| Lobster sauce is a traditional Chinese fermented soy product that has been used as both medicine and food.In order to achieve stable,large-scale,standardized production of Guizhou Sansui characteristic bacterial lobster sauce products,on the basis of retaining the original flavor,we strengthened the excellent strains,achieved pure or mixed fermentation,controlled the quality stability of lobster sauce and reduce poisonous and harmful substance and improved the safety of products.In this paper,three excellent strains were isolated from Guizhou Sansui natural fermented lobster sauce,and the composite starter was prepared by mixed fermentation and was applied.The research results were as followed:1.Screening and identification of dominant species from fermented lobster sauce in Guizhou Sansui.13 strains were isolated and screened from the traditional production process,inoculated into soybeans,and the sensory score and protease activity were used as indicators to carry out initial screening and secondary screening.Five dominant strains were selected and physiological and biochemical tests were carried out.Three strains?B,F and J strains?were by 16Sr DNA sequencing analysis,and they belonged to the subspecies of Bacillus subtilis,which were the dominant species of Guizhou Sansui characteristic bacterial lobster sauce.2.Preparation of bacterial type lobster sauce composite bacteria.The growth conditions of 3 strains B,F and J of Bacillus subtilis were optimized to prepare a composite starter and applied.The results showed that the best combination of the composite starter was A2B2C2D2,the optimal strain ratio was 1:1:1,the culture temperature was 35°C,the culture time was 48 h and the inoculum amount was 5%.Under this condition,the enzyme activity was 48.51 u/g.Finally,the composite starter exceled in natural fermentation and single strain fermentation by measuring protease activity,amino acid nitrogen and sensory score.3.Drying characteristics of lobster sauce and dry kinetic model establishment and quality analysis.The results showed that the drying characteristics of lobster sauce were mainly dried at reduced speed and constant speed time as short at temperature of 50?-70?and relative humidity within the range of 30%-50%.Five classical mathematical models were selected to nonlinearly fit the experimental data,and the Page was the best model for lobster sauce drying.According to Fick's second law,the effective water diffusion coefficient De of lobster sauce fluctuated within the range of 3.092×10-11-5.665×10-11 m2/s.Within this range,the effective water diffusion coefficient became larger with the increase of temperature,but with the increase of humidity was reduced.The quality of lobster sauce was analyzed by comprehensive scoring,and the highest score of lobster sauce was 0.40 at 60°C and 40%.4.Quality change and shelf life prediction during the preservation of lobster sauce.In the range of 288.15 K-308.15 K,the total number of colonies increased with the storage time extending.With the increase of temperature,the growth rate increased.The brightness decreased with the prolongation of storage time,and with the storage temperature increased the brightness was more obvious decline.According to studying the total number of colonies,chromatic aberration and sensory quality of dried lobster sauce at different temperatures during preservation,the first-order reaction equation was used to fit the variation trend of the total number of colonies during the storage of dried lobster sauce.The regression equation R2 was more than 0.90.Combining with the Arrhenius equation,a shelf-life prediction model was established.In the range of288.15 K-308.15 K,the relative error between the predicted value and the measured value is less than 10%,and they were 8.33%,0.03%,and 3.33%,respectively.The coincidence degree of them was considerable acceptability,which could effectively predict shelf life of the dry lobster sauce at 288.15-308.15 K. |
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