Influencing Factors Of Shelf Life For Baigan And Control Measures

The bean products play an important role in nutrition balance to human, especially in fully intake of protein. However, they are easy to be contaminated by microorganism due to the rich nutrition and high moisture content, which result in the very short shelf life. Through studying all the main factors that affect the shelf life of products, control measures are proposed to extend the shelf life of soybean products.The study start with a bean product named Baigan, which is a kind of white dried bean curd without fermented, mainly on its present shelf life and influencing factors. According to GB standard (GB/T 22106-2008) of unfermented bean product and the reality in circulation, key indexes such as sensory assess, weight loss ratio and pH were selected to review the influence of package pattern, initial microorganism population, storage temperature. The results show that initial microorganism population, package pattern and storage temperature in circulation significantly affect the shelf life. The shelf life could be extended, if the initial microorganism population was decreased, proper package used and storage temperature controlled less than 4℃. Among the three influencing factors, initial population is proved to be the key factor. Thus, tracking research in Baigan production indicates that cleanness of raw material and secondary contamination are the main reasons of initial population increasing, package pattern is the key measure to prevent secondary contamination in circulation, and temperature controlling is an important step to inhibit the growth of microorganisms on Baigan.Considering microorganisms are the key factor affecting the shelf life of Baigan, after colony observation, separation, purification and identification, the results show that Bacillus subtilis and Enterococcus faecium are main putrefying bacteria. Through traceability study on production procedure of Baigan, secondary contamination is believed to be the main reason of putrefying bacteria contamination. The first growth model at 5℃,10℃,15℃,20℃are found using curve fitting of microorganism prediction model, and the second predictive model is established by relationship research between temperature and growth velocity. The prediction result demonstrates that production temperature for product should be under 15℃, otherwise, putrefying bacteria cling on Baigan would reproduce a lot, and shorten shelf life.Finally, HACCP principle and the result of predictive microbiology model are combined to confirm the CCPs which should be controlled in production. These CCPs are initial microorganism population of raw material, time of boiling bean milk, secondary contamination, sterilizing time and storage temperature. CL of each CCP is also confirmed to prevent secondary contamination, decrease initial population of Baigan and prolong its shelf life.