Research On The Cultivation Of Probiotics Based On Secondary Fermentation And Its Application In Cereal Meal Substitutes

Rice wine residue contains a large amount of nutrients,such as sugars,vitamins,minerals,and various amino acids.According to data,Guangdong Province alone produces hundreds of thousands of tons of rice wine residue annually,with the vast majority being used for feed production and the remaining portion treated as waste.This not only wastes resources but also brings certain pollution to the local environment.Therefore,this study aims to maximize the utilization of rice wine residue resources,fully utilize its nutritional value,and reduce environmental pollution.The specific research content is as follows:(1)Response surface methodology was used to optimize the culture process of probiotics from rice wine residue extract.The basic physicochemical components,sugars,protein molecular weight,and amino acid content of rice wine residue were determined.The rice wine residue was extracted to obtain the rice wine residue extract.Using the OD value and p H value as indicators,the growth conditions of the strain were optimized through single factor and response interviews.The optimal single factor conditions were obtained as follows: fermentation temperature of 33℃,strain ratio of 0.5:1,and rice wine residue ratio of 30%.Under the optimal conditions of a single factor,a response surface experiment was designed to determine the optimal fermentation process parameters for cultivating probiotics in liquid medium containing rice wine residue: fermentation temperature 31.6℃,proportion of rice wine residue 32.11%,strain ratio 0.8:1,and OD value 1.183.(2)Study on the Effect of Different Drying Methods on the Survival Rate of Strains.The rice wine residue was used as the protective agent for vacuum freeze drying and spray drying,and the process parameters of vacuum freeze drying were optimized.The results showed that the freeze-drying time of 12 hours was chosen as the endpoint,the addition ratio of rice wine residue protective agent was 30%,the freeze-drying thickness was 1.4cm,and the survival rate reached 62.54%.In spray drying,the survival rate was 28.5%when the proportion of rice wine residue protective agent was 7.5%.(3)Stress tolerance test of probiotic powder obtained by different drying methods.Probiotic powder obtained by vacuum freeze drying and spray drying were used to conduct simulated gastrointestinal fluid stress test and storage resistance test.The results showed that the probiotic powder without rice wine residue protective agent could not tolerate gastric juice,and the probiotic powder obtained by spray drying was more resistant to gastrointestinal juice and storage than that obtained by vacuum freeze drying.When storing probiotic powder at room temperature of 20℃ is not conducive to maintaining the survival rate of the bacteria.Between-20℃and 4℃,it is more appropriate to choose 4℃for storage considering the storage cost.(4)Characterization of physicochemical properties of probiotic powder and meal substitute powder.The particle size test showed that the particle size of the sample after spray drying decreased significantly compared with the spray drying and vacuum freeze drying β-The cyclodextrin is then dried by spray,and its particle size is smaller and more uniform;Fourier infrared test showed that the probiotic powder obtained by spray drying had lower water content and was more conducive to storage;The gelatinization test showed that the gelatinization characteristics of the powder were also different,and the peak viscosity and minimum viscosity of the powder made by spray drying were the lowest;The rheological property tests showed that the elasticity and viscosity of the meal substitute powder were greater than those of the other groups,and there was no change with the increase of the angular frequency.β-After adding cyclodextrin,the elasticity and viscosity of the sample increased,and the elasticity and viscosity of the sample after vacuum freeze drying were less than those of the sample dried by spray;The electronic tongue test showed that the samples after spray drying and vacuum freeze drying had significant differences in sour,bitter,astringent,fresh and salty taste,among which the fresh taste of the samples increased,and the astringent aftertaste values in sour,bitter,astringent and salty taste all decreased significantly,while the bitter aftertaste response value and astringent aftertaste value had no significant change;The electronic nose test showed that the electronic nose response value of rice wine dregs after different drying methods was different.The response value of probiotics after spray drying was significantly lower than that of vacuum freeze drying,and the response value of all sensors in meal substitute powder and spray rice dregs was the lowest,but the response value of probiotics after adding β-The response value of cyclodextrin after spray drying increased significantly;GC-IMS test showed that vacuum freeze drying had a higher degree of preservation of odor types,and the number of volatile substances of probiotics significantly decreased after spray drying.(5)The overall color score of probiotic meal substitute powder is between 10.9 and16.9 points,the total aroma score is between 25.4 and 28.0 points,the taste score is between 20.3 and 25.9 points,and the organizational state is between 8.1 and 18.2 points.Research has shown that the odor score and organizational state of meal substitute powder increase with the increase of bacterial powder,while the taste gradually decreases with the increase of bacterial powder.Excessive bacterial powder will affect the taste of meal substitute powder and affect the score.With the addition of probiotic powder,the stacking density and compaction density of meal substitutes continue to decrease,resulting in poor overall fluidity and low cohesion;The sedimentation rate and sedimentation water absorption rate decrease,while the dissolution rate increases;The value of a* increases first and then decreases,while the value of b* continues to decrease.Staphylococcus aureus,salmonella,mold and Escherichia coli were not detected in the meal substitute powder,which met the food microbial limit standard.