Affected by the inner properties and the external environmental conditions, medicinal and edible lotus seeds are susceptible to mildew with fungal infection under suitable temperature and humidity conditions, leading to the production and contamination of various mycotoxins, along with threats to its quality and safety. In this study, the changes of water content (Cw) and water activity (Aw) of lotus seeds stored at 25 °C and different relative humidity conditions, as well as the correlation between them and mildew of this edible and medicinal material were studied, aiming to explore the safe Cw and Aw control points for screening out the suitable storage conditions from mildew. Blank (without fungal conidia) and experimental (artificially added with Aspergillus flavus conidia) groups of lotus seeds were stored at 25 °C and relative humidity of 40%, 50%, 60% and 70% for about 30 days, respectively. The mildew was observed and the changes of Cw, Aw, together with the production of aflatoxins were measured. Results showed that no mildew was found and aflatoxins were not detected in lotus seeds when they were stored for 30 days at 25 °C and relative humidity of 40%, 50% and 60% with Cw < 12% and Aw < 0.6. While, when the relative humidity was up to 70%, the Cw and Aw values rose quickly, and the Cw exceeded the officially-permitted level (14%). Although no mildew was observed, AFB1 was still detected, increasing the potential risk of lotus seeds regarding aflatoxins. For warranting the quality with economic and safe storage, lotus seeds are suggested to be stored at 25 °C and relative humidity lower than 60% with 12% and 0.6 as the safe Cw and Aw control points, respectively, to prevent medicinal and edible products from mildew and the contamination of aflatoxins.

中文翻译：

---

探索霉菌药用和食用莲子的安全含水量和活性控制点。

受内部特性和外部环境条件的影响，药用莲子和食用莲子在合适的温度和湿度条件下易受霉菌感染，并引起真菌感染，导致各种霉菌毒素的生产和污染，并威胁其质量和安全性。在这项研究中，研究了在25°C和不同相对湿度条件下储存的莲子的含水量（Cw）和水分活度（Aw）的变化，以及这种食用和药用材料与霉菌的相关性，旨在探索安全的Cw和Aw控制点，以从霉菌中筛选出合适的储存条件。空白（无真菌分生孢子）和实验（人工添加黄曲霉分生孢子）组的莲子分别在25°C和40％，50％，60％和70％的相对湿度下存储约30天。观察霉变，并测量Cw，Aw的变化以及黄曲霉毒素的产生。结果表明，当荷花种子在25°C且相对湿度分别为40％，50％和60％，Cw <12％和Aw <0.6的条件下存放30天时，未发现发霉现象，也未检出黄曲霉毒素。而当相对湿度高达70％时，Cw和Aw值迅速上升，并且Cw超过了官方允许的水平（14％）。尽管未观察到霉变，但仍检测到AFB1，增加了莲子黄曲霉毒素的潜在风险。