| Background:In the Guangdong area,wet rice noodles are a kind of traditional snacks,which are very popular among Guangdong residents.Because of the high water content,rich nutrients,and long-term high temperature storage conditions during transportation and sales,these reasons provide necessary conditions for microbial growth and spoilage of wet rice noodles.In recent years,more and more cases of food poisoning of wet rice noodles have been reported in various places,and the microbial contamination of wet rice noodles has gradually gained attention.Bacillus cereus is a common and less toxic bacteria in wet rice noodles.Controlling its content in wet rice noodles is important for reducing the microbial contamination of wet rice noodles.Therefore,it is beneficial to improve the food safety level of wet rice noodles by studying the contamination of Bacillus cereus.Objective:1.To understand the hygienic condition of wet rice noodle enterprises in Guangzhou and provide reference for the formulation of hygienic standards or production standards for wet rice noodles..2.To understand the contamination rate and pollution level of Bacillus cereus in the production process,analyze the pollution source of Bacillus cereus in wet rice noodles,and determine the critical control points..3.A quantitative risk assessment model of Bacillus cereus contamination in the transportation of wet rice noodles was established to quantitatively analyze the exposure risk of Bacillus cereus in wet rice noodles sold in the market.Methods:In this study,from March 2020 to July 2020,11 wet rice noodle enterprises with production licenses were selected from the target area of Guangzhou,considering the sales range and total production.Investigating the enterprise hygiene situation of wet rice noodles includes production process,enterprise situation,production process,infrastructure equipment,management system and so on.Samples of Bacillus cereus testing were collected from all stages of the production and processing of wet rice noodles,including 33 raw material rice,33 starches,33 rice milk,33 wet rice noodles;240 pieces of equipment surface samples were from raw material processing room,maturing and forming room,finished product packaging room and transportation workshop,besides 44 air samples.The data was inputted by Epidata3.0 software,and SPSS19.0 software was used for statistical data.The measurement data were described by mean and standard deviation.One-way ANOVA or rank sum test was used for comparison between groups,and Q test was used for pair comparison between groups.Enumeration data were expressed as rate,chi-square test and Fisher’s exact probability test were used for classification variables,and Pearson correlation analysis or Spearman correlation analysis were used for correlation analysis,with the test level α=0.05.Results:1.The results of hygienic investigation of wet rice noodle enterprises showed that 36% of the enterprises had cracks or uneven floor,82% of the enterprises did not keep a proper distance from the walls and floors,45% of the enterprises were not equipped with adequate ventilation facilities,36% of the enterprises had poor drainage and stagnant water,36% of the enterprises had incomplete cleaning pipes,100% of the enterprises did not have air,temperature and humidity control equipment,and 55% of the enterprises did not record the cleaning and disinfection of the equipment in time.36% of the enterprises did not establish personal training files,45%of the enterprises did not carry out training effectiveness evaluation,45% of the enterprises did not have laboratory and qualification inspection personnel,36% of the enterprises did not keep product sample records,73% of the enterprises had no product batch records or unreasonable production batch records,no product withdrawal or handling records,no summary reports,and 45% of the enterprises had irregular production labels.2.The Bacillus cereus testing was positive in the air in the raw material warehouse,raw material processing room,curing and molding room,and finished product packaging room,and the average number of colonies was less than 1CFU/dish.There was no significant difference in the number of Bacillus cereus in the air in each workshop(H=3.173,P=0.366>0.05),and the total number of air colonies in each workshop had no significant difference(H=5.074,P=0.166>0.05).At the same time,there was no significant correlation between the total number of colonies in the air in the raw material warehouse,raw material processing room,curing room,and finished product packaging room and the number of Bacillus cereus(P> 0.05).3.The Bacillus cereus testing was positive on the surface of each equipment.The overall detection rate of Bacillus cereus was 42.50%,and the detection rate of Bacillus cereus in the raw material processing room(growing area)was 56.79%(46/81);the detection rate of the curing and molding room and the finished product packaging room(both the ripening zone)were 33.68%(32/95)and 22.22%(6/27)respectively;the detection rate of the surface of the loading and transportation tool was 51.43%(18/35).The detection rate of Bacillus cereus between the three workshops and the loading and transportation tools was significant differences(χ2=19.81,P<0.05).The binomial distribution test showed that the detection rate inside the mixing tank,cutter and transport car was significantly higher than the overall detection rate of 42.5%,while the detection rate of conveyor belt,fan and weighing was significantly lower than the overall detection rate of 42.5%.There was significant difference in the detection rate of Bacillus cereus among the four workshops(χ2 = 16.577 P < 0.05).The results of pairwise comparison among multiple groups showed that there was a significant difference in the detection rate of Bacillus cereus among raw material treatment,ripening molding and finished product packaging(P< 0.05).There was no significant difference in the detection rate of Bacillus cereus between the transportation workshop and the other three workshops(P > 0.05)..4.The detection rate of Bacillus cereus in rice was 93.94%(31/33),and the detection amount was 1.93±0.52 log CFU/g;the detection rate of starch was 30.30%(10/33),and the detection amount was 1.42±0.35 log CFU/g;the detection rate of rice milk is 66.67%(22/33),the detection amount is 2.95±1.15 log CFU/g;the detection rate of the finished product is 51.50%(17/16)the detection amount is 2.77 ±1.27 log CFU/g.There was no significant difference in the detected amount of Bacillus cereus between rice and starch(P>0.05).There was no significant difference in the detected amount of Bacillus cereus between rice milk and the finished product(P>0.05).There was significant difference in the detection of Bacillus cereus between rice and rice milk and finished products(P < 0.05),and there was significant difference between starch and rice milk and finished products(P < 0.05).5.The 90% range of the predicted contamination concentration of Bacillus cereus in wet rice noodles sold in the market is 1.68 log CFU/g-5.28 log CFU/g,the average concentration is 3.44 log CFU/g,and the probability of exceeding 5.0 log CFU/g is 14.7%.Conclusions:1.Wet rice noodle companies in Guangzhou have different levels of hygiene problems such as regional planning,infrastructure,and management systems.2.Bacillus cereus in wet rice noodles is mainly comes from raw rice.There is a significant difference in the detection amount of Bacillus cereus in rice milk and rice.The high-temperature maturation process cannot effectively kill Bacillus cereus.3.The surface of equipment such as mixing tanks,cutters,and transport carriages are the main pollution source of cross-contamination of Bacillus cereus.4.The contamination risk of Bacillus cereus in wet rice noodles sold in Guangzhou was high,and 14.7% of the wet rice noodles on the market exceeded the standard limit. |
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