Rapid volatile metabolite profiling of Lactobacillus casei strains : selection of flavour producing cultures

A technique based on an electronic nose combined with multivariate analysis was used to select bacterial strains of Lactobacillus casei as flavour producing adjunct cultures. Volatile metabolites were extracted from a suspension of bacterial cultures incubated with amino acids using inside-needle extraction and headspace sampling. The extracts were then injected into a mass spectrometry-based electronic nose. Mass fragmentation patterns from the unresolved volatile components were subjected to multivariate data analysis. Principal component analysis (PCA) allowed differentiation of bacterial strains. Based on these results, bacterial strains were selected as adjunct cultures for cheesemaking. After a six-month ripening period, cheeses were analysed by gas chromatography and found to contain higher amounts of aroma contributing components than control cheeses.