Study On The Effect Of Bacteriological Reduction And Tempering On Microorganisms And Wheat Flour Quality

In order to improve grinding efficiency,tempering is necessary before wheat is milled.However,in a suitable temperature and humidity environment,microorganisms can easily breed and reproduce,affecting the storage life of flour and flour products.Therefore,it is of great significance to control this process to reduce the microbial content for the production of low bacterial powder.This subject takes Zheng Mai 7698 as the raw material,controls the water quality,temperature and time in the process of tempering,probes into the influence of tempering conditions on the quality of wheat microbe and wheat flour,and optimizes the combination of bacteriostatic tempering conditions.On this basis,it compares the three methods of ozone water,slightly acidic electrolytic water and conventional tempering,and studies the influence of wheat flour and by-product nutritional properties,protein properties,and dough properties.Finally,the effects of three ways of tempering on the quality and storage period of fresh and wet noodles were investigated.The specific results are as follows:（1）Studying the quality of wheat microorganisms and wheat flour after tempering with ozone water,it was found that as the concentration of ozone water increased,the surface microbial content of wheat decreased,with the best killing effect on coliform bacteria;With the increase of tempering temperature,compared with the control group,the microbial content of the treatment group significantly decreased（P<0.05）.The microbial content of the treatment group was the lowest at 45℃,but the fatty acid value increased;As the tempering time increases,the microbial content between the treatment groups increases,and the tempering time is not easy to be too long;The optimization of ozone water antibacterial tempering conditions is as follows:the ozone water mass concentration is 7.8 mg/L,the tempering temperature is 25℃,and the tempering time is 24 h.After ozone water treatment,the total number of bacterial colonies,coliform bacteria,mold and yeast,thermostable bacillus in wheat flour decreased by 67.64%,100%,59.26%,100%.Polyphenol oxidase,lipase,lipoxygenase and peroxidase decreased by 22.60%,19.79%,14.24%,49.14%.The content of DON decreased by 14.13%.It is conducive to the storage of flour.（2）Studies on wheat microorganisms and wheat flour quality after tempering with slightly acidic electrolyzed water showed that with the increase of the concentration of slightly acidic electrolyzed water,the microbial content on the surface of wheat decreased.When the mass concentration is 40 mg/L,the killing effect is achieved on the total number of Escherichia coli and heat-resistant Bacillus subtilis.The reduction of wheat flour D₅₀ and gelatinization parameters,as well as the increase of damaged starch,whiteness,water absorption,dough formation time,and stability time,indicate an improvement in the structural strength of the dough;With the increase of tempering temperature,compared with the control group,the microbial content in the treatment group decreased significantly（P<0.05）,and there was no regular change between the treatment groups;With the increase of tempering time,the microbial content increased,and compared with the control group,the treatment group significantly decreased（P<0.05）.The whiteness,damaged starch,water absorption,formation time,and stability time of wheat flour first increase and then decrease,while the weakening degree increases and the tempering time is not easy to increase;The optimization of SAEW antibacterial tempering conditions is as follows:SAEW mass concentration 50 mg/L,tempering temperature 20℃,tempering time 24 h.After milling under this condition,the total number of bacterial colonies,coliform bacteria,mold and yeast,thermostable bacillus in wheat flour decreased by 65.33%,100%,92.59%,100%.The activities of polyphenol oxidase,lipase and peroxidase decreased by 20.00%,16.42%,50.68%.The content of DON decreased by 34.29%.（3）The effects of three ways of tempering on the quality of wheat flour and its by-products were studied,and it was found that compared with conventional tempering（A）,the content of reducing sugar in wheat flour,wheat flour and wheat bran after treatment with ozone water tempering（B）and slightly acidic electrolytic water tempering（C）increased,the content of polyphenols in wheat flour,wheat flour and wheat bran after treatment B increased,the content of polyphenols in wheat flour,wheat flour and wheat bran after treatment C decreased,and the total amount of amino acids did not change significantly（P>0.05）;After C treatment,the pasting parameters of wheat flour decreased,indicating that its anti-aging properties and thermal stability were improved;After treatment with B and C,the hydrophobic interaction,free sulfhydryl and soluble protein content in the dough decreased,and the disulfide bond increased,which made the dough more resistant to stirring and more flexible;After B and C treatment,the secondary structureα-helix andβ-the sum of folding proportions increased to 66.93%and 70.26%,β-the sum of rotation angle and random curl decreased,and the peak area of SDS extractable protein decreased,indicating that the skeleton of gluten protein was more stable;Under the treatment of B and C,the formation time,elastic modulus（G’）and viscosity modulus（G’’）increased,and the degree of weakening decreased.After the treatment of B,the water absorption,tensile area and extensibility of the dough increased,and the tensile resistance and tensile ratio decreased.Loss angle tangent value tanδchanging,B and C are both smaller than A,indicating that the comprehensive viscoelasticity of the treated dough has been improved to some extent.（4）The effects of three ways of tempering on the quality and storage characteristics of fresh and wet noodles were studied,and it was found that compared with A,the L^*value and water absorption of fresh and wet noodles after B and C treatment increased,the adhesion and stretching distance of B increased,the elasticity,breaking force and stretching distance of C increased,the chewing ability decreased,and the sensory score significantly increased;During storage,the total bacterial count and acidity of B and C decreased,and the L^*value,elasticity,cohesion increased.The storage period was extended to 9 and 10 days.Overall,fresh and wet noodles made after treatment with C have the best storage characteristics.