Purdue Improved Crop Storage (PICS) bags are used by farmers in Sub-Saharan Africa for pest management of stored grains and products, including maize. These bags hermetically seal the products, preventing exchange with external moisture and gases. Biological respiration within the bags create an environment that is unsuitable for insect development and fungal growth. This study was conducted to determine the impact of routine opening of the storage bags for maize consumption on fungal growth and aflatoxin contamination. Maize with moisture contents (MC) high enough to support fungal growth (15%, 16%, 18% and 20%) was stored in PICS bags, which were opened weekly and exposed to humid conditions (85% RH) for 30 min over a period of 8 weeks and 24 weeks. Monitors indicated that oxygen defused into the open bags but did not reach equilibrium with the bottom layers of grain during the 30-min exposure period. Fungal colony forming units obtained from the grain surface increased 3-fold (at 15% MC) to 10,000-fold (at 20% MC) after 8 weeks. At both 8 weeks and 24 weeks, aflatoxin was detected in at least one bag at each grain moisture, suggesting that aflatoxin contamination spread from a planted source of A. flavus-colonized grain to non-inoculated grain. The results indicate that repeatedly breaking the hermetic seal of the PICS bags will increase fungal growth and the risk of aflatoxin contamination, especially in maize stored at high moisture content. This work also further demonstrates that maize should be properly dried prior to storage in PICS bags.

中文翻译：

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打开密封储存袋对谷物品质、真菌生长和黄曲霉毒素积累的影响

撒哈拉以南非洲地区的农民使用普渡改良作物储存 (PICS) 袋对储存的谷物和产品（包括玉米）进行病虫害管理。这些袋子密封产品，防止与外部水分和气体交换。袋子内的生物呼吸创造了一个不适合昆虫发育和真菌生长的环境。本研究旨在确定常规打开用于食用玉米的储存袋对真菌生长和黄曲霉毒素污染的影响。将水分含量 (MC) 高到足以支持真菌生长（15%、16%、18% 和 20%）的玉米储存在 PICS 袋中，每周打开并暴露在潮湿条件（85% RH）中 30 分钟以上为期 8 周和 24 周。监测器表明，在 30 分钟的暴露期间，氧气会渗入打开的袋子中，但并未与谷物底层达到平衡。8 周后，从谷物表面获得的真菌菌落形成单位增加了 3 倍（15% MC）至 10,000 倍（20% MC）。在第 8 周和第 24 周，每个谷物水分至少有一个袋子检测到黄曲霉毒素，这表明黄曲霉毒素污染从种植的黄曲霉定植谷物源扩散到未接种的谷物。结果表明，反复破坏 PICS 袋的密封会增加真菌生长和黄曲霉毒素污染的风险，尤其是在高水分储存的玉米中。这项工作还进一步表明，玉米在储存在 PICS 袋中之前应适当干燥。