Survey On Microorganism Contamination Of Flour In The Mainly Wheat Cultivating Area Of China

The microorganism contamination of wheat flour and its milling process in HuangHuaiHai district-the mainly wheat cultivating area of China was studied in this paper. A total of 191 flour samples including some obtained in milling process have been analyzed by counting method, such as: aerobic bacteria, molds and yeasts, coliform bacteria, Bacillus spp, thermophilic microbe, thermophilic aerobic bacterial spores and Bacillus cereus. It can be concluded by the results that:(1) The most frequent (modal) counts of total bacterial in wheat flour are 104 colony forming units/gram(cfu/g), molds and yeasts are 103cfu/g and the coliform bacteria counts are 102cfu/g; The most frequent (modal) counts of Bacillus spp. in wheat flour are about 103cfu/g, the thermophilic aerobic bacterial spores is 102cfu/10g, the positive samples of Bacillus cereus is 94.35%, with a frequent count of 102 cfu/g. The thermophilic microbe counts are between 102～103cfu/g.(2)There relationship between each kind of microorganism in wheat flour is that. The percentage which aerobic bacterial count is ten times higher than the mould and. yeast count is 60.64% in all 188 samples and the 4:3 is the common proportion; The percentage which aerobic bacterial count is two magnitudes higher than the Coliform bacteria count is 48.02% in all 177 compared samples and the 4:2 is the common proportion; The percentage which aerobic bacterial count is one magnitude higher than the Bacillus spp is 57.06% in all 191 samples and 4:3 is the common proportion;The percentage which aerobic bacterial count is one magnitude higher than the thermophilies is 50.79% in all 191 samples and 4:3 is the common proportion.(3) The flour samples which it’s processing enterprise passed the ISO9001 quality certification system have low microorganism quantity; the microorganism quantity of the samples which don’t pass the QS (quality safe) certification system was higher and those passed the QS in the middle. The hygienic index drops with the quantity increase of microorganism and the drops of product quality.(4)The inner machine recontaminate was the mainly factor effect the microorganism quantity of end product in milling process. The rule of microorganism quantity distributing in end product is that, the higher the grade, the lower the microorganism quantity. The mold quantity change not evidence maybe the reason for long growth periods of mold. (6)The result of microbial species identification show that, 7 meso-philes bacillus and 4 thermophiles bacillus isolated from wheat flour and the model strain is Bacillus licheniformis, Bacillus cereus, Bacillus subtilis. 16 mold species in 6 genus was isolated and the most common was Aspergillus sp. and Penicillium sp and detect rate of Aspergillus flavus and Aspergillus niger is high.The results show that the microorganism contamination of wheat flour in China is relatively serious and more attention should be paid on the problem of food security. The source management as well as the flour mill inspection and combination should be the key points in wheat flour microorganism contamination control for the establishment of whole microorganism contamination prevention and control system to limit the latent factors against food security in low level.