Effects of Temperature and Humidity on Fungal Occurrence in Dried Red Pepper during Storage

Abstract

Dried red peppers are frequently contaminated with mycotoxins during storage. To determine the effect of storage environments on fungal occurrence and subsequent mycotoxin accumulation in dried red peppers, we monitored red pepper powder and whole fruit samples for fungal occurrence under various temperatures and relative humidity (RH) conditions during 340 days. Fungal occurrences fluctuated in both pepper forms throughout the storage but they were higher in pepper powder than whole one, higher under low temperatures (-20°C, 0°C, or 4°C) than others (10°C, 25°C, or 30°C), and higher under RH 93% than RH 51% and 69% in both peppers. The samples exhibiting high fungal occurrences were associated mainly with dominant species such as Aspergillus sydowii, Penicillium solitum, P. roqueforti, P. polonicum, or P. chrysogenum. Mycotoxigenic species, including A. flavus, A. ochraceus, A. westerdijkiae, A. tubingensis, and P. citrinum, were also detected throughout the samples. Although mycotoxins were not detected in the samples, mycotoxigenic potential of A. flavus, A. ochraceus, and A. westerdijkiae isolates were confirmed. These results show that low temperatures (-20°C, 0°C, or 4°C) and/or high surrounding RH (>93%) are not safe environments for storage of dried red peppers as fungal growth can occur under these conditions.