The isolation of fungi from air and kiln drying oak wood used for the maturation of alcoholic beverages

This study is the initial part of a 4 year research programme to investigate the effects of cooperage processing parameters on Scotch whisky flavour. The aim of the study was to utilise cooperage toasting parameters and fungal isolates that occur naturally in the seasoning of oak wood to control the flavour of Scotch whisky. Following isolation from oak, organisms were screened using phenol oxidase and cellulase metabolic tests to evaluate the likelihood of an organism's ability to degrade oak wood and therefore release aroma congeners into maturing spirit. The results indicate that a sequence of organisms could be isolated from air seasoning oak that displayed changing metabolic activity with air drying time. Very few organisms could be isolated from kiln drying oak wood. This suggested that kiln drying may reduce mycoflora in oak wood. Results show that air seasoning exposes oak wood to organisms that can potentially release lignin and polysaccharide species into maturing beverages.