Isolation,Screening And Application Of Staphylococcus And Lactobacillus From Fermented Meat

Femrented meats aren't only nutritious,but also with speeial fiavor and a long shelf-life,which are popular among consumers and have a good potential for industrialization.But the starter cultuer used for meat fermentation depends on import right now,which seriously hindered the industrialization and scale development of fermented meat products in China.Due to the wide variety of traditional fermented meat products and abundant strains,it is a good resource for the development of excellent meat fermentation agents.In order to obtain staphylococcus and lactic acid bacteria which play a key role in the quality of fermented meat products.According to the screening criteria of meat starter,A total of 21 strains staphylococci and 4 strains lactic acid bacteria were separated from 6 traditional fermented meat products.One strain of lactic acid bacteria C36 were found to be antibacterial.The strain C36 was added to the sausages with 21 strains of Staphylococcus,respectively.It was found that when the staphylococcus SLM64 and lactic acid bacteria C36were used together,the increase of sensory quality of the fermented sausage was most significant and there was no antagonistic effect between the two strains.The 16S rDNA genetic identification:the strain SLM64 and C36 were identified to be Staphylococcus xylosus and Lactobacillus plantarum,respectively based on the result of 16S rDNA.The growth characteristics of the two strains showed that the strain C36 grew rapidly until itreached a stable period after 12 h.In addition,the strain of C36 was fast in producing acid and had wide growth temperature range of 24⁴0°C,and was resistant to NaCl and NaNO₂ reached 5%and 150 mg/kg,respectively.The strain SLM64 reached a stable phase at24 h with good acid resistance.It could grow at a pH of 4,and the tolerance to NaCl and NaNO₂ was higher than that of C36.It explore the optimal fermentation process for strains C36 and SLM64 in fermented sausages by single factor and L₉ orthogonal test.The results of single factor showed that the optimal fermentation time was 36 h,the optimal fermentation temperature was 30°C,and the optimal inoculation ratio was C36:SLM64=1:2.The best optimization was obtained by L₉orthogonal test,which demonstrated the optimal fermentation time is 36 h,the optimal fermentation temperature is 30°C,and the optimal inoculation ratio is C36:SLM64=1:3.Under this condition,the fermented sausage showed a moderate pH value?pH 5.1?and high sensory quality.The two strains were mixed and added to the fermented sausage,with the natural fermentation and the single-strain fermentation used as controls.The results showed that the evaporation rate of water in C36:SLM64 group and the single-fermentation C36 group was faster.At the end of the ripening,the water evaporation rate were 36.54%and 35.11%,respectively,which was significantly higher than that of the SLM64 and CK groups?P<0.05?.The pH value of the C36:SLM64 group and C36 group of sausages decreased to a minimum of 5.1 at the end of fermentation?1.5 d?,and the amount of enterobacteriaceae in the two groups of sausages was significantly lower than that of SLM64 and CK groups?P<0.05?.At the end of the chilled storage,the enterobacteriaceae in the two groups of sausages were hardly deteced,which indicated that Lactobacillus plantarum C36 had a significant effect on reducing the moisture content of sausages,lowering the pH value of sausages and inhibiting the growth of enterobacteriaceae in sausages.By measuring the color difference of sausages,L value and the a value of C36:SLM64group and SLM64 group reached the maximum at 1.5 d and 4 d,respectively,which were about 55.25 and 18.4,respectively.The difference between the two groups was not significant?P>0.05?,but significant higher than the other two groups?P<0.05?;the b value of C36:SLM64 group decreased to the minimum value of 4.18 on the 4th day,which was significantly lower than the other three groups?P<0.05?.It could be concluded that composite fermentation were benefical to the color formation and stability of sausages.By measuring the content of nitrite residues,TBA and TVB-N in sausages,the content of nitrite in the added starter group gradually decreased,which was significantly lower than that in the CK group?P<0.05?.At the end of the refrigeration,The nitrate content of C36:SLM64 group was 6.83 mg/kg,which was significantly lower than the national standard value of 30 mg/kg.The content of TBA and TVB-N of C36:SLM64 group were 0.74 mg/100g and 8.40 mg/100g,respectively,significantly lower than the other three groups,which indicated that the compound starter is beneficial for reducing the nitrite content and inhibiting lipid oxidation and protein spoilage in sausage.