Preparation And Application Of Starter Culture Used For LAYU

LaYu is one of unique traditional aquatic products in China. It is popular in domestic and overseas because of its distinctive flavor, tangy, delicate, fishy and salty. At present LaYu’s manufacturing period was long, quality stability poor and so on questions by traditional fermentation. Therefore, uses vaccination fermentation technology to development high quality of fermented fish products, had the important meaning to the fermentation cured fish technique of production’s innovation and the modernization. Lactobacillus and Staphylococcus aureus were isolated and identificated from traditional fermented fish as the research object. To analyze its fermentation characteristics, optimize formula of culture medium, enrich conditions and heat-protective agents were able to preparate of good performance of the starter culture using spray drying. Study on microbe, physico-chemical components, Sensory score, chromaticity, composition, musclefibre, volatile compounds of LaYu in different fermentation conditions. Discussion on using starter culture for quick fermentation the of LaYu, to provide the theory basis and the technical parameters for machining technological innovation about LaYu. The main results were summarized as follows:(1) Bacterial strains were obtained and used to preparate starter culture for fermented fish products. Bacterial strains were isolated from the traditional fermentated fish products, used to preparate starter culture. They were identified to using the method of molecular biology, were Pediococcus acidilactici, Lactobacillus plantarum, Staphylococcus epidermidis, Staphylococcus sciuri, Staphylococcus xylosus. Study on the nitrite and salt resistance capacity, produced acid and free amino acid ability, activity of protease and lipase fermentation characteristics.(2) The development of starter culture was used in fermented fish products. Enrich bacterial strains of medium were NA to make basis into adding 3% tomato juice,5% fish gravy and 10%in malt juice,30℃fermentation 48h, cell concentration was 108cfu/g. Enrich conditions was 4000r/min centrifugal 10min at 15℃. With 1.5% glycerin,1% sucrose,3% trehalose and 3% malt dextrin as heat-protective agents in spray drying, the survival rate of lactic acid bacteria and staphylococcus were 15.49% and 16.30% respectively.(3) The machining process of vaccination fermentation were determined for LaYu. Adding starter culture too much, fermented time and temperature were to long or high, ability of acid production is enhanced. Shortens fermentation time and microbial fermentation, the NaCl content of was the lower in fermented fish products. The biggest influence of total acid and TVB-N value for fermentation temperature in fermented fish products. And effect of dry temperature and humidity to fish drying rate, the higher is the temperature, the faster moisture losses. The optimum fermenting craft parameter of the vaccination fermented fish was proportions of PL:PA:SX=10:10:1, vaccination 108cfu/ 100g, fermentation 24h at 12℃after 30h heated-air drying at 10℃.(4) The quality characters of vaccination fermentation were determined for LaYu. Microbial group of type and quantity of LaYu were changed by Vaccination fermentation, thereby affecting the physical quality, petrophysical property, flavor substances ultimately led to the difference of organoleptic quality. After vaccination of fermentation is ten times than the natural fermentation; Natural fermentation need to long time and high temperature, so the content of salt (7.81%) higher vaccination fermented fish products significantly. The total acid content of Natural fermented fish below vaccination fermented, and natural fermentation because the growth of miscellaneous bacteria, killing TVB-N value was higher. Muscle fiber become closely of longitudinal section tissue after fermentation, muscle fibers of the space smaller. Meanwhile vaccination fermentation microbial propagation fast, fish protein decomposition of protease into small molecular peptide and amino acid more thoroughly. Separabled 36 kinds of volatile compounds, including 23 species of hydrocarbons,5 kinds of alcohols,3 species of ketone,4 species of aldehyde, esters 1 kinds from LaYu by Vaccination fermentation.