Contribution of specific adventitious microorganisms toward evolution of sugar and organic acid profiles throughout ripening of model Portuguese cheeses

Model cheeses, designed to mimic Portuguese traditional cheeses, were manufactured aseptically following a method that attempted to resemble artisanal manufacture practices: they were coagulated with either animal or plant rennet, and inoculated with defined strains of lactic acid bacteria, that had initially been recovered as major constituents of the native microflora of Serra da Estrela cheese, viz. Lactococcus and Lactobacillus genera, either independently or as a mixture. The gross composition, the microbial viability, and the organic compound profile in those model cheeses were monitored, throughout a 60 day-ripening period. Microbial viability, pH, and levels of acetic and lactic acids were the physicochemical and biological parameters that experienced the most significant changes in such matrices - which were, in turn, dependent on the type of inoculum used. No synergisms emerged upon combination of the two strains, in terms of sugar uptake and organic acid release. The contribution of each adventitious bacterium - either independently or in the presence of each other, to the development of expected biochemical characteristics of model cheeses (even though to a lower extent than in actual ones) was confirmed, whereas the type of rennet used proved to be not relevant.