Characterization And Application Of Micrococci And Staphylococci Isolated From Fermented Sausages As Starter Cultures

The aims of this study are to isolated staphylococci and micrococci from traditional sausages and to determine the metabolic and probiotic properties of selected Staphylococcus xylosus, in order to select potential starter cultures for fermented sausages. And employ the mixed starters combined with Lactobacillus in the manufacture of fermented sausages, in order to evaluate the effect of the starter cultures on the physico-chemical, microbiological and sensory properties of typical fermented sausages. The main results and conclusion are as follows:1. One hundred and thirty-eight strains isolated during the ripening of a traditional fermented sausage were characterized. Fifty-eight isolated belonged to Micrococcus,with thirty-eight strains(sixty-five point five percent of Micrococcus)belonged to Micrococcus kristinae. Eighty strains belonged to Staphylococcus species, and senventy-three strains(ninty-one percent of Staphylococci)were coagulase- negative and nuclease-negative, and in them there are sixty strains belonged to Staphylococcus xylosus. All of the Micrococcus have pigment, did not apt for using as starters. Starter cultures main separeted from sixty strains of s.xylosus.2. In order to select strains apt for used in fermented sausages, screening first passed technological properties, for example: nitrate reductase. And second passed detection of biogenic amine production, acetoin production, assessment of proteolytic activity and lipolytic activity. At last, from sixty strains of s. xylosus, we isolated four strains. 3. Studyed probiotic of the four strains. We found that they can resistant to strong acidic environment and higher concentrations of bile salt, and two strains C1S23 and C3R10 have bacteriocin. Antibiosis test between lactic bacteria and s. xylosus showed that: s.xylosus C1S23 and C3R10 and LAB11 had no antibiosis.4. The strains of s.xylosus C1S23 and C3R10 were also tested for growth ability at different temperatures, pH and NaCl and nitrite concentrations. The results showed that they were suitable to make starter cultures.5. Two starters formulation were developed combining the proteolytic but not lipolytic s.xylosus C1S23 with the Lactic Acid Bacteria 11 (starter S1) and the s.xylosus C3R10 with the same strain of LAB 11 (starter S2). We employed them in the manufacture of fermented sausages, in order to evaluate the effect of the starters on physico-chemical, microbiological and sensory properties of fermented sausages.6. In all the samples LAB dominated the microflora from the beginning of the fermentation and ripening; Growth of Micrococcaceae in contral sample was inhibited, appeared to be significantly affected by acidification or by the environment of sausage. And the growth of Micrococcaceae in samples with starter S1 and S2 was also inhibited, but because of the great inoculation volume, the growth was basically increased slowly; Samples S1 and S2 showed a reduction tide in Enterobacteriaceae over the same period of time.7. pH value of sample S1 and S2 was significantly lower than the control, after three days reaching the lowest level, and later there was a gradual increased. Inoculated with starter cultures had no effect on the water activity and ash, and made the content of NPN increased. Adding of starter cultures had significantly influenced in Texture. It was significantly increased in hardness, Chewiness and gumminess compared with the control sample. Both S1 and S2 exhibited significant increases in Lightness and redness compared with the control sample. From sensory analysis, it was seen that both starter cultures can be suitable to be used in fermented sausages.