Possible toxicological risk arising from contamination of grapes and derivatives by emerging mycotoxins: patulin

Exposure to mycotoxins through the food chain has been a well-known problem for a long time. The number of molecules belonging to this category has been progressively increasing, making it difficult to quantify and correctly assess the toxicological risk. Contamination of wine by mycotoxins was underestimated until the end of the last century when, in many geographical areas, the presence of moulds producing ochratoxin A in vineyards and consequently in grapes and derivatives was highlighted. Following the acquired awareness, actions were undertaken to contain this contamination, and attempts were made to evaluate the presence of any other mycotoxins. Some authors have therefore searched for and reported the presence of other molecules of this class, including aflatoxins, patulin and fumonisins. Mycotoxins are secondary metabolites produced by fungi in particular environmental conditions that can be defined as "stressing". Among these, patulin is classified by IARC in group 3, that is, among those substances for which there is not sufficient evidence of a carcinogenic effect. However, this mycotoxin represents a real risk to the health of the consumer, since it can cause simple disorders of the gastrointestinal tract but also kidney, liver, neurological problems and compromise of the immune system. The presence of patulin in some food (mainly apple derivatives) has been reported by several authors and to guarantee the health of the consumer, in many parts of the world (including the EU and the USA) a maximum limit of 50 μg/kg has been set in fruit juices and in the related concentrate. In the case of products aimed at children, the limit drops to 10 μg/kg. The aim of this presentation is to collect and critically evaluate the available knowledge on the presence of patulin in grapes and its derivatives with particular attention to wine, for which less information is available. The literature search was performed using the most important scientific databases, including PubMed, Embase, Web of Science and CabAbstract from 1970 to 2025. The keywords used were "wine/must/grape" in combination with "patulin/mycotoxins". Data on the presence of patulin in foods mostly concern apples and derivatives, as it was the first food for which awareness of a possible health risk was acquired. Our group has also dealt with this topic in the past. As regards grapes and derivatives, some scientific papers have reported the presence of patulin with extremely variable values in relation to the geographical area considered. In Pakistan, a mycotoxin content of 53.9±98.5 μg/kg was reported in fresh grapes, and in grape must/juice a concentration varying between not determinable and 750 μg/kg. In Germany, values of 4.9-5.2 μg/kg were determined in grape juice and 3.5-80 μg/kg in grape must. Other authors from the Czech Republic analysed 23 must samples, finding the presence of patulin in 10 of them with a concentration range of 143-644 μg/kg. The same authors measured the mycotoxin in wines derived from the musts mentioned above: in all cases the concentration was lower than 10 μg/kg. They therefore assumed that the mycotoxin can be significantly degraded in fermentation processes. The assessment of papers found in the literature indicates that the grape and derivatives sector has only rarely been included among the foods/drinks in which the patulin mycotoxin has been quantified. The conclusions that can be drawn indicate that the products to which greater attention must be paid are fresh grapes and must. Based on the few available studies, wine should be less frequently contaminated by patulin, perhaps due to fermentation, which is able to eliminate it. This knowledge should however be confirmed by new studies, since, although not considered carcinogenic, patulin can have significant toxic effects in humans.