The Antibacterial Action Of SO₂ In Grape Preservation And Evaluation Of Antioxidant Function Of Peel Pigment

Grape is one of the most important fruit crops in the world.There are many bioactive substances in grape peel,which have the effect of antioxidant activity and scavenging free radicals.Grape is susceptible to fungal infection on postharvest,Botrytis cinerea is one of the main destructive fungus,which can reduce the nutrition and value of commodities of grape.SO₂ preservative is the most effective grape preservative so far,but its sulfur residue problem has attracted worldwide attention.Therefore,it is particularly important to establish low-sulfur preservation technology.Muscat Hamburg table grapes were used as experimental material in this article,the effect of Na₂S₂O₅soaking treatments on pathogenic bacteria in vitro experiments and on the preservation effect in vivo experiments were carried out in this study.In addition,grape peel pigment was extracted and its antioxidant function was studied in animals in order to provide experimental basis for the application of grape peel pigment.The main results are as follows:?1?Inhibitory activity of SO₂ preservative on Botrytis cinerea of Muscat Hamburg table grapes:the antibacterial effect of different pH,concentration and treatment time of Na₂S₂O₅ at 25?or 4?in vitro experiment were carried out in this section.The results showed that different concentration of Na₂S₂O₅?pH=4.00?for 1 h?dealt with spores,cultivated 48 d at 25?,the growth of Botrytis cinerea of control group was 7.65 cm;The 300 mg/L was4.55 cm and the growth inhibition rate was 40.5%;The 600 mg/L group was only 1.8 cm and the growth inhibition rate was 76.5%.600 mg/L was more effective than 300 mg/L.Na₂S₂O₅?300 mg/L,pH=4.00?dealt with spores for 1 h,3 h,5 h respectively,cultivated 48 d at 25?,the growth of Botrytis cinerea of 1 h group was 4.55 cm and the growth inhibition rate was 40.5%;The 3 h group was 2.35 cm and the growth inhibition rate was 63.8%;The 5 h group was 0cm and the growth inhibition rate was 100%.The inhibitory effect of 5 h group was higher than that of other treatment groups.Different pH of Na₂S₂O₅?300 mg/L,for 1 h?dealt with spores,cultivated48 d at 25?,the growth of Botrytis cinerea of pH=4.00 group was 4.55 cm and the growth inhibition rate was 40.5%;The pH=3.00 group was 3.05 cm and the growth inhibition rate was 52.7%.pH=3.00 group was more effective than pH=4.00 group.Na₂S₂O₅?300 mg/L,pH=3.00,for 1 h?dealt with spores,cultivated 48 d at 25?or 4?,visible mycelium could be observed at 25?,no visible mycelium could be observed at 4?.To sum up,the concentration of Na₂S₂O₅ was increased,the time was prolonged or the pH was decreased so that bacteriostatic effect of Na₂S₂O₅was significantly enhanced.Combined with low temperature,the inhibition effect of low concentration Na₂S₂O₅ can be enhanced.The study found that no visible mycelium could be observed after Botrytis cinerea spores were incubated with 300 mg/L Na₂S₂O₅ for 1 h at 4?.The results provide a scientific theoretical basis for the establishment of low-sulfur preservation technology for storage of table grapes.?2?Effect of SO₂ preservative on Muscat Hamburg table grapes storage:The results in vitro antibacterial experiments were conducted,so the Na₂S₂O₅concentration of 300 mg/L for 1 h was tested in vivo and further studied the effect of different pH?pH=5.00,4.00,3.50?solution on storage effects of grapes.Results showed that compared with the control group and other treatment groups,pH=4.00 group had the best storage effect,which the good fruit rate,H₂O₂ content,PAL activity increased significantly and weightlessness rate,PPO activity,fruit pathogen quantity significantly reduced.The storage effect of the treatment group with pH=5.00 was not significantly different from that the control group.The pH was too low in the treatment group with pH=3.50,which made the fruit acidic and the storage effect was less than that of the pH=4.00 group.Within a certain range,the lower pH of Na₂S₂O₅ were treated,the stronger storage effect they owned,The results provide effective technical guidance for the establishment of low-sulfur preservation technology.?3?Antagonistic effect of peel pigment on mice injury induced by arsenic exposure?As?:mice were exposed to water containing 10 ppm As for6 weeks,at the same time 50%concentration of breakfast powder or 180mg/L anthocyanin was intervened.After the end of the experiment,the relative antioxidant indexes were determined.Results showed that As to the hearts of mice was not serious,but As to the large intestine,small intestine,spleen,lung was serious.Compared with the control group,superoxide dismutase?SOD?activity,glutathione?GSH?content of As group decreased significantly and hydrogen peroxide?H₂O₂?content,malondialdehyde?MDA?content of As group increased significantly;SOD activity and GSH content of two intervention groups was significantly higher than that of the As group and H₂O₂ and MDA content was significantly lower than that of the As group.The results showed that both intervention groups could significantly reduce the oxidative damage of As to the large intestine,small intestine,spleen and lung.The results provide an experimental basis for the application of peel pigment.