Patulin: Surveillance in Michigan apple cider and juice, and factors influencing its production and concentration in apple products

Patulin is produced by mold species such as Penicillium expansum and is the most abundant mycotoxin in apples and apple juice. Because of its toxicity, the FDA has established that patulin concentrations in apple juice products should not exceed 50 mug/kg. The objectives of this research were: (1) determine the concentrations of patulin in (a) apple cider produced and marketed by Michigan cider mills in 2002-2004 and (b) different brands of apple juice and cider, including shelf-stable products, marketed in retail grocery stores in Michigan in 2005-2006, (2) determine the production of ethylene by P. expansum and the relationship between the presence of endogenous and exogenous ethylene and patulin production by P. expansum on liquid and solid media, (3) determine whether fruit-produced ethylene or exogenous ethylene (100 muL/L) affects the production of patulin in apples treated with 1-methylcyclopropene (1-MCP) and inoculated with P. expansum, and (4) determine the effect of trimming and culling of apples inoculated with P. expansum on patulin levels in intact and decayed apple tissue and in juice produced from two varieties of apples. To achieve these objectives, we (1) surveyed cider and juice samples from Michigan mills (N=493) retail grocery stores (N=159) for patulin concentrations, (2) analyzed the effects of ethylene and 1-MCP on patulin production in Red Delicious apples and liquid and solid media inoculated with P. expansum, and (3) evaluated the effects of trimming and culling on patulin concentrations in juice from naturally-infected Red Delicious apples and manually inoculated ( P. expansum) Jonagold and Red Delicious apples stored in normal atmosphere for up to 15 days.; The survey confirmed detectable patulin (≥4 mug/L) in 18.7% of all cider mill samples with 2.2% of samples above the legal limit of 50 mug/L. In retail grocery stores, 23% contained detectable patulin, with 11.3% of samples having patulin concentrations above the legal limit. Exogenous ethylene administration significantly promoted patulin production by P. expansum when inoculated on solid Potato Dextrose Agar media (P ≤ 0.0206) and tended to promote (P ≤ 0.065) patulin production by P. expansum when inoculated on apples. 1-MCP treatment of apples throughout P. expansum growth did not influence patulin production in either medium. Juice extracted from rotten tissue of apples inoculated with P. expansum in the laboratory typically contained >1000 mug patulin/L by six days after inoculation. Juice prepared from normal appearing tissue of both Jonagold and Red Delicious apple varieties always contained detectable patulin by nine days after inoculation, but patulin concentrations in this normal-appearing tissue never exceeded 100 mug/L.; These experiments demonstrated that (1) apple cider and juice processors need to improve patulin control procedures, (2) exogenous ethylene treatment does not inhibit, and may actually enhance, patulin production by P. expansum, and (3) that careful trimming and culling of fruit used for juice production is highly effective in controlling patulin concentrations in apple juice, provided that removal of decayed apple flesh is essentially complete.