The aim of this study was to characterise flavour differences between short-ripened Gouda-type cheeses produced from raw and pasteurised milk and to follow, in the case of pasteurised milk cheeses, flavour evolution during ripening. The volatile composition of the cheeses was studied using a combination of simultaneous steam distillation-extraction and gas chromatography-mass spectrometry. Visualisation of the analytical results was performed by principal component analysis. A clear differentiation between raw milk cheese and pasteurised milk cheese was observed and the evolution of the volatile composition of the pasteurised cheese samples during ripening was clearly demonstrated. Partial least squares regression was used to examine possible relationships between the chemical-analytical and sensory descriptive data. r

Raw milk cheeses have more intense flavours than cheeses made from pasteurized milk and harbour strains with potential adjunct properties. Two Lactobacillus paracasei strains, R-40926 and R-40937, were selected as potential adjunct cultures from a total of 734 isolates from good quality artisan raw milk Gouda-type cheeses on the basis of their prevalence in different cheese types and/or over several production batches, safety and technological parameters. Conventional culturing, isolation and identification and a combined PCR-DGGE approach using total cheese DNA extracts and DNA extracts obtained from culturable fractions were employed to monitor viability of the introduced adjuncts and their effect on the cheese microbiota. The control cheese made without adjuncts was dominated by members of the starter, i.e. Lactococcus lactis and Leuconostoc pseudomesenteroides. In the cheeses containing either R-40926 or R-40937, the respective adjuncts increased in number as ripening progressed indicating that both strains are well adapted to the cheese environment and can survive in a competitive environment in the presence of a commercial starter culture. Principal component analysis of cheese volatiles determined by steam distillation-extraction and gas chromatography-mass spectrometry could differentiate cheeses made with different concentrations of adjunct R-40926 from the control cheese, and these differences could be correlated to the proteolytic and lipolytic properties of this strain. Collectively, results from microbiological and metabolic analyses indicate that the screening procedure followed throughout this study was successful in delivering potential adjunct candidates to enrich or extend the flavour palette of artisan Gouda-type cheeses under more controlled conditions.

No abstract

No abstract