Volatile compounds produced by microorganisms isolated from cork

Microorganisms present on cork (i.e. the reproduction bark of Quercus suber L.) can produce odorous compounds a€ecting the quality of cork stoppers. This work aims to contribute to the study of the correlation between microbial growth and formation of volatile compounds in the cork. Di€erent strains of microorganisms were cultivated on both malt extract and cork, and the odour of the culture was described by a panel. The volatile compounds were isolated directly from the culture media by a dynamic headspace technique followed by adsorption on to Tenax traps. The volatiles were identi®ed by GC±MS: 63 substances were identi®ed in malt extract cultures, mainly consisting of carbonyl compounds (16), alcohols (16), and sesquiterpenes (13). Cultures on cork produced only 12 volatile compounds, more than half being sesquiterpenes. Sensory evaluation con®rmed that cork is an unfavourable culture medium if compared with malt extract.