Research On The Sampling Schemes Of Main Grain Mycotoxins For Whole Supply Chain

Mycotoxins contamination is one of the most serious contamination in food safety.Nowadays,there is no approved and standardized sampling scheme of grain mycotoxin in the world.Designing a scientific,reasonable sampling scheme of grain mycotoxin is an important method to control grain mycotoxin contamination in whole-supply-chain.In the paper,two typical mycotoxins,i.e.deoxynivalenol(DON)in wheat and aflatoxin B₁(AFB₁)in rice,were used to design the sampling schemes of the four stages in whole-supply-chain,field harvest,storage,processing and shelf life,to provide scientific basis of mycotoxin contamination of wheat and rice.The grain samples of rice and wheat planted in the fields,where located in the plain of Henan and Hebei province with continental monsoon climate,were selected to design the sampling scheme,comprehensively considering the factors,such as temperature,humidity,wind direction,and other conditions of the weather before harvest a week.The grain samples from different locations in the fields were sampled,and the mycotoxin contents of the samples were detected so as to analyze and determine the scientificity of the sampling scheme.The results showed that the mycotoxin contents of the samples from different locations in fields were significantly different in locations and wind directions.There were different mycotoxins contents of the samples in the rice field(P<0.01)and wheat field(P<0.05),located in the peripheral(P area),middle(M area)and other(O area).Furthermore,the DON mycotoxins contents of samples located in upwind direction were significantly higher than that of the samples in other wind direction.Ninety six percent of DON mycotoxins in the wheat samples can be removed through the shelling process.We found that the AFB₁contents of rice samples lodging in the field were not obviously affected by lodging.We suggested the sampling scheme of grain samples planted in the field before harvest as follows:Three areas would be divided in 15 ha field planted grain,i.e.peripheral(P area)where located the 10 m perimeter of the field as P zone,middle(M area)where located 100–150 m away from the edge of the field as M zone,and other(O area)to monitor the mycotoxin contents of grain samples contaminated,The density of sampling in P,M and O areas should be controlled at 75,50 and above 100 m per sample,separately,and the density of sampling in the upwind of P area should be increased,the sampling shape of M area is like Z word.The sampling scheme would be comprehensively measured the pollution mycotoxins of grain samples planted in the field before harvest.In order to design a scientific sampling scheme for mycotoxin pollution of grain samples during storage,we simulated the conditions of insect damage and ventilation during grain storage,and looked for the characteristics of mycotoxin occurrence in grain storage.We tested the water contents,mycotoxins contents and their relationship between them with different numbers and locations of Sitophilus zeamais after infected insect pests at three doses(high,medium and low)of insects in storage samples of wheat and rice.Then,the relationship between high moisture content and mycotoxin distribution in wheat was investigated under simulated ventilation condition in the storage.The results showed that the density of Sitophilus zeamais could not significantly increase water contents in the wheat samples,but wheat water contents were significantly correlated with DON contents(P<0.01).There was significant correlations between the density of Sitophilus zeamais and water contents of rice samples,and between water content and AFB₁contents of rice samples(P<0.05).Therefore,the density of Sitophilus zeamais had a significant correlation with the contents of DON in wheat samples and AFB₁in rice samples;During the ventilation process in storage,the moisture contents of wheat decreased and DON contents increased with the extension of ventilation time.We proposed the sampling scheme of storage period:the contaminations of DON in wheat samples and AFB₁in rice samples can be inferred according to the conditions of the occurrence Sitophilus zeamais.The main areas of the occurrence Sitophilus zeamais are 10 cm below the surface of grain pile,where are also the key sampling points contaminations of DON in wheat samples and AFB1 in rice samples.The easy mildew points avoiding the ventilation pathway are the monitoring points of mycotoxin contaminations of wheat samples,these points should be paid attention to sample.During the phases of grain processing and shelf life,the mycotoxin contents of wheat flour and rice sampling in different processing steps and shelf times were detected.The results indicated that DON contents in wheat bran and AFB₁contents in rice bran,were the highest in the processing technology,which showed a decreasing trend from outside to inside in the grain.Therefore,in the processing of wheat and rice,the outer bran shelled from the grain is the key points to monitor mycotoxin contamination of grain.DON contents in the wheat flour is highest after produced about 4 months,AFB₁content in rice significantly increased after produced 7 months.Therefore,for monitoring the mycotoxin contamination of shelf life of wheat flour and rice,the times with significantly increasing mycotoxin contents should be taken as the key points to control the quality of food.This is the first time to systematically research the key points monitoring mycotoxin pollution of wheat and rice in the whole supply chain,and suggest the corresponding sampling schemes,which produced a large number of detailed and scientific data to ensure food safety.