A new method was developed for obtaining pure beta-CN. Calcium caseina
te (3%) was reconstituted, renneted to form a gel, cooled (4 degrees C
) to allow beta-CN dissociation from the caseinate gel, and centrifuge
d. The supernatant was warmed to 30 degrees C, precipitating pure beta
-CN from solution. Large quantities of beta-CN were recovered by scali
ng-up this procedure, but these beta-CN preparations were less pure th
an the beta-CN that was prepared on a smaller scale. Chromatography (F
PLC(R)) and urea-PAGE showed beta-CN to be the main component in the p
recipitate. Chymosin, used to form the caseinate gel, did not extensiv
ely hydrolyze beta-CN under the conditions of these experiments. Calci
um concentration, cooling time, and caseinate concentration influenced
the recovery of beta-CN. Maximum recovery of beta-CN, under the exper
imental conditions used, occurred at 10 mM calcium, 48 h of cooling, a
nd 3% caseinate concentration.