Microwave Sterilization Of Bacillus Cereus From Wheat Flour

Wheat flour is one of the most important food raw materials in China.According to Chinese regulations,Bacillus cereus is used as the reference bacteria for pathogenic bacteria in wheat flour.When Bacillus cereus exceeds the standard,it will produce vomiting toxin and diarrhea-causing toxin in food,causing food safety risks.The contents of Bacillus cereus and other microorganisms in B,M and bran were deter mined,and the distribution of Bacillus cereus and other microorganismsin wheat flour were analyzed.Microwave sterilization technology was used to sterilize wheat flour under different microwave power,sterilization time,moisture content of samples.The content of Bacillus cereus in wheat flour after microwave sterilization was deter mined.The effects of initial moisture content,microwave power and sterilization time on the sterilization effect and quality of wheat flour were researched.Taking the killing rate of microwave sterilization and wheat flour gluten content as evaluation indexes,the better sterilization parameters of microwave sterilization were explored by orthogonal test,and the quality of wheat flour sterilized with better sterilization parameters was verified.The microwave sterilization technology was optimized by intermittent microwave sterilization.Conclusions are as follows:The microbial content was the highest in the bran,followed by the B,and the content was lower in the M.To a large extent,the microbial content was distributed according to the wheat parts,with high microbial content in the epidermis and low in the endosperm.The mold was distributed evenly in wheat flour samples,which was related to the growth and reproduction characteristics of the mold.The growth trend of Bacillus cereus in wheat flour samples was first to increase and then to decrease.The growth trend of Bacillus cereus in the M is special,the growth and reproduction rate is fast and the stable period is long.Low or high moisture content will reduce the killing effect of microwave sterilization.With the increase of microwave power and sterilization time,the bactericidal rate of Bacillus cereus increased gradually.The killing rate was over 99%,under the condition of 700 w microwave power and 7.5 min sterilization time.The longer the time of sterilization by microwave,the higher the microwave power,and the lower the content of Bacillus cereus in the storage process of wheat flour.With the increase of microwave power and sterilization time,the wet gluten content of wheat flour increased first and then decreased.The gelatinization characteristics of wheat flour sterilized by low intensity microwave were different from those of high intensity.Three kinds of better sterilization parameters can be selected according to the orthogonal test.Among them,sample 2(5.5 min-700w-15%)has smaller tensile resistance,the largest elongation,the smallest tensile ratio,and the smallest hardness and stickiness of the dough.The quality of steamed bread made from sample 2(5.5 min-700w-15%)was the best,and the difference in appearance,aspect ratio,specific volume and texture characteristics was similar tounsterilized wheat flour.Intermittent microwave sterilization was used to treat wheat flour,with microwave power of 700 W,sterilization time of 6.5 min,and interval time within 1 min,the sterilization effect is acceptable.With the sterilization time of 7.5 min and the interval time within 1.0 min,the sterilization effect is better.Intermittent microwave sterilization can only control the content of Bacillus cereus at a low level for a long time in the sterilization with a short interval,such as 0.5 min,1.0 min interval.After Intermittent sterilization,the quality change of wheat flour was smaller than that of non-Intermittent sterilization wheat flour samples,such as damaged starch content,gluten content,rheological characteristics,etc.