Isolation Of Primary Microorganism From Northern Natural Fermented Dry Sausage And The Studies Of Zymotechnique

The natural fermented dry sausage in North China is extroordinary popularfor its unique flavor and nutrition. As is the main material, raw meat should betrimmed, minced and mixed with accessories subjected for casing, fermentation,and drying. The article initiated with the microflora of dry sausage in NorthChina. Further more, the primary microorganisms were isolated and used asstarter culture for product validation by sausage fermentation. The final purposeof the article is provide the theoretical foundation for starter culture exploiting.Plate count and PCR-DGGE has been used for microflora analysis for threekinds of natural fermented sausage in North China. The results showed that theLAB (lactic acid bacteria), Staphylococcus and Bacillus are the primarymicroorganism. The results of plate count indicated the microbial growth reachedits peak in the fifth day of fermentation. The number of LAB and Bacillus wasmore than10~7cfu/g, greater than the number of Staphylococcus and Micrococcuswhich is10~6cfu/g.The LAB, Staphylococcus, Micrococcus, Bacillus in three kinds of naturalfermented dry sausage was isolated by three medium MRS, MSA and MYP. Theresults of isolation indicated12strains conformed to LAB,11strains lined withthe characteristic of Staphylococcus and Micrococcus,12strains of Bacillus. Thestrain screening was carried on by the strain tolerance of nitrite, salt,low-temperature, acid resistance and the fermenting property incluedingproteolysis capacity, lipolysis, nitrite reduction ability and acid productioncapacity. The results of these experiments showed33strains of the35isolatedcould tolerate nitrite of150mg/kg, that30strains could withstand the lowtemperatur of15℃, all of the strains can grow in the environment of pH=5.0,12strains possessed proteolysis capacity,9strains could hydrolyzed fat. The LABstrains LA2and LC3could lower the pH of broth respectively to4.39and3.94form7.0. The acid production capacity was significantly higher than other strains.Cocci SC3which possessed nitrate reductase capacity4.1U/ml was the best of11strains.To considering the characteristic of strains, LA2, LB2, LC3, SA1, SA2, SC3,BA1, BA2, BC3was selected for fermentation experiments. The biologicalcharacteristics of9strains has been tested. The optimum growth temperature ofthese strains was30~37℃, optimum growth initial pH of LAB and cocci is from7to7.5, Bacillus suitable initial pH is6. The9strains entered logarithmic phasein2~4h,10~~15h entered a stable period. The protease and lipse producing timeand yield of the9strain is differences, SA2, in60h, protease could be up to 85U/ml, was significantly higher than other strains. The maximum lipase ac tivityof SA2and BA1were2.69U/L(60h) and2.89U/L which significantly higher thanthe other strains.The identification results of16SrDNA showed that LA2, LB2, LC3, SA1,SA2, SC3, BA1, BA3, BC3respectively was Weissella thailandensis,Lactobacillus sakei, Lactobacillus sp.,Staphylococcus saprophyticus,Staphylococcus xylosus, Kocuria rosea, Bacillus pumilus, Bacillus safensis,Viridibacillus arvi.Single strains and composited strains have been used for fermentedexperiment. The prepare of dry sausage refered the formulation of Zheng Yanloudry sausage. The conflict experiment results that the LAB may inhibit the otherstrains by acid-production. The are weak conflict between Cocci and BacillusSingle strains fermented experiment indicated the red value of inoculation SA1,SA2, SC3, was significantly higher vaccination SA2, SC3, and the hardness ofthe group was significantly higher. The composited strains fermentedexperiments showed all the batch could quickly lower the pH. The TPA analysisshowed that the hardness of the groups were higher than control, the hardness ofbatch1(LA2+SA2+BA1) and batch6(LC3+SA2+SC3+BA1) was significantlyhigher than the other combinations, the results of color analysis showed that thered value of batch1and batch2(LC3+SA2+BA1) was higher. The results of thesensory evaluation showed that group1and group6had high acceptance, wasinitially identified as a good combination. We carried out inoculum sizeoptimization experiments of excellent combination, the results of theoptimization showed that when the inoculation size of group1was1%, theacceptance was higher. The group6got a higher accept degree by inoculationsize10~%.On the basis of microflora analysis, the primary microorganism has beenisolated in this article. Further more,9excellent strains has been selected by theresearch of sausage-environment tolerance ability and fermented characteristics.Be based on the biological and fermented experiment, the dry sausage producthas been validated by pure strain inoculation fermentation. Two excellentcomposited strains (LA2+SA2+SC3) and (LC3+SA2SC3+BA1) has beenselected by fermentation experiments of single strains and composited strains,which has been lie the theoretical and practical foundation for the exploiting ofmeat starter culture.