Mycotoxins are ubiquitous on the basis of global surveillance of mycotoxin contamination in cereal-based food. Deoxynivalenol (DON), a mycotoxin produced by Fusarium spp. in the field, has been found with the greatest frequency in cereal-based food. The common way to control DON in food manufacture is to avoid the utilization of the mycotoxin contaminated grains, which oftentimes is not applicable. For example, previous studies have shown that DON levels can increase appreciably during the malting of so-called “clean grains” and that newly produced DON can be transferred to beer. The hops themselves, or the extracted oil, are extensively used in beer production for providing bitterness and characteristic aroma. Therefore, we explored the efficacy of hop oil nanoemulsion on Fusarium graminearum growth, mycotoxin production and understand their mechanisms of action on fungi membrane. The major chemical composition of hop essential oil was humulene, followed by beta-myrcene, caryophyllene, nerol and 3,3,6-Trimethyl-1,5-heptadiene. The 5 wt% of hop oil-in-water nanoemulsion could be fabricated by incorporating 70 wt% of hop oil with 30 wt% of medium chain triacylglycerol (MCT) in oil phase prior to homogenization. The hop oil-in water nanoemulsion with mean diameter < 145 nm showed highly stable against droplet growth during 30 days storage. The antifungal activities of hop nanoemulsion against mycelial growth and spore germination was dose dependent. The inhibition of F. graminearum growth was mainly attributed to increased lipid content of cell membrane, disputed cell wall composition and impaired cell viability as observed by three different fluorescent probes. Regarding mycotoxin inhibitory efficacies, 90% of mycotoxin production could be inhibited by applying 750 μg/g hop oil nanoemulsion in rice cultures. The results of this study have important implications for the design and utilization of hop oils as natural antifungal agents and mycotoxin inhibitors in the food industry.

ACKNOWLEDGEMENT AND DISCLAIMER

This material is based upon work supported by the This material is based upon work supported by the U.S. Wheat and Barley Scab Initiative under Agreement No. 59-0206-8-212 and USDA National Institute of Food and Agriculture (FAR0032822). Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.