A Method for Isolating ß-Casein

¹ Department of Nutrition and Food Science, University of Minnesota, St. Paul 55108

A new method was developed for obtaining pure ß-CN. Calcium caseinate (3%) was reconstituted, renneted to form a gel, cooled (4°C) to allow ß-CN dissociation from the caseinate gel, and centrifuged. The supernatant was warmed to 30°C, precipitating pure ß-CN from solution. Large quantities of ß-CN were recovered by scaling-up this procedure, but these ß-CN preparations were less pure than the ß-CN that was prepared on a smaller scale. Chromatography (FPLC®) and urea-PAGE showed ß-CN to be the main component in the precipitate. Chymosin, used to form the caseinate gel, did not extensively hydrolyze ß-CN under the conditions of these experiments. Calcium concentration, cooling time, and caseinate concentration influenced the recovery of ß-CN. Maximum recovery of ß-CN, under the experimental conditions used, occurred at 10 mM calcium, 48 h of cooling, and 3% caseinate concentration.

Key Words: ßbeta;-casein • casein • isolation

Submitted on August 10, 1995
Accepted on March 14, 1996