Ting W T Evert, Chang Chih-Hsuan, Szonyi Barbara, Gizachew Dawit
Department of Biological Sciences, Schererville, Indiana, USA.
Independent Consultant, Schererville, Indiana, USA.
J Food Prot. 2020 Jun 1;83(6):975-983. doi: 10.4315/JFP-19-539.
Flax seed has become an increasingly popular food ingredient because of its nutrient richness as well as potential health benefits. Flax seeds are often ground before consumption, and flax seed cakes are used as animal feed. Aflatoxin production may occur subsequently when the ground seeds are stored in an environment that supports fungal growth. The objectives of this study were to determine the growth of two toxigenic fungi, Aspergillus flavus and A. parasiticus, and to quantify the concentrations of four major aflatoxins (AFB1, AFG1, AGB2, and AFG2) produced by the two fungi on ground flax seeds with water activities (aws) of 0.82, 0.86, 0.90, 0.94, and 0.98, incubated for 30 days at 20, 27, and 35°C. Results of the study showed that A. flavus was able to grow on ground seeds with aw from 0.86 to 0.98 at all three temperatures, and the most rapid growth occurred at aws 0.90 and 0.94 at 27°C. In comparison, A. parasiticus grew on seeds with aw from 0.86 to 0.98 at 27 and 35°C as well as on seeds with aw from 0.86 to 0.90 at 20°C, and the most favorable growth condition was aw from 0.90 to 0.94 at 35°C. A. flavus produced aflatoxins on seeds with aw from 0.90 to 0.94 at 27°C as well as on seeds with aw from 0.86 to 0.98 at 35°C, and the maximum total aflatoxin (298 μg/kg), AFB1 (247 μg/kg), and AFG1 (51 μg/kg) were found on seeds with aw 0.90 at 35°C. In comparison, A. parasiticus produced aflatoxins under a wider range of conditions, which included aw 0.86 at 27 and 35°C, aw 0.90 at 20 and 27°C, aw 0.94 at 27°C, and aw 0.98 at 35°C. The maximum total aflatoxin (364 μg/kg) and maximum AFB1 (324 μg/kg) along with 34 μg/kg AFG1 and 6 μg/kg AFB2 were produced by A. parasiticus on seeds with aw 0.98 incubated at 35°C for 30 days. Linear regression models also indicated that high incubation temperature (35°C) was optimal for overall fungal growth and for formation of high levels of aflatoxin by both fungi. Future studies should also address aflatoxin contamination in flax seed oil.
亚麻籽因其营养丰富以及潜在的健康益处，已成为越来越受欢迎的食品成分。亚麻籽通常在食用前磨碎，亚麻籽饼用作动物饲料。当磨碎的种子储存在有利于真菌生长的环境中时，随后可能会产生黄曲霉毒素。本研究的目的是确定两种产毒真菌——黄曲霉和寄生曲霉的生长情况，并量化这两种真菌在水分活度（aw）分别为0.82、0.86、0.90、0.94和0.98的磨碎亚麻籽上，于20、27和35°C下培养30天所产生的四种主要黄曲霉毒素（AFB1、AFG1、AGB2和AFG2）的浓度。研究结果表明，黄曲霉在所有三个温度下都能在水分活度为0.86至0.98的磨碎种子上生长，在27°C时，水分活度为0.90和0.94时生长最快。相比之下，寄生曲霉在27和35°C下能在水分活度为0.86至0.98的种子上生长，在20°C下能在水分活度为0.86至0.90的种子上生长，最适宜的生长条件是在35°C下水分活度为0.90至0.94。黄曲霉在27°C下水分活度为0.90至0.94的种子上以及在35°C下水分活度为0.86至0.98的种子上产生黄曲霉毒素，在35°C下水分活度为0.90的种子上发现的总黄曲霉毒素最高（298μg/kg）、AFB1（247μg/kg）和AFG1（51μg/kg）。相比之下，寄生曲霉在更广泛的条件下产生黄曲霉毒素，包括27和35°C下水分活度为0.86、20和27°C下水分活度为0.90、27°C下水分活度为0.94以及35°C下水分活度为0.98。寄生曲霉在35°C下将水分活度为0.98的种子培养30天，产生的总黄曲霉毒素最高（364μg/kg）和最大AFB1（324μg/kg），以及34μg/kg AFG1和6μg/kg AFB2。线性回归模型还表明，高温培养（35°C）最有利于两种真菌的总体生长和高水平黄曲霉毒素的形成。未来的研究还应关注亚麻籽油中的黄曲霉毒素污染问题。
