Fungal isolation and causal organisms of zearalenone contamination from Job's tears seeds and the products

Abstract

Seeds of Job's tears (Coix lachryrna jobi var. ma-yuen) are commonly used as herbal drug and health food in Japan, but mycotoxin contamination such as aflatoxin and zearalenone (ZEN) on Job's tears products is often problematic. Thus, a mycological examination on 35 samples of raw seed materials and commercial products of Job's tears was carried out. Aspergillus flavus, Curvularia spp., Bipolaris coicis, Fusarium pallidoroseum (=F. semitecturn), F. equiseti and F. moniliforme were detected as predominant fungi in the samples. Of the Fusarium species isolated, F. pallidoroseurn was most dominant. ZEN producing ability of these Fusariunn isolates on seeds of Job's tears in cultures was measured by HPLC analysis. The isolates of F. pallidoroseum, F. equiseti and F. moniliforme produced ZEN, with maximum yields of 55, 244 ng/g, 137 ng/g and 54 ng/g, respectively. Among tested 12 samples of the commercial Job's tears products, ZEN contamination was found in 3 hulled seeds (21; 25; and 44 ng/g), 2 crucked products (6; 29 ng/g) and 3 powdery products (23; 46 and 116 ng/g).