Studies on the microflora, aflatoxin, and p-aminobenzoic acid content of peanut fruits from Mexico and the influence of selected gases on aflatoxin production in peanuts by Aspergillus flavus link

Abstract

Sound, Mature peanut kernels grown in Mexico were examined for aflatoxin contamination previous to the normal harvest data and following storage. Peanut kernels were free of aflatoxins before harvesting but traces to high levels were found in stored peanuts. Fusarium spp. were more prevalent in kernels at harvest; however, following storage, fungi of the Aspergillus glaucus group were more commonly isolated. The efficacy was tested of Polyram, EL 305, PCNB, and Difolatan in controlling actively growing mycelium of Fusarium oxysporum, Rhizoctonia solani, and Sclerotium rolfsii. Results indicated that Difolatan had fungicidal effects against Fusarium oxysporum while EL 305 was most active against R. solani and S. rolfsii. Peanuts at kernel moisture contents of 48.9, 38.3, 36.9, 32.8, 25.4, 12.8, and 5.7 percent were inoculated with A. flavius and incubated under compressed air, 2-aminobutane, nitrogen, and a mixture of 87% CO₂, 13% N₂ for 9 days at 25 C. Compressed air and the mixed gas (87% CO₂, 13% N₂) allowed aflatoxin production in kernels with moisture contents of 32.8 and 25.4 percent. Peanut kernels stored under N₂ atmosphere developed an offensive odor. Peanut kernels stored under a 2-aminobutane atmosphere or washed with a liquid solution of the compound absorbed large quantities of the chemical. The p-aminobenzoic acid content of 15 peanut varieties grown in Mexico was determined by diazotizing and coupling an aqueous filtrate. The content of p-aminobenzoic acid was 15 ug for the variety Deschecho PNS and six other varieties contained more than 3.5 ug/g. The remaining 8 varieties contained p-aminobenzoic acid contents ranging from 0.5 to 3.0 ug/g.