Use of Hydrolyzed Whey Peptide to Inhibit Culture Agglutination

¹ Department of Animal Sciences, University of Kentucky, Lexington 40546
² Food Science and Technology, The Federal Polytechnic, Bauchi, PMB 0231 Bauchi State, Nigeria

Papain was used to hydrolyze sweet whey to prepare peptides that were harvested with ultrafiltration membranes (molecular weight cutoffs of 10,000, 3000, and 1000). Insure® buffer salts were added to whey peptides (ratio 40:60% solids, respectively) to prepare media that were tested for their ability to inhibit culture agglutination. Commercial Insure® medium (75.7 g/l) was used as a control. Skim milk (240 ml) in 250-ml graduated cylinders was inoculated (4%) with Lactococcus lactis spp. lactis B62 or E72. Culture agglutination was determined by measuring upper center and bottom pH values of the skim milk column during 5 h of incubation. A pH differential was calculated by subtracting the bottom pH from the upper center pH. Cultures grown in media containing whey peptides agglutinated in skim milk to a lesser degree than when grown in the control medium. Culture agglutination was inhibited to a greater degree when cultures were grown in the 1000 molecular weight cutoff peptide medium than when grown in the 10,000 or 3000 molecular weight cutoff peptide medium. When culture E72 was grown in medium containing 1000 molecular weight cutoff peptides, culture agglutination was completely inhibited.

Key Words: whey peptides • Lactococcus • culture agglutination • papain

Submitted on June 21, 1999
Accepted on January 31, 2000