Study On Fermentation Mechanism Of Sand Crab Juice And Its Process Improvement

Sad crab juice is a famous fermented aquatic product seasoning in the Bei Hai.It is fermented by traditional fermentation process,Sad crab juice has unique aquatic flavor,However,sand crab juice has problems such as unclear fermentation mechanism,poor product stability,single product,and poor color appearance.This paper simulates the traditional sand crab fermentation of Sad Crab Juice,using 16 Sr DNA sequence analysis,headspace solid-phase microextraction-GC-mass spectrometry,electronic nose and electronic tongue,etal.Studying the changes of microorganisms and physical and chemical indexes in the fermentation process of sand crab juice,explore the fermentation mechanism of sand crab juice.Studying the effect of adding exogenous microorganisms on the physical and chemical indexes and flavor components of sand crab juice;Studying the decolorization,deodorization and preparation of sand crab juice.Lay a certain foundation for the improvement of the fermentation process of sand crab juice and the development of a series of products.The main findings are as follows:(1)The pre-fermentation mainly microorganisms of sand crab juice were Staphylococcus equorum subsp and Staphylococcus arlettae.Later,Staphylococcus saprophyticus,Salinicoccus amylolyticus and Bacillus cereus are present,and Staphylococcus equorum subsp is the dominant bacteria in the fermentation process.During the fermentation of sand crab juice,the amino acid nitrogen content increased rapidly,and the growth rate were slow in the later stage,eventually reaching 0.43 g/100 m L.The total nitrogen and free amino acid content increased first and then decreased,which were 0.72 g/100 m L and 2.99 g/100 m L,respectively.In the late stage of fermentation of sand crab juice,The volatile base nitrogen content increased rapidly to 105 mg/100 m L,which brought certain safety hazards to the product.The changes of physical and chemical indicators in the fermentation process of sand crab juice are related to microorganisms.The fermentation is the result of the interaction of endogenous enzymes and microorganisms in sand crab.(2)Improve the flavor of traditional fermented sand crab juice by adding microorganisms,The results showed that the addition of different strains of fermented sand crab juice resulted in significant changes in volatile flavor components.The best effect was four strains of sand crab juice and Rust yeast,Lactobacillus plantarum and Staphylococcus xylosus,compared with the traditional fermented sand crab juice,the content of amines was reduced,the flavor component was increased,and the increased flavor component were:6-methyl-2-heptanol,Octanol,3-cyclopentyl-1-propanol,6-methyl-2-heptanone,(1,1'-bicyclopentyl)-2-one,isophorone,2-methyl 2-pentene,2,3-dimethyl-2-butene,butyric acid-3-hexene ester.The addition of Rust yeast,Lactobacillus plantarum and Staphylococcus xylosus decreased the p H of the sand crab juice and then increased,and its amino nitrogen content same as traditional fermentation,lastly.(3)Decolorization and deodorization treatment of sand crab juice with filter paper and ?-cyclodextrin,The results showed that the decolorization effect is better with filter paper,and the amino acid nitrogen loss rate is 15%.0.3% ?-cyclodextrin was added and the temperature was 75 °C for 25 min,the depurination effect was the best.By adding 2.0% fish dew peptide and 3.0% sodium nucleotide,the amino acid content of the crab juice reached 0.55 g / 100 m L;Through the analysis of electronic tongue,the blended sand crab juice has great changes in bitterness,umami,salty taste and richness.According to the analysis of GC-MS,the content of amines in the sand crab juice was decreased,and the alcohol content increased.The main alcohols were isoamyl alcohol,6-methyl-5-hepten-2-ol,guaiacol,1-nonanol,dodecadienol,3-cyclohexene-1-methanol,6-methylheptanol,carbonyl compounds are reduced,phenolic compounds were increased,and the flavor of sand crab juice was increased.The dominant microorganism in the fermentation process of sand crab juice is Staphylococcus equorum subsp,Staphylococcus arlettae,Staphylococcus saprophyticus,Salinicoccus amylolyticus and Bacillus cereus;By adding microorganisms separate from sand crab juice and Rust yeast,Lactobacillus plantarum and Staphylococcus xylosus fermented sand crab juice,the amines of sand crab juice were reduced,and the types of flavor substances were increased;Decolorize crab crab juice with filter paper,add 0.3% ?-cyclodextrin and embed at 75°C for 25 min,After adding 2.0% fish sauce peptide and 3.0% sodium nucleotide,the amino acid nitrogen of the sand crab juice products is 0.55 g / 100 m L.The flavor,taste and color are greatly improved compared with the original products.