Use of nisin and bioprotective lactic cultures to extend the shelf life of sheep and goat cheese whey

We evaluated the feasibility of using nisin (12.5 mg/L) and the inoculation of Lactobacillus helveticus (LH 091-C28527), Lacticaseibacillus rhamnosus (LRB-0283705A) and Lacticaseibacillus casei (BGP1-304799A) commercial cultures as bioprotectors in sheep (SCW) and goat (GCW) cheese whey. The results showed that nisin inhibited L. helveticus and the native population and reduced L. rhamnosus counts (similar to 4.5 log CFU/mL). L. casei grew during storage in the presence/absence of nisin, reaching counts for probiotic appeal, whereas L. rhamnosus was partially inactivated. L. helveticus fermented SCW in 23-46h and GCW in 60h and was inhibited by L. rhamnosus. Moreover, fermented samples had lower counts of lactic acid bacteria after storage (<= 3.6 log CFU/mL), showing inhibition by pH. Thus, among the studied alternatives, the addition of nisin and/or L. casei is the best option to prolong the shelf life of SCW and GCW by up to 28 days. These results are useful for artisanal production and can be directly applied for whey preservation.