Gastrointestinal digestion and technological treatments modify the antibacterial activity of lactoferrin supplemented dairy matrices against Staphylococcus aureus

Milk contains antimicrobial proteins, such as lactoferrin from whey or proteins from the milk fat globule membrane (MFGM), which can be used in functional foods to strengthen children and adult defenses. Foodborne bacteria, such as Staphylococcus aureus, can contaminate dairy products causing intoxication. The aim of this study was to evaluate the antibacterial activity of lactoferrin, free and in dairy matrices, against S. aureus before and after gastrointestinal digestion. Six dairy formulas, supplemented with lactoferrin and MFGM, were subjected to technological treatments and their antibacterial effect was analyzed after in vitro digestion. Intact lactoferrin slightly reduced S. aureus growth, but its digests lost this activity. Gastric digests of non-treated or homogenized formulas reduced significantly the bacterial growth, probably due to the antimicrobial peptides generated by pepsin, while pasteurization decreased such activity. Intestinal digests showed the greatest antibacterial effect, probably due to the action of intestinal enzymes and the generated peptides.