Ah. Pripp et al., Quantitative contribution of rennet and bacterial proteolytic enzymes to the primary proteolysis in sodium caseinate solution, MILCHWISSEN, 55(5), 2000, pp. 263-266
In this study the contribution of different proteolytic agents to primary p
roteolysis in a sodium caseinate solution under cheese-like conditions was
quantified, The sodium caseinate solutions were treated with rennet, sonica
ted cell suspension of Lactococcus lactis subsp, cremoris SK11 and heat ina
ctivated sonicated cell suspension. Proteolysis was assessed after 3, 10 an
d 17 days incubation at 8 degrees C by urea-PAGE gels of the pH 4.6-insolub
le fraction. Principal component analysis of the gels estimated rennet and
incubation time to contribute to > 90% and -3%, respectively, of the total
variation in primary proteolysis between the assessed samples. Sonicated ce
ll suspension was estimated to contribute to similar to 8% of the total var
iation in primary proteolysis between samples incubated for 17 days. Bacter
ial proteolytic enzymes showed an interactive effect with rennet by degradi
ng beta-I-CN (beta-CN f1-192) in the rennet-treated samples. A heat-inactiv
ated sonicated cell suspension had no detectable influence on proteolysis.