Exploring the Efficacy of Ochratoxinase Treatment in Grape-Derived Products: A Feasible Approach for Grape and Dried Vine Fruit OTA Detoxification

Abstract Ochratoxin A (OTA) is a mycotoxin commonly found in many food products. Grape-derived food products represent the second largest source of daily OTA intake. As an alternative to chemical and physical processes for OTA detoxification, there is growing interest in the use of enzymatic treatments. The biodegradation of OTA by enzymes is a highly specific and environmentally friendly treatment. This study investigated the effect of grape and wine compounds on the OTA-degrading activity of microbial amidohydrolases (ochratoxinases) from Aspergillus niger ( An OTA) and Brevibacterium linens ( Bl OTA), microorganisms that have “Qualified Presumption of Safety” (QPS) or “Generally Recognised As Safe” (GRAS) status. Malic and tartaric acids, as well as reducing sugars, inhibit ochratoxinase activity at concentrations found in grape juices. The effect of these compounds could be partly responsible for the lower ochratoxinase activity observed in synthetic grape juice compared with synthetic dealcoholised wine, although the acidic pH was the main factor responsible for enzyme inhibition in both synthetic beverages. Incubation with Bl OTA ochratoxinase was an effective treatment for the detoxification of table grapes and dried vine fruits superficially contaminated with OTA, thus providing a solution to the problem of the presence of this mycotoxin in grape-derived products. The Bl OTA’s limited activity at acidic pH makes it unsuitable for its direct use in grape juices and wines. This initial approach to exploring an enzymatic treatment for OTA detoxification in grape products paves the way for future development of acidophilic variants, in order to expand their potential industrial applications.