A Preliminary Mycological Evaluation of Organic and Conventional Foods

Selected conventional and organic foods were surveyed during the period 2009–2013. A total of 100 samples (50 conventional and 50 organic) were purchased from grocery stores and farmers’ markets in southeastern Pennsylvania. The products investigated were popcorn, rice, corn, walnuts, almonds, peanuts, pumpkin seeds, green peas, flaxseeds, soybeans and cashew nuts. Direct plating was used in the study, with the following media: MEA, DRBC, DG18 and AFPA. After samples were incubated at 25°C for 3–5 days, the results were expressed as percentage of food particles infected by molds. Selected mold isolates were tested for the production of mycotoxins in laboratory media, and all food samples were screened for aflatoxin. The results of this preliminary study demonstrate no significant difference in the levels of mold contamination between organic and conventional samples. Twenty-two mold species representing eleven different genera have been identified. The most dominant mold genera were Aspergillus, Penicillium, Alternaria and Cladosporium. Some of the species identified have been found to produce their respective mycotoxins in laboratory media. A few samples in each food category were found to contain aflatoxins. There was no significant difference in mycotoxin production between mold species isolated from organic samples and those isolated from conventional samples.