Traditional fermented sausage 'Nem chua' as a source of yeast biocatalysts efficient for the production of the aroma compound γ-decalactone

The yeast ecosystem of Nem chua, a Vietnamese traditional fermented sausage naturally rich in medium-chain-length lipid-derived flavouring compounds, was investigated to select biocatalysts able to produce the C10-fatty acid-derived aroma compound -decalactone. The total number of yeast was about 5x10(4) to 4x10(5)CFUg(-1), and eighty four different species were identified from morphological, physiological and 26S rDNA characteristics, with Candida sake and Candida haemulonii being found in all samples. Six strains able to produce -decalactone from castor oil were selected, of which three Yarrowia lipolytica strains were able to produce between 1 and 2gL(-1) in our study. The strains produced the same amount from the acyl substrate under the form of ester or free fatty acid. Every strain degraded the product at the end of the culture. These high productions make them good candidates for industrial processes and confirm that traditional fermented foods are interesting bioresources for biocatalysts.