| The grape of Xinjiang, one of the major grape producing areas in China, isfamous in the world for its excellent quality. To prolong the file of grape, SO2ismainly used on fresh table grape commercial storage at home and abroad. However,there may be some problems in the process of using SO2. The SO2concentration mustbe control seriously, when it is too low to meet the antimicrobial preservation effect,and too high and easily lead to fruit bleach problem. Chlorine dioxide (ClO2) isconfirmed as a safe, broad-spectrum and powerful non-toxic disinfectant by theUnited Nations World Health Organizationt. Our group developed bi-componentSO2-ClO2preservation treatment to overcome the defect of these two components. Inthis study, thompson seedless and munage grapes were treated with SO2-ClO2, theSO2-ClO2treatment impact on the postharvest quality and functional ingredients ofgrapes was investigated which can provide a theoretical basis for the development ofgrape industry.The main findings are as follows:1. Thompson seedless and munage grapes were treated with bi-componentSO2-ClO2and single-component SO2at first, and effects of them on harvest-relatedquality parameters of grapes during storage were investigated. The results show thatbi-component SO2-ClO2can reduce the amount of SO2residues in grape berries,delay nutritional material of fruit vitamin C, soluble sugar and titratable acidity (TA)rate of decline. It can be able to maintain a higher fruit firmness, and also effectivelyreduced fruit weight loss rate, decay rate, shattering rate and browning index toimprove the quality parameters of grapes during storage.2. Grapes were treated with bi-component SO2-ClO2and single-component SO2,the effect of two treatments on the reactive oxygen species and the related antioxidantenzymes in grapes were investigated. The results showed that SO2-ClO2treatmentcould inhibit MDA accumulation in fruit, protect the integrity of the cell membrane ofthe fruit, while promote the speed of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activity, delay decreased level of ascorbate peroxidase (APX) activity.Compared with the control and SO2treatment, SO2-ClO2treatment can keep the fruitsof lower H-·2O2, O2content. Indicating that bi-component SO2-ClO2treatment canslow the reactive oxygen species poison fruit tissue and improve the activity ofantioxidant enzymes, anti-aging process of the fruit.3. Solid phase extraction (SPE)-high performance liquid chromatography (HPLC)method was established to determine the functional ingredients resveratrol compoundin grape skin. Chromatographic conditions are: stationary phase: Platisil ODS C18column (250mm×4.6mm,5μm i.d.), mobile phase:40%acetonitrile. In theconcentration range of0.2~50.0μg/mL, standard and peak area has a good linearcorrelation coefficient was0.9995, detection limit was0.05μg/mL, the averagerecoveries was between90.0%~98.8%, RSD was3.51%~5.76%. The results showedthe method can effectively eliminates a large number of interfering components in thesample.4. The ultrasonic assisted organic solvent extraction was used to extractresveratrol from2grape skins. The extraction condition was optimized includingextraction solvent, solid-liquid ratio, extraction times, extraction temperature, andextraction time. By orthogonal optimization and validation experiments, the optimizedcondition was below:70%ethyl acetate as the extraction solvent, solid-liquid ratio of1/10,2times extraction, extraction temperature is20℃, extraction20min. Underoptimal conditions, the resveratrol average extraction rate of grape skin was47.97±0.48μg/g.5. The effect of different treatments on fruit resveratrol content change and relatedsynthase enzymes was studied. The results showed that bi-component SO2-ClO2treatment could promote the synthesis of resveratrol, maintain the stability offunctional ingredient, and also provide a theoretical basis for extending the shelf lifeof grapes effectively. |
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