Distinct Distribution of Deoxynivalenol, Nivalenol, and Ergosterol in Fusarium-infected Japanese Soft Red Winter Wheat Milling Fractions

Abstract

The occurrence of mycotoxins in small grain cereals and their retention in final products are serious concerns for food safety. Previously, we investigated the fate of deoxynivalenol and nivalenol in a Japanese soft red winter wheat cultivar during milling and we found that deoxynivalenol and/or nivalenol was readily distributed among flours for human consumption. In the present study, we analyzed the ergosterol concentrations in the milling fractions as an index of fungal biomass to elucidate the relationship between deoxynivalenol/nivalenol accumulation and fungal invasion into the grain, after the in-house validation of an analytical method for quantifying ergosterol in the resulting milling fractions (patent flour, low-grade flour, bran, and shorts). Using three samples with different levels of deoxynivalenol and/or nivalenol contamination, the contents of deoxynivalenol/nivalenol and ergosterol in the resulting milling fractions were evaluated. The concentration of ergosterol was always lowest in patent flour and highest in bran or shorts, indicating that most of the fungi is retained in the outer layers of grain (bran and shorts) even in highly contaminated grain. On the other hand, the concentrations of deoxynivalenol and nivalenol were similar in the low-grade and patent flours and only slightly lower than in the medium-level and high-level contaminated grains. Moreover, the percentage distribution of ergosterol was higher in bran than in other fractions in all cases, which differed from that of deoxynivalenol/nivalenol. This result indicates the diffusion of deoxynivalenol/nivalenol inside the grain that is independent of fungal invasion.

Scientific Opinion on the risks to human and animal health related to the presence of beauvericin and enniatins in food and feed

“…Vaclavikova et al (2013) conducted a milling experiment (with a laboratory mill) with conventionally and organically farmed wheat, naturally contaminated with enniatin B and enniatin B1 at rather low levels (119 and 26 μg/kg for conventionally grown wheat, and 38 and 22 μg/kg for organically grown wheat). The findings are very similar to those found for deoxynivalenol and other Fusarium mycotoxins (Bullerman and Bianchini, 2007;Thammawong et al, 2011). The highest concentrations of enniatins were detected in shorts and bran, and substantial reductions for enniatin concentrations were observed in processed white flour.…”

Wet milling technique applied to deoxynivalenol‐contaminated wheat dry‐milled fractions

“…For late infection, the time for Fusarium invasion probably was too short for high levels of hyphae to occur in the endo sperm. These findings support previous research about the lower levels of DON in wheat endosperm, while the highest concentration of DON levels was found in wheat bran (Cheli et al, 2010;Thammawong et al, 2011;Tibola et al, 2015;Visconti et al, 2004).…”

The Fate of Mycotoxins During the Processing of Wheat for Human Consumption

“…The difference in the concentration of mycotoxins in distinct grain tissues is considered to be to a certain degree related to the colonization pattern of the molds. Colonization is usually higher in outer grain layers and lower in the inner tissues (Young et al., ; Nowicki et al., ; Thammawong et al., ; Tibola, Fernandes, Guarienti, & Nicolau, ). The fungal growth and its ability to colonize the inner grain tissues depend, for example, on the susceptibility of the cereal cultivar, but also on the weather conditions during the season and can thus strongly vary over years.…”