The Effecets Of Bi-component SO₂-ClO₂on Postharvest Quality Of Red Globe Grape Fruit During Storage

Xinjiang is one of the main grape producing regions in our country, with itsexcellent quality and famous in the world. Grape commercial storage at home andabroad is more than98%use the SO₂combination with fast and slow release way tofumigation fresh grapes. But there are some problems in the process of using SO₂.Thefumigation concentration is too low to meet the anti-corrosion aim, whenconcentration is too high and easy to make fruit grain of fade bleaching, and the fruittissue structure is seriously damaged, result in the poor food safety. Chlorine dioxide（ClO₂） is the United Nations world health organization to confirm a safe, efficient,broad-spectrum and powerful non-toxic disinfectant, the United Nations healthorganization （WHO） has listed as the A1level security disinfectant. This study on thebasis of previous work on the preparation of the Bi-component SO₂-ClO₂preservativeand use the red globe grape as test materials, then analyses the influence ofBi-component preservative on postharvest quality. The effect on the senescence,soften related enzymes and anthocyanins degradation dynamics model were studied ofred globe grape, to explore Bi-component SO₂-ClO₂preservative to reduce SO₂residue of grapes, keep the fruit senescence softening mechanism. The main resultsare as follows:1. Through screening and optimization of SO₂with ClO₂agent formulaproportion, determining the optimal formual for SO₂/ClO₂generating agent massration was10/1. Using the thermal technical preparation of Bi-component SO₂-ClO₂preservative and applied for table grape experiments.The results showed that theSO₂-ClO₂preservative reduces the browning and the decay rate compare to thecontrol, to inhibit the decline of the pH、soluble suger and titratable acid. Theprocessing grape berries maximum SO₂residues was41.52mg/kg in the end of theexperiment, below the national standard requirements of50mg/kg. It is demonstrated that Bi-component SO₂-ClO₂preservative can effectively reduce the SO₂residues,and extend the shelf life of red globe grape.2. Using Bi-component SO₂-ClO₂and single component SO₂preservatives toprocess the red globe grape fruit, the MDA（malonaldehyde） content in control andprocessing fruits showed a gradually rising trend. But Bi-component SO₂-ClO₂preservatives inhibit fruit content of MDA accumulation speed and maintaining thestability of the membrane. At the same time it can induce increase in the activity ofSOD （superoxide dismutase）, POD（peroxidases）, APX（ascorbate peroxidase）, inhibitactivity of CAT（catalase） decreased. The H₂O₂and O2-.generated content inBi-component SO₂-ClO₂preservatives were lower than the control. It is imply that theBi-component SO₂-ClO₂can reduce the accumulation of H₂O₂and O2-.content ingrape berries, reduce the toxic effects of H₂O₂and weaken the damage of free radicalson membrane, thereby delaying the senescence speed.3. The Bi-component SO₂-ClO₂treatment keep the firmness of grape forreducing the degradation rate of the original pectin, decreasing the rate of solublepectin. While suppressing the pectin methylesterase （PME）, and polygalacturonase（PG）, pectate lyase （PL）, cellulase （Cx）, and β-galactosidase（β-Gal） several cell wallsoftening enzyme activity, decreasing the degradation of pectin and cellulose, andmaintain fruit firmness to delaying fruit softening rate.4. Anthocyanins in Red Globe grape were studied at different temperatures, thethermal stability of the results show that the degradation rate increases with theincrease of the temperature, the half-life gradually increased with the increase oftemperature is reduced, in line with the Arrhenius law. Through the study on thethermal stability of grape anthocyanins, deduced its thermal degradation kineticsreaction equation, and then Red Globe grape anthocyanins,thermal degradationkinetic model was primarily established, through the model can predict the storage period and shelf life related with color, to effectively control the degradation of grapeanthocyanins and provide theoretical basis and to extend the storage period.