| Both yogurt and cheese are the traditional dairy products in Xinjiang, which contains a lot of probiotics. As the oxidation process is necessary for the body’s metabolic activity in recent years, more and more researchers begin to study the antioxidant effect of lactic acid bacteria. Although our body can withstand part of the immune damage, but they cannot be defense all of these injuries, you also need to fix on them. All these above need the body’s intake of antioxidants to keep the balance of metabolic activity.However, when people intake of the antioxidants, they have to worry about whether they were safe. So, the researchers have to explore the natural antioxidant deeply in time. Lactic acid bacteria(LAB) has become the representation of natural antioxidant. There are a large number of studies reported all kinds of physiological functions of lactic acid bacteria at home and abroad, such as: anti-aging, anti-oxidation and so on. The study use all 20 strains of lactic acid bacteria, which were isolated from yogurt and cheese, to preliminary discuss and explore their antioxidant capacity from both in vitro and in vivo validation, all those above laid the foundation for the development of functional dairy products.According to the in vitro resistance to hydrogen peroxide, we selected 7 strains of LAB from 20Lactobacillus: Pediococcus acidilactici 1-1, Weissella cibaria 13-2, Lactobacillus panis 2-5, Lactobacillus plantarum 12-4/15/24-7 and Enterococcus durans 19-10. Then all of those strains and their cell-free extract( CFE) were used to study the ability of hydroxyl radical scavenging, DPPH radical scavenging,superoxide anion radical ability, reducing activity and chelating ability of ferrous ion. The results showed that all strains have certain antioxidant activity. However, different strains have different abilities, even the same kind of lactic acid bacteria such as plant lactobacillus, also have a big difference. Among all of LAB,the Lactobacillus panis had the highest hydroxyl radical scavenging ability and reduction ability, the Weissella cibaria DPPH scavenging ability were relatively strong, Lactobacillus plantarum superoxide anion radical and ferrous ion chelating ability were relatively high.In the next experiment, we selected 3 typical strains from 20 lactic acid bacteria strains as the representative strains, determined the effect factors of their antioxidant capacity. According to the study, we found that 37 ℃, the 16 h of culture time and 8 of p H, strains had the highest antioxidant activity, and increase with the increased concentration of bacteria.In addition, our study further explores the antioxidant affecting factors of lactic acid bacteria in fermented milk, and determined the antioxidant capacity, the DH and the number of living bacterium after fermentation. The results showed that the antioxidant activity increased with the DH in the fermented milk. But the number of living bacterium had nothing to do with them.In the end, we used Lactobacillus plantarum to do the animal experiment. Not only did strain have a high antioxidant activity level, but each component of inactivated strains had some antioxidant capacity.The activity of super dismutase(SOD), malondialdehyde(MDA), gultathione peroxidase(GSH-PX),alanine aminotransferase(ALT), aspartate aminotraferase(AST), albumin(ALB), total protein(TP) andtrilyceride(TG) of whole cell and their extracts were analysis. The mice model was destroyed by carbon tetrochloride. Compared the sample group and the model group, the dates showed that: the concentration of ALT, AST, TG, ALB, TP, TC in the serum and the MDA, SOD, GSH-PX in liver tissue were significant difference(P < 0.05). Lactic acid bacteria in the silymarin group was better than BS, IC, CFE groups when protect liver. Compare with the three sample groups, we found that the BS group is better than the other two groups, especially the related data were similar with the blank group in the liver lipid peroxidation(P > 0.05). |
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