Study On The Control Of Mycotoxins By Essential Oils Fumigation In Maize

Accorrding to the World Health Organization (WHO), approximately20%of grain are lost everyyear, and more than half of them are caused by fungus and mycotoxins. Accorrding to Food andAgriculture Organization of United Nations (FAO), approximately25%of the world’s food crops arecontaminated by mycotoxins. The growth of fungus can not only cause the losses of grain, but alsoserious hazard to human health. Therefore, the detection and prevention of mycotoxins in food are ofconcern, especially aflatoxins and Fusarium toxins which are both regared as the most dangerous naturalfood contaminants by the FAO and the WHO.Aflatoxin (AFT), which is harmful to humans and animals, was found to be carcinogenic, mutagenicand teratogenic in food and feed. And AFB1, one kind of AFT, is the strongest carcinogen mycotoxin everdiscovered. The toxigenic fungus of AFT can grow and reproduce in almost all agricultural products.Maize and peanut are the most vulnerable to AFTs. Fusarium toxins, which have strong cytotoxicity andembryotoxicity, are secondary metabolites of a variety of Fusarium fungus. The contamination rate andlevel of Deoxynivalenol (DON) are among the top of sickle bacteria toxins. Therefore, exploring thecontrol method and technology of mycotoxins, especially AFB1and DON, is becoming a hot spot. Maize,as the first major agricultural products of China, is vulnerable to the two toxins, which will serious threathuman health. The study focuses on the control of toxigenic fungal growth and removing toxins inmaize by essential oils fumigation. And this may provide reference for the application of essential oils ingrain storage to prevent fungal toxins pollution.The research methods and specific results are as following:1. Flat-fumigation method was used to compare eight kinds of essential oils: Litsea cubeba oil,citral, cinnamon oil, eucalyptus oil, eugenol, anise oil, peppermint oil and camphor oil, to find whetherthey can separately inhibit the growth of Aspergillus flavus and it was found that cinnamon oil andeugenol volatile components could effectively inhibit the growth and toxin production of Aspergillusflavus. The inhibitory effect of cinnamon oil was much better than eugenol. When the moisture contentof maize powder was13%, the inhibition rate of cinnamon oil to AFB1produced by Aspergillus flavuscan be as high as98.94%. After inoculated with Aspergillus flavus and cultured for20days, AFB1inmaize powder was1.14μg/kg, which was far below the national standard limit value (≤20μg/kg). Thisresult showed that the essential oils fumigation may be a new way in actual storage applications tocontrol grain mildew.2. Flat-fumigation method was used to compare eight kinds of essential oils: Litsea cubeba oil,citral, cinnamon oil, eucalyptus oil, eugenol, anise oil, peppermint oil and camphor oil, to find whetherthey can separately inhibit the growth of inhibition of Fusarium and found that citral and eugenol canboth effectively inhibit the growth and toxin production of Fusarium graminearum. When the moisturecontent of maize powder was21%, their inhibition rate to DON produced by Fusarium graminearumrespectively were98.33%and95.64%. After inoculated with Fusarium graminearum and cultured for 20days, DON in maize powder were both below the limited range of national standards the (≤1mg/kg).Citral can also effectively inhibit the growth of Fusarium moniliforme.3. Fumigation method was used to compare eight kinds of essential oils: Litsea cubeba oil, citral,cinnamon oil, eucalyptus oil, eugenol, anise oil, peppermint oil and camphor oil, to find whether theirvolatile substances can separately degradate AFB1and found thatcinnamon oil can effectively degradeAFB1in maize powder. We also studied the degradation ability of cinnamon oil to other aflatoxins, andthe results showed that cinnamon oil can degrade aflatoxin AFB1, AFB2, AFG1, AFG2and AFM1, butthe abilities were different. This phenomenon was thought to be caused by the different structure type ofaflatoxins.4. Fumigation method was used to optimize the parameters of using cinnamon oil to degradateAFB1in maize powder. First, single factor experiment was used to determine the main factors whichcan affect cinnamon oil’s degradation rate of AFB1.The results as following: fumigation time,fumigation temperature and the dosage of cinnamon oil. Then orthogonal design experiment was used toanalyze the primary and secondary relationship of factors. The results: the dosage of cinnamon oil>fumigation time> fumigation temperature. The optimum parameter were fumigation time28days,cinnamon oil dosage15mg, and fumigation temperature18°C. And in this condition, the degradationrate of AFB1was64.5%.