Screening of aroma-producing electronic lactic acid bacteria with an nose

The potential of a mass spectrometry (MS) based electronic nose to screen lactic acid bacteria producing volatile compounds was assessed. Thirty four reference strains and 62 Lactobacillus casei strains isolated from 5 dairies producing Gruyere cheeses were analysed. These isolates were classified into 7 different genotypes by Repetitive extragenic palindromic Polymerase chain reaction (REP-PCR). The strains were incubated in Ultra High Temperature milk supplemented with casamino acids. After 10 days of incubation, the volatile fractions were analysed with the electronic nose. The strains with the same genotype were grouped together. The classification of strains based on the production of volatile compounds was in conformity with the classification obtained with the molecular method. This MS-based electronic nose can be used to differentiate bacterial populations in cheese samples and to screen for new aroma-producing strains. (C) 2004 Elsevier Ltd. All rights reserved.