Preparation Of Functional Strain Starter And Its Effect On Sausage Quality

Fermented sausages are favored by consumers because of their unique flavor and high nutritional value.However,most of them use natural fermentation,which has the disadvantages of long production cycle,high cost,and strong dependence on the natural environment,resulting in large differences in the flavor of fermented sausages and difficulty in controlling quality stability.Excessive fat and protein oxidation during the processing and storage of fermented sausages can easily cause quality deterioration,and functional strain starters have important research significance for improving the flavor and quality of sausages.Staphylococcus saprophyticus CGMCC 3475(Ss)has high protease activity and can degrade proteins in sausages to produce free amino acids.Lactobacillus plantarum CGMCC 18217(Lp10)has excellent branched chain amino acid transaminase activity,which can decompose branched chain amino acids to produce flavor precursors.Lactobacillus plantarum NJAU-01(LpN)has high antioxidant activity,which can inhibit protein and lipid oxidation and improve the quality of sausage.In this paper,the functional strains Lp10,LpN and Ss isolated in the early stage of the laboratory were used as the research objects.Firstly,different combinations of starters were set up to study the effect on the quality of fermented sausages and determine the best combination of starters.Then the best combination of compound starter was prepared into freeze-dried powder and applied to fermented sausage,and compared with commercial starter.Finally,the effect of exogenous leucine on the quality and flavor of fermented sausage was studied by adding leucine and compound starter culture.The results of this study can provide theoretical guidance for the improvement of the flavor and quality of fermented sausages,and provide technical support for the development and utilization of meat starter cultures.The main research contents and results are as follows:1.Effects of compound functional strains on antioxidant properties and flavor of fermented sausage.Lp10,LpN and Ss had no antagonistic effect on each other and could be used in the production of fermented sausage.The control group CK without starter culture and different combinations of starter culture treatment groups Lp10,Lp10+Ss(1:1)and Lp10+LpN+Ss(1:1:1)were set up to make fermented sausages and determine physical and chemical indicators,protein degradation and oxidation indicators,volatile flavor substances and sensory evaluation.The results showed that the color,texture,total sulfhydryl group and surface hydrophobicity of Lp10+ LpN+Ss in the compound treatment group were significantly better than those in other treatment groups(P<0.05).A total of 43 volatile flavor substances were detected,and the content of flavor substances was also significantly higher than that of other treatment groups(P<0.05),and the sensory evaluation score was higher.The above results showed that the combination of Lp10,LpN and Ss could improve the quality and flavor of fermented sausage and reduce the degree of protein oxidation.The treatment group Lp10+LpN+Ss could be used as a compound starter for fermented sausage.2.Application of compound freeze-dried powder in fermented sausage.Lp 10,LpN and Ss were vacuum freeze-dried,and then the number of viable bacteria after freezedrying was measured.It was found that the number of viable bacteria reached 109 CFU/mL,and the survival rate reached more than 70%.The prepared compound freezedried powder starter was applied to fermented sausages,and the quality of fermented sausages inoculated with liquid starter and commercial starter was compared.It was found that there was no significant difference in the total number of colonies,lactic acid bacteria and Staphylococcus,pH,Aw,texture and color between the freeze-dried powder and liquid starter treatment groups(P>0.05).The total sulfhydryl content,carbonyl content and TBARS value of freeze-dried powder were not significantly different from those of liquid starter(P>0.05),but significantly better than those of commercial starter(P<0.05).There was no significant difference in the content of volatile flavor substances and the overall sensory score between the two treatment groups(P>0.05).In summary,the prepared freeze-dried bacterial powder achieves the fermentation effect of liquid starter,and is superior to commercial starter.It can be used as a direct-vat set starter in the production of fermented sausage.3.Effect of leucine on quality and flavor of fermented sausage.Exogenous 3 mmol/kg leucine was added to the fermented sausage,and combined with no inoculation of starter,inoculation of liquid starter and inoculation of freeze-dried bacterial powder.The results showed that there was no significant difference in color and texture between the treatment group with exogenous leucine and the treatment group without leucine(P>0.05).The fermented sausage with exogenous leucine produced branched-chain aldehyde/alcohol/acid,and the content of branched-chain aldehyde/alcohol/acid in the treatment group inoculated with starter was significantly higher than that in the treatment group not inoculated with starter(P<0.05).Appropriate addition of leucine can improve the overall sensory quality of fermented sausage.Therefore,the quality and flavor of fermented sausage were improved under the combined action of leucine and compound starter.