Studies On Non-Sulfur Dioxide Postharvest Techniques Of Table Grapes

At present, preservative which can release SO₂ is most widely used as a postharvest antidecay and fresh keeping method for grapes.However, in view of SO₂ injury to grape berries, SO₂ acidic gas corrosion to metallic equipment in storeroom, SO₂ pollution to environment and effect on human health, it is imperative to seek a successful preservation methods instead of SO₂. In this paper, the effects of 1-MCP combined with chlorine dioxide treatment, heat shock (hot-water) treatment, heat shock (hot-water) combined with other treatment on post-harvest storage quality changes were investigated in order to choose a postharvest antidecay and fresh keeping method instead of SO₂ .The main conclusions are as follows:1. Incorporating 2.4μl/L 1-MCP fumigated for 8 hours at room temperature and then 1g/Kg ClO₂ fungicide treatment.After 105 days, decay rate of combined treatment was 17.7%,which was significantly lower that of control or other treatments. With 1-MCP treatment alone on Red globe grapes, there was no antiseptic effect; with chlorine dioxide treatment alone the content of VC could not keep effectively and the increasing of MDA content could not be controlled well either. Combined treatment overcome the deficiency of only one single treatment, could effectively keep the content of titration acidity, sugar in berries and chlorophyll in stalk, and also firmness of berries could be well maintained.2. The effects of heat shock on shelf-life quality of Red globe and Kyoho gapes were investigated. Results showed that: with Red globe gape immersed in 50℃hot water for 1min and Kyoho gape immersed in 50℃hot water for 1min, 55℃hot water for 1min could control the decay effectively. The content of chlorophyll in stalk and firmness, VC content of berries could be well maintained also.3. Results showed that: incorporating hot water (50℃1min) with other treatments (10% ethanol, 1% calcium lactate, 1% calcium chloride, 2% sodium diacetate) could control the decay of Kyoho gape at lower level than that of control. After 100 days, the decay rate of hot water with 11% calcium chloride was 11.7%, while those of control, hot water treatment and SO₂ treatment were 82.7%, 35.3%, 16.1% respectively. Hot water with other treatments could keep the content of titration acidity, sugar in berries and chlorophyll in stalk. And also firmness of berries could be well maintained. Among the treatments, hot water combined with 1% calcium chloride was the most effective method.4. In conclusion, the postharvest antidecay and fresh keeping effect of 1-MCP combined with chlorine dioxide treatment and hot water combined with calcium chloride treatment are equal with or even better than SO₂ treatment, so the two methods can be used to grapes as non-sulfur dioxide antidecay and fresh keeping methods.