Trichoderma atrobrunneum associated with yellow stain defect of cork planks and critical values of TCA for wine cork stoppers industry

Cork planks with Yellow Stain (YS) defect are rejected from cork-stopper factory industries resulting in large economical losses. This defect has been related to 2,4,6—trichloroanisole (TCA), a chemical compound responsible for an off-flavor aroma in wine known as cork taint. The relation between YS and TCA was confirmed by the analyzes carried out in this work. Considering that fungi have the capacity to convert trichlorophenol into TCA, raw cork planks were collected in a factory and the mycobiota was searched using morphological and molecular methods. Eight genera and order of fungi were obtained and statistical analysis revealed that the Trichoderma genus is significantly related to TCA levels critical for industry, in particular the species Trichoderma atrobrunneum, a fungus belonging to Trichoderma harzianum complex. To our knowledge, this is the first report associating T. atrobrunneum to high TCA levels and YS defect of cork.