Study On The Change Of Colony And Mold Distribution In The Wheat Flour Production Line And The Influence Factors

With the increasing emphasis on food safety,large multinational and domestic food companies have set specifications for the microbial content of flour,which is new emergence to the milling industry since there was no such specifications in national standards in China.Therefore,controlling the microbes in wheat flours became a new topic for the flour milling industry.The objective of this project was to determine the key points of controlling colonies,mold/yeast in wheat flour through investigating their distribution in the wheat milling process.The stocks contamination from different equipment was studied to evaluate the stock cross-contaminations from varied streams.This project also investigated the effect of using chlorine dioxide?ClO₂?during the wheat conditioning process on the colonies,mold/yeast on the wheat surface and in wheat flour.The results indicated that wheat clean could effectively reduce the number of microorganism,and wheat cleaning worked better in the first clean stage?before wheat conditioning?than the second clean stage?after wheat conditioning?toward microorganism control.The first wheat cleaning stage plays a significant role on decreasing the colonies on wheat surface;therefore effective application of such clean equipment should be ensured.Wheat conditioning should be considered as the key control point since it resulted in significant growth in colonies number.The stocks harbored in the equipment contain high level of microorganism and are risks for wheat flour-based foods.The results also showed that spraying water with 200 ppm of chlorine dioxide to wheat before it goes to the cleaned bin can significantly decrease the colonies numbers.However,the mold/yeast numbers did not show significant change in response to the usage of chlorine dioxide.Colonies and mold/yeast numbers changed in flour,bran,and red dog?low grade flour?with the irregular trend.Data also revealed that stocks harbored in milling machinery and spouting were seriously contaminated.The following suggestions were proposed based on the research results.1)Do regular equipment inside-cleaning to control cross-contamination.2)Shorten the wheat conditioning time under the premise that it meets the subsequently processing requirement.3)Increase the air volume for aspiration under the premises of meeting the processing and energy consumption requirements of milling.4)Control the microbes level in raw wheat.