| Folic acid is one of the most important nutrients in human diet,and it is also a vital vitamin for all living things.It participates in many metabolic pathways in the body.The lack of folic acid will lead to a series of diseases.However,the human body can not synthesize folic acid and needs to be taken from the outside world.However,the stability of folic acid is very poor,and it is easy to be oxidized and decomposed.At present,the main source of folic acid is chemically synthesized folic acid,which has been widely used to strengthen food and prevent diseases.However,recent studies show that synthetic folic acid may have potential safety hazards,and the use of natural folic acid is limited due to its poor stability.Therefore,it is of great significance to study and apply the stability of natural folate.The main research contents and conclusions are as follows:1.In this paper,Lactobacillus sakei LZ217,a strain with high yield of 5-methyltetrahydrofolate,was selected for culture,and the bacteria were collected after expansion.The extraction conditions of 5-methyltetrahydrofolate in bacteria were studied by single factor test.On this basis,response surface analysis(RSM)was used to further optimize the extraction conditions.The optimal extraction conditions were as follows:ultrasonic power 390 W,ultrasonic time 38 min,buffer volume 16 m L,5-methyltetrahydrofolate output 70.9 ?g /500 m L of fermentation liquid.2.The results showed that the concentration of Vc and glutathione was positively correlated with the antioxidant capacity,and the effect of p H on the antioxidant capacity of Vc and GSH was negatively correlated.The higher the p H,the greater the impact on the antioxidant capacity of Vc and GSH.The protective effects of Vc and glutathione on 5-methyltetrahydrofolate were studied.The results showed that Vc and glutathione had good protective effect on 5-methyltetrahydrofolate under the conditions of avoiding light,p H =6,temperature of 25 ?,but after a period of time,they showed the phenomenon of promoting oxidation,which made 5-methyltetrahydrofolate rapidly decomposed.By exploring the effect of oxidized Vc and glutathione on the stability of 5-methyltetrahydrofolate,the results showed that both Vc and glutathione could accelerate the oxidation of 5-methyltetrahydrofolate.3.The effects of concentration,pH and mass ratio of Vc-GSH on the antioxidant capacity of Vc-GSH were studied.The results showed that the higher the concentration,the longer the antioxidant capacity was,the higher the p H was,the shorter the antioxidant capacity was.Increasing the concentration of Vc or glutathione could improve the antioxidant capacity of Vc-GSH.The effect of Vc glutathione on the stability of 5-methyltetrahydrofolate was studied.The results showed that the protective effect of Vc combined with glutathione was much higher than that of Vc and glutathione alone,and it could effectively avoid the oxidation promoting effect of VC and glutathione.The results showed that Vc and glutathione had antioxidant effect on each other,which preliminarily explained the mechanism of Vc and glutathione combined action.4.The stability of 5-methyltetrahydrofolate was enhanced by Vc and glutathione.5-methyltetrahydrofolate extracted from bacteria was applied to milk with 0.1% added The stability of 5-methyltetrahydrofolate in milk was studied by using Vc and 0.2 g/L glutathione as protective agent.The effects of temperature and light conditions on the stability of 5-methyltetrahydrofolate in milk were studied.The results showed that the retention rate of 5-methyltetrahydrofolate was 76.16% at 25 ? for 18 days,while 86.21%at 4 ? and 86.21% under Indoor natural light 64.16% and 76.16% respectively.The application of 5-methyltetrahydrofolate in milk was basically realized. |
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