Screening Of Starter Cultures From Yun-nan Cured Beef And Study On Action Mechanism In The Fermented Sausage

Fermented meat product has been welcomed in developed countries because of its special health care and nutritional function.After entering WTO,the meat market in china also entered a new time,the demand has changed from the amount and materials to quality and products.With the improvement of the life level, people need a new type meat product urgently,which have a special flavor and certain health care effect. Under the new situation,Producing high-quality fermented meat products have very important meanings for the development of our livestock husbandry.It can also satisfy the urgent needs of the customers.Excellent meat starter culture is the foundation of producing high-quality fermented meat products,the traditional fermented meat product has a long history in china,and it is numerous in variety,it has a wide prospect to screen fine strains used as a new type meat starter culture.In this test,we screened excellent mixed starter culture which can used in industrial production from yun-nan cured beef,and used it in fermented sausage.Then we do the analysis on physico-chemical,biochemical and microbial indexes in different batches during ripening,discuss the effect mechanism which the starter culture has done.The study offers a theoretical direction for production practices.The report includes several parts as follows:1.5 strains of lactic acid bacteria were isolated and purified from Yun-nan cured beef,they all have the follow characteristics:have Salt and nitrite tolerance;produce no NH₃ from arginine;produce no gas(CO₂) from glucose;have no decarboxylase activity;produced no H₂S,H₂O₂;produce no slime production;produce acid quickly and have a good acidifying capacity;inhibit E.coli and S.aureus.Then discusse the effect of temperature and broth on the growth,analysis the growth and acidifying condition,make sure that NR33 and NR52 were the lactic acid bacteria that we wanted.The two strains were preliminary identified:NR33 was the lactobacillus delbrueckii,NR52 was lactobacillus casei.2.Besides the above characters which the lactobacillus have,3 strains of staphylococcus were selected, which have nitrate reductase activity,catalase activity,protease activity and lipase activity.By studying its growth condition,chosen NA21,NA73 as the objective bacteria.According to the pictographic,physiology and biochemistry characteristics,NA21,NA73 were the staphylococcus carnosus.3.Mixed lactic acid bacteria and staphylococcus in simulated broth,searching on its growth tendency in 48h,found that NR33 has a significantly inhibit function on NA21 and NA73.When mixed lactobacillus casei NR52 and lactic acid bacteria together,both of them were keeping a high and stable level.So we used lactobacillus casei and staphylococcus carnosus as the meat starter culture.4.Fermented sausages were produced with selected meat starter culture,made 5 different batches.Then we do the analysis on physico-chemical,biochemical and microbial indexes in different batches during ripening,indigenous microbe made a significantly improvement on sensory characters of the product. Lactobacillus casei accelerated the death of enterobacterium,produced acid quickly,decreased the AW value and the total volatile basic nitrogen,improved the security of fermented sausage,it also improved the organization structure of the product.Staphylococcus carnosus improved the color of fermented sausage, Muscle restriction enzyme have significantly effect on protein and fat hydrolysis,the effect of microbial enzyme is not significantly.The total acceptability of the product which added the mixed starter culture is the highest.In summary,this test screened excellent native stain from traditional fermented meat,changed the scarcity condition of fermented meat starter culture,provided a science and theory base for excavation and innovation of fermented meat product microorganism,it has a very important meanings on improving the development of the fermented meat fabrication industry.