Studies On Screening Of Starter Culture And Process Characteristics Of Cured Fish

Crude fish is a unique flavor traditional aquatic product. In this paper,the process conditions on wet salted fish, the fermentation process of grass carp inoculated with Lactic acid bacteria was studied. And systematically analyzed total plate counts, total volatile basic nitrogen(TVB-N),thiobarbituric acid(TBA), changes in protein and free amino acids during processing and storage of the fermented grass carp.Finally,the strains of Staphylococcus were screened of the good flavor cured fish in the natural fermentation, mixed them with Lactic acid bacteria to ferment the grass carp, then the optimal fermentation was fixed. It provides a theoretical basis for the preparation of cured fish inoculated fermentation and production of fermented fish products.l.Chosed the sodium chloride content, permeability and TVB-N value as the index, liquid-solid ratio,concerntration,temperature and time of curing as the experimental factors, the optimize curing condition was fixed through orthogonal test:4℃,10%sodium chloride content, the liquid-solid ratio of2:1,and soaked for4hours under these conditions.2.Four strains of Lactic acid bacteria Pediococcus acidilactici(PA), Lactobacillus sp.Lo3(LL), Lactobacillus sp.B5407(LB),and Lactobacillus.sakei(LS)which had high fermentation properties were used to ferment the grass carp, chosed pH value and the amount of free amino acids as the index, the fermentation temperture,inoculum concentration, time and the amount of glucose added as factors in process optimization test of fermented grass carp. Analysis of variance suggested that:PA30℃,2d,3%inoculum concentration and5%addition of glucose;LL30℃,2d,1%inoculum concentration and4%addition of glucose;LB30℃,2d,3%inoculum concentration and5%addition of glucose;LS30℃,2d,2%inoculum concentration and4%addition of glucose.3.The microorganisms and physico-chemical changes in the processing and storage were studied under the optimized fermentation conditions. As using Lactic acid bacteria to ferment the grass carp, it reproduced so fast that became the dominant strain, resulting the rapid decline of pH value,and this inhibited the growth and reproduction of spoilage bacteria effectively;reduced the accumulation of TVB-N,TBA values.After had been fermented by microorganisms,the free amino acids of Grass carp were increased significantly. The growth rate reached maximum in the maturation process,from the initial0.62g/100gDM to1.65～1.98g/100g DM at20d.SDS-PAGE electrophoresis showed that, with fermentation,the protein was gradually degraded, especially in the fermented group.4.Three strains of Staphylococcus were selected from a good local flavor of cured fish in the natural fermentation,NO.1,62strain were Staphylococcus simulans, NO.22strain was Stapyloccus xylose by the biochemical identification.NO.1,22,62strain reached the stable phase at16h,10h and12h,respectively;the OD value of NO.1,62strain were maximum at pH7.5,and NO.22strain at pH7;three strains grew at20～40℃,endured8%sodium chloride and0.02%nitrites.5.The lactic acid bacteria PA, LB, LS strains were mixed fermentation with NO.1,22,62strain, chosed the pH value, TVB-N values and free amino acid as index, the best combination LB-NO.22was selected to fermention,and the optimization of fermentation conditions was obtained:fermentation temperature30℃,2%inoculums, bacteria ratio of2:1,fermented2d.