Milk is a source of proteins with high nutritional value and relevant biological activities. Bioactive milk proteins, like lactoferrin, are important for newborn development and can also be used as ingredients in functional products to improve health. Lactoferrin is essential in infant’s diet, since protects against infections and promotes immune system maturation. Bovine lactoferrin is used to supplement formula milk in order to strengthen baby’s defences against some pathogenic bacteria. Thus, lactoferrin supplemented formula can be a barrier against emergent pathogens, such as Cronobacter sakazakii, which has caused great concern in the last few years. Milk proteins generate bioactive peptides in the digestion process, and it is known that industrial processing can modify their susceptibility to digestion. Treatments such as heating have been shown to denature whey proteins and make them more easily digestible. Therefore, the aim of this study was to analyze the effect of technological treatments and gastrointestinal digestion on the antibacterial activity against C. sakazakii of proteins present in dairy formulas supplemented with lactoferrin. Commercial bovine lactoferrin has been shown to have antibacterial activity against C. sakazakii, both in the native state and after static in vitro gastrointestinal digestion. In addition, the digests obtained from dairy formulas subjected to technological treatments, either homogenization or pasteurization, have higher antibacterial activity than non-treated formulas. The release of low molecular weight peptides during the in vitro gastric digestion is probably the cause that would explain the enhanced antibacterial activity of the digested dairy formulas.

The dairy industry generates a large volume of by-products containing bioactive compounds that may have added value. The aim of this study was to evaluate the antioxidant and antigenotoxic effects of milk-derived products, such as whey, buttermilk, and lactoferrin, in two human cell lines: Caco-2 as an intestinal barrier model and HepG2 as a hepatic cell line. First, the protective effect of dairy samples against the oxidative stress caused by menadione was analyzed. All these dairy fractions significantly reversed the oxidative stress, with the non-washed buttermilk fraction presenting the greatest antioxidant effect for Caco-2 cells and lactoferrin as the best antioxidant for HepG2 cells. At concentrations that did not impact cell viability, we found that the dairy sample with the highest antigenotoxic power against menadione, in both cell lines, was lactoferrin at the lowest concentration. Additionally, dairy by-products maintained their activity in a coculture of Caco-2 and HepG2, mimicking the intestinal-liver axis. This result suggests that the compounds responsible for the antioxidant activity could cross the Caco-2 barrier and reach HepG2 cells on the basal side, exerting their function on them. In conclusion, our results show that dairy by-products have antioxidant and antigenotoxic activities, which would allow revaluing their use in food specialties.