Iv. Zarmpoutis et al., PROTEOLYSIS IN BLUE-VEINED CHEESE - AN INTERVARIETAL STUDY, Irish journal of agricultural and food research, 36(2), 1997, pp. 219-229
The extent of proteolysis in two sets of Stilton (England), Gorgonzola
(Italy), Danablu (Denmark) and Irish farmhouse varieties (Cashel and
Chetwynd) was studied. High levels of pH 4.6-soluble N and similar ami
no acid profiles were found for all cheeses but the concentration of m
ost amino acids was substantially higher in Gorgonzola than in the oth
er varieties. Glutamic acid, leucine, lysine and valine were the princ
ipal amino acids and represented about 45% of the total. Urea-polyacry
lamide gel electrophoresis showed extensive degradation of both alpha(
sl)- and beta-caseins. Reverse-phase HPLC profiles of the pH 4.6-solub
le extracts from Stilton and Danablu were similar, but the profile for
Gorgonzola was quite different and contained considerably higher conc
entrations of small peptides and free amino acids. The concentrations
of peptides with intermediate elution times were substantially higher
in Cashel blue than in the other cheeses. The profile of Chetwynd was
qualitatively similar to that of Stilton and Danablu, but showed quant
itative differences; corresponding peaks were smaller in Chetwynd. The
sub-fraction soluble in ethanol (70 ml / 100 ml) contained almost all
peptides detected in the pH 4.6-soluble fraction. The reverse-phase H
PLC chromatograms of the ethanol-insoluble fractions were quite differ
ent from those of the ethanol-soluble fractions; the chromatograms of
all cheeses contained large peaks eluting between 28 and 40 min.