Proteolytic enzyme activities in Cheddar cheese juice made using lactococcal starters of differing autolytic properties.
OBJECTIVE
To determine proteolytic enzyme activities released in Cheddar cheese juice manufactured using lactococcal starter strains of differing autolytic properties.


RESULTS
The activities of residual chymosin, cell envelope proteinase and a range of intracellular proteolytic enzymes were determined during the first 70 days of ripening when starter lactococci predominate the microbial flora. In general, in cell free extracts (CFE) of the strains, the majority of proteolytic activities was highest for Lactococcus lactis HP, intermediate for L. lactis AM2 and lowest for L. lactis 303. However, in cheese juice, as ripening progressed, released proteolytic activities were highest for the highly autolytic strain L. lactis AM2, intermediate for L. lactis 303 and lowest for L. lactis HP.


CONCLUSIONS
These results indicate that strain related differences in autolysis influence proteolytic enzyme activities released into Cheddar cheese during ripening. No correlation was found between proteolytic potential of the starter strains measured in CFE prior to cheese manufacture and levels of activities released in cheese juice.


CONCLUSIONS
The findings further support the importance of autolysis of lactococcal starters in determining the levels of proteolytic activities present in cheese during initial stages of ripening.
Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, Co Cork, Ireland.
A
A
Sheehan
G O'
GO
Cuinn
R J
RJ
Fitzgerald
M G
MG
Wilkinson
D002611:Cheese / Q000382:microbiology*; D012085:Chymosin / Q000378:metabolism; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D013294:Lactococcus lactis / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism*
D007770:L-Lactate Dehydrogenase; D010447:Peptide Hydrolases; D012085:Chymosin