Isolation and purification of bioactive peptides from yogurt whey: Application as a natural preservative in a model food system

The aim of this study was to isolate and purify bioactive peptides from yogurt whey and use these peptides in a food model system. Yogurt whey protein was hydrolyzed by pepsin and trypsin, then the hydrolysates were passed through ultrafiltration membranes and the filtrate with the highest antimicrobial and anti‐oxidant activity was fractionated using RP‐HPLC. The hydrolysate fraction with the highest anti‐oxidant and antibacterial activity was obtained from trypsin with a molecular weight of 5–10 kDa. The peptide fractions of this hydrolysate were isolated using RP‐HPLC, and it was shown that the second fraction had the highest antioxidant and antimicrobial activity. SDS‐PAGE analysis relieved that the molecular weight of this fraction was 5 kDa. This peptide which was added to Iranian fermented dairy drink showed a good antibacterial effect and had no negative effect on overall acceptability. Therefore, this peptide can be used as a natural preservative in food products. Practical applications In this study, bioactive peptides were isolated and purified from yogurt whey. Low molecular weight (5 kDa) bioactive peptide prepared with trypsin had the highest antioxidant and antimicrobial activity. Therefore, it is recommended to use these peptides as therapeutic peptides to prevent and treat oxidative stress‐related diseases. This bioactive peptide can also be used as a natural alternative to synthetic preservatives in food industries.