Md. Larsen et al., CHARACTERIZATION OF THE PROTEOLYTIC ACTIVITY OF STARTER CULTURES OF PENICILLIUM-ROQUEFORTI FOR PRODUCTION OF BLUE VEINED CHEESES, International journal of food microbiology, 43(3), 1998, pp. 215-221
Thirty strains of Penicillium roqueforti used for the production of bl
ue cheeses were examined for proteolytic activity by agar diffusion on
casein agar, by the azocasein test and by capillary zone electrophore
sis (CE). Distinct differences were seen between the strains by all th
ree methods applied and the 30 strains could be subdivided in three gr
oups being significantly different in their proteolytic activity as me
asured by the agar diffusion test. The quantitative differences seen i
n the agar diffusion test were confirmed by the azocasein test. Howeve
r, a negative result on casein agar, i.e., no clearing of the agar was
observed for one strain while it showed low proteolytic activity in t
he azocasein test. CE proved to be a valuable method for revealing qua
litative differences between strains of P. roqueforti in the breakdown
of casein. Three strongly proteolytic strains broke down the specific
casein fractions differently: one strain broke down beta A1-casein fa
ster than beta A2-casein, the second preferred alpha(s1)-casein while
the last strain broke down the casein fractions at equal rates. For a
strain with medium proteolytic activity, the degradation of casein was
seen by the appearance of a peak with migration time similar to alpha
(s1)-I casein, a peptide normally produced by chymosin. (C) 1998 Elsev
ier Science BN. All rights reserved.