Study On Lactobacillus Delbrueckii's Lactic Acid Fermentation Conditions And Optimization Of Its Technology Process

The thesis was designed to analyze the effects on fermentation in order to produce lactic acid effectively and establish a low-cost but High Yield fermentation medium for industrial production, which made use of the"protein-eliminated"rice saccharificate as carbohydrate source.Lactic Acid is an important biochemical product, which is widely used in food, chemical engineering, and pharmaceutical industry. In recent years, people pay more and more attention to lactic acid because of its character that could be used for synthesizing Biodegradable poly(lactic acid).Lactic acid is hence going to form a huge potential market. Lactobacillus delbrueckii(LAB) that was commonly used in current lactic acid industry was applied in this research. The fermentation characteristics, fermentation conditions and rice saccharificate liquid medium were studied. The detail content were as follows:1,The qualitative-analysis method of Lactic acid by the use of TLC and quantitative analytical method by the use of p-hydroxybenzoic were set up. The results showed that Qualitative-analysis method was good; quantitative analysis method was simple, stable and had high precision and nice fidelity, which could be applied to the determination of lactic acid.2,The fermentation characteristics and culture conditions of LAB were studied, the best fermentation conditions were as follows: Aerobic environment for the plates, 16 hours of inoculum Ages, 10% of inoculation size, 120 ml/250 ml of loading, 50 rpm of shaking speed, 6.0 of pH value, adding a one-time 50 g/L (5%) of calcium carbonate after 6 hours.3,The effect of medium components on the yield of lactic acid were also studied. The best components of fermentation medium were derived from orthogonal experiment: the"protein-eliminated"rice saccharificate containing 8% of glucose, 25 g/L of soy bean cake, 0.15 mg/L of nicotinic acid, 0.0015 mg/L of biotin,0.015μg/L of Vitamin B₁₂, 0.5 g/L of Mg²⁺, 30 mg/L of Mn²⁺,2 g/L of KH2PO4.Under optimal conditions, 67.5 g/L of lactic acid was produced from 80 g/L glucose after 72 h fermentation with the mass yield of 83.5%.4,A preliminary study on the rice saccharificate liquid medium containing different amounts of rice residue protein was developed. The results showed that the content of residue protein remaining in rice saccharificate played an important role on the yield of lactic acid fermentation.