Effect of Adding Lactoferrin on Some Foodborne Pathogens in Yogurt

Lactoferrin is a natural biological active cationic protein that can be used as a yogurt additive to inhibit the growth of foodborne pathogens. The present study evaluated the antimicrobial effects of lactoferrin against Bacillus cereus, Enterococcus faecalis, and Candida albicans inoculated in laboratory prepared yogurt at refrigerator temperature. The pre-warmed skimmed milk was inoculated by commercial starter and then divided into 3 parts, each inoculated by different inoculum and a certain concentration of lactoferrin (0.5% and 1.5%) and incubated at 42oC for 4 h till curd formation. Tenfold serial dilutions were performed for each group and refrigerated at4±1oC  for up to 14 days to be examined every day. The obtained results showed that the treated yogurt samples with lactoferrin had significant reductions in B. cereus, Ent. faecalis, and C. albicans counts than untreated samples (control positive). Generally, yogurt samples treated with 1.5% lactoferrin showed the highest reduction percentages on B. cereus and C. albicans than 0.5% lactoferrin. In addition, B. cereus showed more susceptibility to lactoferrin than Ent. faecalis; the maximum reduction of the inoculated B. cereus was observed on the sixth day of the incubation to be 99.99%. Maximum reduction of the tested C. albicans was observed after the seventh day.  The application of lactoferrin showed a potentially significant antimicrobial effect against B. cereus, Ent. faecalis, and C. albicans in refrigerating conditions, so lactoferrin is recommended to be used in yogurt production for safe product manufacturing.