Comprehensive Utilization Of Apple Pomace Through Lactic Acid Fermentation And Studies On The Fermentation Kinetics

The comprehensive utilization of Apple pomace is the bottleneck that affects the development of apple industry.The high value utilization of Apple pomace is an important way to solve this problem.In this paper,Apple pomace was used as raw material and water as solvent to extract nutrients in the Apple pomace.The obtained extract was used as the culture medium of lactic acid fermentation to prepare lactic acid solution and bacterial powder and the fermentation conditions of lactic acid bacteria were optimized.On this basis,the optimum formula of lactic acid fermentation starter was studied,and the freeze-dried protectant in the production of bacteria powder was explored.In order to facilitate the industrialization of comprehensive utilization of Apple cinder,kinetic equations for fermentation of lactic acid bacteria were established,and also the parameters of process amplification were established.The extracted residual Apple pomace was utilized to prepare biological agents fermentated by Trichoderma,which lays the foundation for the production of biological agent of Apple pomace.The results of the study were as follows:(1)Optimization of lactic acid fermatation.In this experiment,Youbailun was used as the lactic acid fermentation agent,the concentration of lactic acid bacteria was used as an indicator,the fermentation parameters such as the inoculum size,initial pH,carbon source and nitrogen source were optimized by single factor experiments and orthogonal test.The results showed that the optimum fermentation conditions were the initial pH of 6.5,inoculation amount of0.4g/100mL,sucrose of 3g/100mL,corn syrup adding amount of 0.5mL/100mL.Under these conditions,the content of live bacteria in lactic acid fermentation broth was more than 9.43×10~8CFU/mL,the total acid content of fermentation broth was more than 7.74g/L and the yield of acid reached 6.81g/L.(2)Studies on the ingredient of lactic acid starter and its fermentation conditions of in this section,the effects of the component and proportion of lactic acid starteron the lactic acid bacteria content,sugar consumption and the acid yield in fermentation of the apple pomace extract solution were investigated.The results showed that the ideal ingredient for lactic acid starter were Lactobacillus acidophilus(L9),Lactobacillus rhamnosus(L20),Lactobacillus plantarum(L60),Bifidobacterium(BB28),Streptococcus thermophilus(L70)with a ratio of2:1:2:3:4.At the inoculation amount of 4mL/100mL,the initial pH of 6.5,fermenting for 36 h,the content of live bacteria in fermentation broth can reach1.24×10~9CFU/mL,and total acid and sugar consumption are 14.45g/L,29.37g/L respectively.(3)Preparation of lyophilized powder protector of lactobacillus probiotic:bacteria mud from lactic acid fermentatlion of Apple pomace extract was used as raw materials and the survival rate of bacteria in freeze-dried powder(R1)as the main evaluation indicator,the formulation of lyoprotectant was optimized by single factor tests and response surface test.The results showed that the survival rate of the bacteria in Lactobacillus freeze-dried powder was(82.87+4.28)%,and the survival rate increased by 68.27%compared with the blank group when the protectant are consisted of xylooligosaccharides,inulin and sodium bicarbonate,and the dosages of them are 14.5%,6.28%,and 0.92%,respectively.(4)Study on the dynamics of Lactobacillus fermentation:according to the characteristics of Lactobacillus growth and fermentation,Logistic-equation was used to simulate the growth rule of Lactobacillus,and Luedeking-piret was used to simulate the rule of lactic acid generation and total sugar consumption during Lactobacillus fermentation.The growth and metabolic dynamic models of L9,L20,L60,BB28 and L70 were constructed.The experimental data and model have a higher fitting degree and as a result,the constructed model can explain the process of cell growth,acid production and substrate consumption in a certain extent.(5)Preparation of Apple pomace bioagent:the extracted residual Apple pomace was used as a raw material and Trichoderma bacteria was selected as a fermentaion strain to prepare Trichoderma biopreparation by solid state fermentation,and the fermentation condition was optimized by a single factor experiment and response surface method with the number of spores(R3)in fermentation medium as the indicator.The result showed that the number of spores can reach 7.08×10~9CFU/g under the condition of the ratio of water to material are of 2.75,the urea addition of 1.08%and soluble starch of 1.83%respectively.The obtained bioagent is expected to be used in biological fertilizer of apple pomace production.