Exploration of the safe water content and activity control points for medicinal and edible lotus seeds from mildew

Abstract

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.

Sampling locations and processing methods shape fungi microbiome on the surface of edible and medicinal Arecae semen

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Single-Molecule Real-Time Sequencing to Explore the Mycobiome Diversity in Malt

“…The a w is a significantly important factor affecting fungal growth and fungal communities ( 46 ). Therefore, the a w values of the 20 samples were determined using an HD-6 intelligent moisture activity measuring instrument (Wuxi Huake Instrument, Wuxi, China).…”

Evaluation of the Susceptibility of Lotus Seeds (Nelumbo nucifera Gaertn.) to Aspergillus flavus Infection and Aflatoxin Contamination

“…Nevertheless, the abundant amounts of proteins and polysaccharides in lotus seeds result in their susceptibility to infection with toxigenic fungi in the preharvest, postharvest, processing, storage, and transportation processes under appropriate humidity and temperature conditions [ 2 , 6 ], especially during the rainy season, leading to the production and residue of various mycotoxins [ 7 ].…”