| China's traditional fermented sausage production is still in dependence on the natural environment of the extensive production of the state,the fermentation process susceptible to microbial contamination,quality instability,security is difficult to guarantee.With the improvement of consumption level,the quality and safety of fermented sausages are demanded more and more.It is the hotspot to study the production of fermented sausage by screening safe fermentation strains from traditional meat products.In this study,the fermentation of sausage and the content of biogenic amines in different strains were studied by single-bacteria and mixed mushroom fermentation.It provides a theoretical basis for the development and utilization of the fermented strains of excellent meat products.The contents and results are as follows:1.According to the screening criteria of meat products,the screening criteria are the screening indexes,the acid-producing ability and the growth ability of the lactic acid bacteria screening index,the protease activity and the lipase activity of Staphylococcus aureus index,qualitative and quantitative analysis and comparison 5 strains of bacteria producing amines,of which L2 and L4 are not produced histamine,spermidine and spermine,S4 did not produce putrescine,histamine,spermidine and spermine.Therefore,it was preferable that three strains of L2,L4 and S4 were used as safety strains to produce fermented sausages.L2 was Lactobacillus plantarum(LP),L4 was Lactobacillus delbrueckii(LC),S4 was Staphylococcus xylosporin(SX)by physiological and biochemical tests and 16S rDNA sequencing.2.The effects of LP,LC,LP+SX and LC+SX on the physical and chemical quality,free amino acid and flavor of fermented sausage were studied and compared with commercial strain SHA-24(CS)and blank group(CK).The results showed that LP and LC were mixed with SX with 2:1,respectively,and the ability of producing acid was fast and the growth ability was strong.The effect of mixed bacteria on the quality of fermented sausage was significantly higher than that of single and CK(P<0.05).In the process of maturation,inoculation of fermented strains can quickly reduce the pH value of fermented sausages,reduce water activity,improve the color of sausage,increase the content of free amino acids.SPME-GC-MS was used to analyze the flavor substances in the fermented sausage.The esters were the main volatile flavor substances,accounting for 37%-46%of the flavor substances.CK,LP,LP+SX,LC+SX and CS were 583.32?g/kg,664.75 ?g/kg,658.15 ?g/kg,1087.31 ?g/kg,922.15 ?g/kg,976.54 ?g/kg.LP+SX sensory score higher than other groups,comprehensive pH value,Aw value,color,texture,free amino acid,flavor and sensory evaluation and other indicators,indicated that LP+SX could significantly improve the quality of fermented sausage.3.The effects of different strains on the fermentation of sausage microorganisms were studied,the results showed that the lactic acid bacteria were the dominant bacteria in the fermented sausage,and the total number of bacteria,the number of lactic acid bacteria and the number of staphylococci increased first and then decreased.At the end of maturation,the four levels of free amino acids in LP+SX group were the highest,TVB-N value was 18.52 mg/100g,which was significantly lower than that of other treatment groups(P<0.05).The contents of putrescine,cadaverine,tyramine,histamine,spermidine and spermine in fermented sausage were determined by high performance liquid chromatography.The results showed that there was no detectable putrescine,cadaverine,tyramine,histamine,and spermidine in the sausage of each group about 9.50 mg/kg.The biogenic amines in the CK group were the highest,which was more significant than that of the single-bacteria fermented sausage group(P<0.05).Inoculation of LP+SX can inhibit the oxidation of fat in fermented sausages,inhibit the formation of biogenic amines,and improve the safety of sausages. |
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