influence of gender and farming strategy on the allergen profile of Bombyx mori, when used as food or as a food ingredient. Female silkworm pupae reared on mulberry leaves seemed to contain lower levels of known allergens than those reared in the other experimental conditions; these findings will have to be taken into account when farming B. mori for food production purposes. However, our results need to be supported by further characterization of the allergenic potential of B. mori.