Study On Key Technology Of Producing The Flour Of Less Bacterium

China is the largest wheat production and consumption country in theworld,having an average of nearly one hundred million tons of wheat yield.Themicrobial contamination in wheat is common and it is difficult for the traditionalwheat flour processing technology to eliminate it.We can not completely avoid thesecondary pollution in wheat flour when processing.Once the environmentalconditions are suitable,it will cause fever mildew.Since wheat flour can not bewashed and sterilized in large number and even baking can not completely killthermophilic bacteria,it will affect food safety seriously.So wheat processing link isthe key to solve the security problem of wheat flour as well as its products.In orderto ensure food safety,clear requirement of wheat flour microorgaism index has beenproposed by large-scale plantings of food processing enterprises in ourcountry.However,it is difficult to produce the flour of less bacterium using domesticwheat which has high microbial counts and there is no technology currently.Themicrobial contamination in wheat milling process and the quantitative changes ofdifferent kinds of microorganism were analyzed and the results showed that themicrobial pollution comes mainly from raw wheat and tempering process.Thus thekey technology of producing the flour of less bacterium was to reduce the microbialcounts of raw eheat and to control the microbial breeding when tempering.As a kind of high effective and widely used disinfectant,ozone has been widelyused in the food industry and its safety has been recognized by the internationalcommunity.In this research, the raw wheat was exposed to ozone gas in order toreduce the microbial counts of raw wheat and the ozonated water was used totempering. It will offer reference for the flour of less bacterium processing usingdomestic wheat and making microorganism limitation in wheat flour.The results asfollows:1.Ozonization on microbial counts and fatty acid value of wheatAfter ozone treatment,the microbial counts of raw wheat had reduced significantlyand it had good sterilization effect on Escherichia coli and Bacillus cereus. While thehigh ozone concentration and long treatment time made the fatty acid value of wheatincrease quickly and it had bad effects on wheat quality.Further analysis showed thatthe amounts of aerobic bacteria，aerobic bacterial spores, Bacillus cereus，Escherichiacoli，moulds of wheat had very significant correlation and a linear relationship withthe concentration or processing time of gaseous ozone. The ozone treatment concentration and time chose75ppm and15min respectively by the sterilization effect and quality.At this condition the microbial counts of wheat were significantly reduced，but thefatty acid value of wheat did not significantly increased with check experiment.2.Study on producing flour of less bacterium with raw wheat treated by ozoneThe results showed that the concentration and processing time of gaseous ofgaseous ozone and tempering temperature significantly influenced the microbialcounts of end product wheat flour.The optimal conditions of processing based on theorthogonal experiment were as follows:the concentration of ozone gas75ppm,processing time20min,tempering temperature10℃.The amounts of aerobicbacteria,aerobic spores and moulds were470CFU/g，180CFU/g and340CFU/grespectively and the number of Bacillus cereus and Escherichia coli were <10CFU/gin wheat flour producing by the technological conditions and there were no significantdifference of wheat flour quality properties between gaseous ozone treatment groupand control group(P>0.05).3.QuantitativechangesofmicroorganisminwheatflourprocessingwithrawwheattreatedbyozoneAfter ozone treatment,there were various degrees of fall of the microbial counts ofraw wheat and then they had increased when tempering.After milling,the microbialcounts of end products appeared some regularity.The microbial counts of raw wheathad a very significant positive correlation and a linear relationship with that of wheat.4.Study on producing flour of less bacterium using ozonated water to temperingThe results indicated that the amounts of aerobic bacteria,aerobic bacterialspores,Bacillus cereus,Escherichia coli and moulds were significantly reduced inwheat,wheat flour and wheat bran when using the ozonated water to tempering andthe higher the concentration of ozonated water was,the more obvious effect ithad.When using the ozonated water of higher concentration—5.5mg/L totempering,the amounts of aerobic bacteria,aerobic bacterial spores,Bacilluscereus,Escherichia coli and moulds decreased13.4%,17.1%,100%,100%,15.6%respectively. With the5.5mg/L ozonated water to tempering and the temperingtemperature was controlled at the same time,the amounts of aerobic bacteria,aerobicbacterial spores,Bacillus cereus had extremely significant positive correlation withtempering temperature while Escherichia coli was not detected in differenttemperatures. All things considered, the optimal conditions of processing were asfollows: the concentration of ozonated water5.5mg/L, tempering temperature10℃.The amounts of aerobic bacteria,aerobic spores and moulds were310CFU/g， 210CFU/g and230CFU/g respectively and the number of Bacillus cereus andEscherichia coli were <10CFU/g in wheat flour producing by the technologicalconditions and there were no significant difference of wheat flour quality propertiesbetween ozonated tempered group and control group,such as moisture content,fattyacid value and colour.As staple food and the important raw material of industry,wheat flour played a veryvital role in ensuring people,s health and the quality safety of the food and industrialproducts.Studying on the production technology of the flour of less bacterium has thevital practical significance.It can ensure the quality safety of the flour and its productsand people,s health.It can enhance the competitiveness of high-end products andimprove the applicability of domestic wheat as well.