Patulin contamination of hard apple cider by Paecilomyces niveus and other postharvest apple pathogens: assessing risk factors

Abstract

Hard apple cider is considered to be a low-risk product for food spoilage and mycotoxin contamination due to its alcoholic nature and associated food sanitation measures. However, the thermotolerant mycotoxin-producing fungus Paecilomyces niveus may pose a significant threat to hard cider producers. Pa. niveus is known to infect apples (Malus xdomestica), and previous research indicates that it can survive thermal processing and contaminate finished apple juice with the mycotoxin patulin. To determine if hard apple cider is susceptible to a similar spoilage phenomenon, cider apples were infected with Pa. niveus or one of three patulin-producing Penicillium species and the infected fruits underwent benchtop fermentation. Cider was made with lab inoculated Dabinett and Medaille dOr apple cultivars, and patulin was quantified before and after fermentation. Results show that all four fungi can infect cider apples and produce patulin, some of which is lost during fermentation. Only Pa. niveus was able to actively grow throughout the fermentation process. To determine if apple cider can be treated to hinder Pa. niveus growth, selected industry-grade sanitation measures were tested, including chemical preservatives and pasteurization. High concentrations of preservatives inhibited Pa. niveus growth, but apple cider flash pasteurization was not found to significantly impact spore germination. This study confirms that hard apple cider is susceptible to fungal-mediated spoilage and patulin contamination. Pa. niveus should be of great concern to hard apple cider producers due to its demonstrated thermotolerance, survival in fermentative environments, and resistance to sanitation measures. HighlightsO_LIApple fruits of traditional cider cultivars Dabinett and Medaille dOr were found to be susceptible to infection by three patulin-producing Penicillium spp. and Paecilomyces niveus C_LIO_LIPa. niveus can grow in finished fermented hard cider at 5.22% ethanol C_LIO_LIPatulin levels in cider were reduced by fermentation but still exceeded 50 {micro}g/kg, a maximum limit set by various regulatory agencies C_LIO_LIPa. niveus was observed to be able to grow in low concentrations of three preservatives: potassium sorbate, sulfur dioxide, and sodium benzoate C_LI