Microbial Flora Analysis And Quality Control Of Frozen Prepared Flour Products

Frozen prepared flour products are popular because of their convenient and nutritious.As the temperature was cold,the growth of microbes were restrained,but there were still some microbes could grow and lead to food spoilage,and evenwere harmful to human health.In this paper,noodles,bread dough and steamed dough which were widely consumed were selected as research objects.The compose of microorganisms was investigated in three samples which were kept at 4 ? and 18 ?.Microorganisms in three samples were isolated and analyzed by traditional methods and molecular biology methods.Then the HACCP system was used to control microbes in the production of cold noodles.The main results were as follows:(1)With storage time increasing at 4 ?,the moisture content of noodles decreased,the acidity increased firstly and decreased subsequently.The total number of microbes increased and the bacteria were the main microbial flora of noodles.The moisture content and acidity in the bread dough and steamed dough reduced after rising first.The total number of microbes in two kinds of dough decreased,and the yeast was the main microbial flora.With storage time increasing at-18 ?,the microbes of the three kinds of flour products were reduced as a whole.Bacteria and yeast were the main microbial flora in frozen noodles while yeast was the main microbial flora in frozen bread dough and steamed dough.(2)There were 67 strains of bacteria were isolated and identified as 10 genera from noodles,bread dough and steamed dough by 16 S rRNA sequence analysis.Staphylococcussp.was the dominant species which was isolated 22 strains(32.84%).Bacillus sp.was isolated 12 strains(17.91%).Pantoea sp.was isolated 11 strains(16.42%).Pseudomonassp.was isolated 10 strains(14.93%).Enterobacter sp.and Kocuria sp.was isolated 3 strains(4.48%).And 3 yeast species were isolated from three samples and analyzed by 26 Sr DNA D1/D2 domain sequence analysis,including Saccharomycescerevisiae,Rhodotorula sp.and Pichia anomala.In addition,there were 18 strains of molds in noodles,including 8 strains of Penicillium,7 strains of Aspergillus.(3)The microorganism of three flour products were different under frozen and refrigerated conditions.The common microorganisms were staphylococcus sp.,bacillus sp.,Pantoea sp.and Pseudomonas sp.under frozen and refrigerated conditions.The staphylococcus sp.was the dominant spoilage bacteria whether 4 ? or-18 ?.Serratia rubidaea was only isolated at-18 ?.The bacteria only isolated at 4 ? were Paenibacillus sp.,Enterobacter sp.,Kocuria sp.and so on.And 10 bacteria species,3 yeasts and 5 molds were detected from noodles.5bacteria species and 1 yeast were isolated from steamed dough while 3 bacteria species and 1 yeast were isolated from bread dough.(4)By taking cold noodles production and processing course as research objects,quantitatively detected the pollution of microorganism in materials and equipment,analyzed possible biological hazards and confirmed three critical control points: acceptance of raw materials,knead dough and product storage.HACCP plans were established and used in the cold noodles production processes.The biological hazards and risks of cold noodles were reduced.