Use of an Enzyme-Treated, Whey-Based Medium to Reduce Culture Agglutination

¹ Michigan State University, Department of Food Science and Human Nutrition, East Lansing 48824
² University of Kentucky, Department of Animal Sciences, Lexington 40546

Rennet whey was hydrolyzed with papain during diafiltration at 40°C over a 2-h period. Permeate collected from a membrane with a molecular weight cut-off of 10,000 was freeze-dried and added to internal pH-controlled buffer salts as a replacement of the whey fraction. A control medium was prepared using dried whey. Both media were reconstituted (7.5% solids) and heat treated (85°C for 45 min). Commercial lactic cultures OS, M30, and M37 were grown in both media to prepare bulk starter. Pasteurized skim milk (1000 ml) in graduated cylinders was inoculated (5%) with bulk starter, Top and bottom pH of the skim milk was determined at 1-h intervals for 5 h. Culture agglutination was inhibited by 55 and 72% for cultures M30 and M37, respectively, when cultures were grown in the hydrolyzed whey media. Microscopic examination showed that cultures grown in hydrolyzed whey media formed considerably shorter chains and had little to no clumping.

Key Words: agglutination • cultures • media • enzyme

Submitted on September 13, 1994
Accepted on February 11, 1994