부산대학교 도서관

Aspergillus flavusmay colonize hazelnuts and produce aflatoxins in the field and during storage. The main purpose of this study was to investigate the influence of drying temperature and exposure times on the viability of A. flavusand its ability to produce aflatoxins during the drying process and storage. Hazelnuts were inoculated with A. flavusand dried at different temperatures to reach 6% moisture content and a water activity (aw) of 0.71, a commercial requirement to avoid fungal development and aflatoxin contamination. Hazelnuts were dried at 30, 35, 40, 45, and 50°C and subsequently stored at 25°C for 14 days. After drying at 30, 35, and 40°C, increased amounts of A. flavuswere evident, with the highest concentration occurring after drying at 35°C ([6.1 ± 2.4] × 106A. flavusCFU/g). At these temperatures, aflatoxins were detected only at 30 and 35°C. Aflatoxins, however, were present at higher levels after drying at 30°C, with concentrations of 1.93±0.77 μg/g for aflatoxin B1(AFB1) and 0.11±0.04 μg/g for aflatoxin B2(AFB2). After 14 days of storage, the highest A. flavusconcentration and the highest levels of mycotoxins were detected in samples treated at 35°C ([8.2 ± 2.1] × 107A. flavusCFU/g and 9.30±1.58 μg/g and 0.89±0.08 μg/g for AFB1and AFB2, respectively). In hazelnuts dried at 45 or 50°C, no aflatoxins were found either after drying or storage, and a reduction of A. flavusviable conidia was observed, suggesting that a shorter and warmer drying is essential to guarantee nut safety. The lowest temperature that guarantees the lack of aflatoxins should be selected to maintain the organoleptic quality of hazelnuts. Therefore, 45°C should be the recommended drying temperature to limit A. flavusgrowth and aflatoxin contamination on hazelnuts.