Preparation Of Lactobacillus Plantarum Starter Culture And Its Antioxidative Activity

The technology of concentrated starter of Lactobacillus plantarum was developed in this paper, including optimizing filtration of the culture medium, freezing-drying protectant, cell cultivation, concentration and the lyophilization techniques. The biological function of Lactobacillus plantarum and the best dose-effect relationship were explored which served as the base for preparing Lactobacillus plantarum functional food.The optimum medium was prepared as:11%skim milk,0.5%lactose,0.5%peptone,0.8%yeast extract and1%Na2HPO4-KH2PO4,37℃incubation time12h. The viable count was1.53×109,5.43fold higher than the blank. Fermented liquor of Lactobacillus plantarum was centrifuged (4000r/min×20min), the components and dosage of the cryoprotective agents were ascertained. When using the combination of10%trehalose and4%sodium glutamate and11%skim milk, the cryoprotective agents showed the highest positive effect. Freeze drying had the survival rate of78.8%.The antioxidative activities were studied for the intact cells, cell-free extract, inactive cells and freezing-dried Lactobacillus plantarum and Lactobacillus bulgaricus. The scavenging activity of DPPH, hydroxyl radical, and superoxide anion, inhibition of lipid peroxidation, the reducing activity and chelation activity of metal ions were examined, and the difference between the two Lactobacillus were compared. The antioxidative activity of Lactobacillus plantarum was higher than that of Lactobacillus bulgaricus.The a,a-diphenyl-β-picrylhydrazyl (DPPH) free radical-scavenging ratio by cell-free extracts cells and intact of a L.p and L.B109cfu·mL-1lactic acid bacteria were47.8%and41.1%respectively, The hydroxyl radicals-eliminating ability of109cfu/mL cells were equivalent to that of lmmol/L ascorbic acid of the same volume. The superoxide anion radicals-eliminating ability of cell-free extract was48.7%, The highest reduced activity was equivalent to307±5.4μmol·L-1and263±4.3umol·L-cysteine. The chelation activity of Fe2+and Cu2+were53.6%,83.1%and28.1%,43.7%respectively. The cell-free extract was the principal element in antioxidative activity, which provided the foundation of utilization for Lactobacillus plantarum.The antioxidative effect of the Lactobacillus extracts was assessed by using D-galactose induced aging mice model. Six week animal experiment indicated that compared with the control, the antioxidative functions of serum and liver in Lactobacillus plantarum cell-free extract mice are significantly improved through enhancing SOD, GSH-Px, CAT, decreased MDA in serum and liver of rats. Serum and liver in intact cells of Lactobacillus plantarum were significantly improved through enhancing T-AOC.In conclusion, Lactobacillus plantarum has remarkable effects on antioxidation, and protection of organism. It is a potential novel bioactive substance.