Application of atmospheric pressure cold plasma to sanitize oak wine barrels

Abstract

Oak wood barrel sanitization is crucial in terms of food safety, since barrels enrich the wine in aromas and taste sensation and provide physico-chemical stability. The most used method is barrel sulphuring; however, there is a European prohibition (Directive 98/8/CE2) that does not allow the use of this method. For this reason, the aim of the present work was to study an alternative technology, the atmospheric pressure cold plasma (APCP) to sanitize oak wood staves. Three wine spoilage microorganisms, two bacteria (Pediococcus pentosaceus and Acetobacter pasteurianus) and a yeast (Brettanomyces bruxellensis), were inoculated in the wood staves. Then, they were exposed to APCP device at a 12-passes treatment with different plasma powers (90 W and 500 W) and plasma gases (air, nitrogen and argon). A total inactivation of the yeast was achieved after the air and nitrogen plasma treatments, being the most sensitive microorganism to the APCP. In terms of bacteria, P. pentosaceus and A. pasteurianus showed a lower inactivation with respect to their controls. The reactive oxygen and nitrogen species generated during the plasma generation process seem to play the main role on the microbial inactivation. Finally, no morphological modifications on the wood surface were identified after APCP treatments.