Action of the lactococcal proteinase during Camembert-type curd making

Abstract

We emphasise the role of the lactococcal cell envelope proteinase (lactocepin) on the proteolysis in a curd of soft cheese. During cheese manufacture, proteolysis occurred as soon as the renneting stage with the action of the chymosin, and the level of proteolysis intensified rapidly. The peptides, present within the whey collected throughout the drainage, were identified using tandem mass spectrometry. From the sixteen peptides identified at the first turn, we showed the early predominant action of the lactocepin type III. From the forty eight peptides identified at the end of the drainage, we demonstrated, in addition to the predominant action of lactocepin, other activities that could result from the action of lactococcal peptidases. In addition, this study of proteolysis confirmed that the action of proteinases on casein in solution differed from their action in situ: some sites cleaved in solution were not cleaved in cheese and vice versa.