Study On The Process Optimization And Shelf Life Prediction Of Fermented Mutton Jerky

As a kind of medicinal and edible quality meat,mutton is not only delicious,easy to digest and absorb,but also has good nutritional quality and health care functions,which is widely favored by consumers.However,there are currently few mutton deep-processed products on the market,and the related research and development lagging problem has been highlighted.The unpleasant mutton odor is difficult to remove,and the structure of mutton products is unreasonable,which severely restricts the development of mutton deep processing industry.Using fermentation technology to make mutton into jerky,can not only improve the flavor and texture of jerky,extend the shelf life,but also effectively remove mutton odor.A new type of fermented mutton jerky product has been developed to enrich the types of mutton products.In this study,the fermented mutton jerky was used as the research object.We investigated the fermentation characteristics of Lactobacillus plantarum,Staphylococcus carnosus and Pedicoccus pentosaceus and the feasibility of their application in mutton fermentation.The optimal combination of mixed fermentation starter was determined to further optimize the fermentation process of mutton jerky.The storage quality changes of fermented mutton jerky were investigated by using accelerated shelf-life test,and the shelf-life predicting model was established and verified in combination with chemical kinetic equation.The main research contents and results are as follows:(1)Staphylococcus carnosus,Lactobacillus plantarum and Pedicoccus pentosaceus were selected to study their fermentation characteristics.The results showed that the three strains enter a stable growth period after being cultured for 16?18 h.They had the ability to produce acid and tolerated 6%salt solution and 150 mg/L nitrite solution.Except for Lactobacillus plantarum,which had no lipase activity,the other two strains had protein and fat degradation ability,and their degradation of mutton odor fatty acids reached 60%?80%.They inhibited the growth of Escherichia coli and Staphylococcus aureus,had no antagonism,and had no other negative fermentation characteristics on the flavor and appearance of mutton products.The results of viable bacteria count were all 10~9 CFU/m L.They basically met the starter standard for fermented mutton,and could be applied to the production of fermented mutton products.(2)The different starter combinations of single strain and compound strain were used to produce fermented mutton jerky,and the difference in quality was compared.Compared with unfermented mutton jerky,water activity,water content and p H of mutton jerky decreased after fermented by 7 groups of starters.The L~*and a~*of 7 kinds of fermented mutton jerky were higher than that of unfermented mutton jerky.The shearing force,hardness,chewiness and the content of mutton odor fatty acid of fermented mutton jerky all significantly decreased.The number of volatile flavor substances and the content of aldehydes were significantly increased by fermented.Fermentation improved the sensory quality and safety of mutton jerky,and the quality improvement effect of mixed-strain fermentation was better than that of single-strain fermentation.Taken together,the mixed fermentation of Lactobacillus plantarum,Staphylococcus carnosus and Pedicoccus pentosaceus(1:1:1)produced mutton jerky with better indicators and the highest sensory score,which was determined as the optimal starter combination.(3)The single factor method and response surface test were used to optimize the fermentation process parameters of mutton jerky.The optimal fermentation process were as follows:starter strain ratio(Lactobacillus plantarum:Pedicoccus pentosaceus:Staphylococcus carnosus),1:1:2;starter Inoculation amount,2.2×10~7 CFU/g;fermentation temperature,26?;fermentation time,38 h.Under such technological condition,the shear force and sensory evaluation of fermented mutton jerky were 4989.13 g and 92.2,and the relative errors were 1.05%and 1.98%,respectively.Comparing the mutton jerky made by fermentation technology and traditional technology,it was found that the nutrition,sensory and texture of fermented mutton jerky have been significantly improved.(4)According to the results of accelerated shelf-life test,the shelf life of fermented mutton jerky at 40?,50?and 60?was 140 days,112 days and 84 days,respectively.With the increase of storage time,the p H value first decreased and then increased,the color value(L*,a*,b*)decreased continuously,and the total volatile basic nitrogen(TVB-N),thiobarbituric acid(TBA)value increased continuously.The increase in temperature accelerated the rate of change of the quality index.Person correlation analysis showed that TBA value and TVB-N content are key indicators for predicting shelf life.The shelf-life model was established by first-order chemical kinetic equation and Arrhenius equation.After error analysis and prediction comparison,it was found that the shelf-life predicting model based on the TBA value is more suitable for predicting the shelf life of fermented mutton jerky,and the relative error is within 10%,which predicted that the shelf life of fermented mutton jerky at 25?is 233 days.