Microbiological diversity in natural whey starters used to make traditional Rocamadour goat cheese and possible relationships with its bitterness [France]

Abstract

Rocamadour is a farmhouse-made cheese that is based on the use of a natural whey starter (NWS). Eight NWS from seven different cheese houses were analysed, mainly for their lactic acid bacteria population, because bitterness has become a problem. The isolates were identified on the basis of phenotypic and biochemical capacities. Lactococci were often the most abundant microflora followed by Leuconostoc, with levels ranging from 10 8 to 10 9 cfu/mL. Citrate-positive bacteria levels were about the same. In particular, the Lactococcus lactis subsp. cremoris levels were always greater than those of Lc lactis subsp. lactis cases, except in the two NWS suspected of causing bitterness. Leuconostoc mesenteroides subsp. mesenteroides and Ln mesenteroides subsp. cremoris were the only two subspecies identified. The technological characterisation of 165 lactococci and leuconostocs and the analysis of whole-cell protein patterns allowed different bacterial behaviours to be observed. In some NWS, a few strains were dominant whereas in some others, the microflora was more diverse.