Ability of meat starter cultures to catabolize leucine and evaluation of the degradation products by using an HPLC method

The degradation of leucine generates aroma compounds involved in the typical flavour of dry fermented sausage. The ability of lactic acid bacteria and staphylococci of meat origin to produce aromatic compounds from leucine was studied. Whole cells were incubated with H-3-labelled leucine under different conditions The radioactive metabolites produced were analysed by high performance liquid chromatography. All the strains studied were able to catabolise leucine but catabolic profiles were quantitatively and qualitatively different. The catabolism of leucine by Lactobacillus sakei Lactobacillus curvatus and Pediococcus acidilactici was very low and required alpha-ketoglutarate, which indicates that an aminotransferase was involved in the first step of leucine catabolism. Carnobacterium piscicola produced a large amount of 3-methyl butanal, whereas Staphylococcus carnosus mainly produced 3-methyl butanoic acid. Leucine was mainly degraded into alpha-ketoisocaproic acid by Lactobacillus plantarum and Carnobacterium divergens. Nitrate affected leucine catabolism only in S. carnosus. (C) 2000 Academic Press.