Quantitative Assessment Of Risk Control Factorsfor Bacillus Cereus Contamination In Wet Rice Products And Starch Products

Background and ObjectiveSince 2018,a number of cases of bongkrekic acid(BKA)poisoning caused by eating wet rice products and starch products in Guangdong Province,which has aroused high attention from market supervision authorities and the people.Through the previous monitoring of microbial contamination in wet rice products and starch products that the detection rate of B.cereus was high,which was related to its characteristics of producing high-resistant buds,difficult to inactivate biofilms,and easy to accumulate in rice.Moreover,there is no obvious change in sensory properties of contaminated foods,but enterotoxin or vomitoxin have been produced,resulting in poisoning after eating.Therefore,B.cereus was chosen as the representative pathogen bacteria in the study of microbial contamination in wet rice products and starch products.Previous monitoring results found that the detection rate of B.cereus in raw materials(including rice,crushed rice and starch),factory and marketing wet rice products and starch products were 85%(34/40),50%(16/32)and 43.17%(60/139),the contamination concentrations were 10～103 CFU/g,10～4.97×104CFU/g and 10～2.10×106CFU/g,respectively,indicating that the current production process could not inactivate B.cereus.Temperature is an important factor affecting the growth and reproduction of microorganisms.Several reported cases of BKA in wet rice products and starch products were all related to the food storage time after the factory exceeded the shelf life.Therefore,this study hypothesized that the marketing to before consumption was the key control phase,and the corresponding temperature and time were the key risk factors.In order to verify the above hypotheses,this study was carried out.MethodsFrom July 2021 to June 2022,5 representative manufacturers were selected combining with the distribution,production process and product type of wet rice products and starch products,and collected food and environmental samples corresponding to each phase from raw material to marketing.The quantitative and qualitative detection of B.cereus was carried out respectively,the corresponding time,temperature and pollutin status data data of wet rice products and starch products from production to consumption each phase were recorded.The consumption questionnaire of wet rice products and starch products was designed to understand the consumption level.The@Risk7.5 software was used to construct the evaluation model of B.cereus in wet rice products and starch productsfrom raw material to consumption,and the simulation analysis was conducted.Results1.A total of 507 samples were collected,and the overall detection rate of B.cereus was 35.70%(181/507).The dection rate of B.cereus in food samples was 42.86%(117/273),and the detection rate of B.cereus in environmental samples was 27.35%(64/234).There was no statistical significance in the detection rate of B.cereus between food samples and environmental samples(P=0.054>0.05).2.Wet rice products and starch products is widely consumed,and there is no absolute high frequence consumer population.The average consumption of the consumer group was 190.40 g/times,the highest was 600 g/time,and the standard deviation was 81.53 g/time.3.Model validation results of each phase:R2 was all≥0.96,indicating that the model could reflect and predict the actual situation of Bacillus cereus contamination in wet rice products and starch products.4.After superposition analysis of the model predicted value and the actual dection value of each phase,it was found that only the marketing phase had samples excedding the risk threshold(5 log CFU/g),and the probability was 0.7%.The predicted probability of excedding the threshold before consumption was 40.90%.Combined with consumption,the prediced probability of excedding the exposure threshold was 35.50%.The results of sensitivity analysis showed that T5 and t5 had the greatest influence on the final results,and the correlation coefficient(r)values were 0.49 and 0.43,respectively.ConclusionThe main conclusions of this study are as follows:(1)The contamination of B.cereus in wet rice products and starch products is relatively serious,and the consumer population is wide.(2)The quantitative risk assessment model could reflect the actual situation of B.cereus in wet rice products and starch products.(3)The phase from marketing to consumption was the key control microbial contamination of these foods,and the storage temperature was the key influencing factor,followed by the storage time.(4)The contamination of microorganisms in raw materials cannot be ignored.