Effects Of Ozone Treatment On Storage Quality Of Qiushui Pear

China is the largest pear-producing country in the world, and the annual production of pear fruit reached about 13676 thousand tons in 2008 according to the FAO. Pear fruit is popular among the consumers due to its sweetness, crispness, characteristic fragrance and slight aroma. However, pear shows a typical climacteric ripening behavior and the quality declines relate with the changes of storage environment. Studying the physiological-biochemical changes and the storage technology of Qiushui pear systematically is very important.Ozone (O₃) is a strong antimicrobial agent and oxidant with numerous potential applications in the food industry. O₃ can degrade and clear the harmful gas (ethylene, acetaldehyde etc.), and have no pollution in the environment. O₃ has been recognized as the natural green disinfectant. In this paper, the physiological qualities and the antioxidant activity of ozone-treated Qiushui pear were investigated under the room temperature and the cold storage. And the expression of genes which relate with ethylene synthesis and signaling transduction were also studied by RT-PCR method. The results were as following:1. The O₃ treatment could keep the quality of Qiushui pear better, and delay the senescence at room temperature. The high concentration of O₃ treatment (21.4mg/m³) had better effect during initial stage, but long-lasting treatment could decrease the Qiushui pear quality. The suitable concentration of O₃ (2.14mg/m³, 6.42mg/m³) treatment could keep a good quality during storage, and 6.42mg/m³ O₃ treatment was better (p<0.05).2. The O₃ treatment could result in a significant increase on the antioxidant enzyme activities of Qiushui pear, keep the higher content of antioxidant substances (total phenols, total flavones) and also inhibit the PPO activity of Qiushui pear. The high concentration of O₃ treatment (21.4mg/m³) could keep higher antioxidant enzyme activities during initial stage, but long-lasting treatment could induce the decline of the antioxidant enzyme activities during the later storage. The suitable concentrations of ozone treatment (2.14mg/m³, 6.42mg/m³) could keep a continuous rise of the antioxidant enzyme activities during storage, and 6.42mg/m³ ozone treatment was better (p<0.05). 3. The O₃ treatment maybe regulated the expression of the genes which relate with ethylene signal transduction and biosynthesis indirectly. And the O₃ treatment could regulate the ethylene biosynthesis by inhibiting the expression of P-ACS1; and also regulate ethylene signaling transduction gene expression (P-ERT, P-ERS1, P-CTR1) in order to decrease the sensitivity of ethylene.4. The treatment of low-temperature and O₃ could keep the quality of Qiushui pear better and extend the shelf-life. The different concentrations of ozone had no significant differences in the prophase of storage (p>0.05). The 21.4mg/m³ O₃ was the best treatment at the later stage of storage. Moreover, the O₃ treatment could increase the antioxidant enzyme activities, inhibit the PPO activity and delay the senescence of the Qiushui pear under low temperature condition. The effect of 21.4mg/m³ ozone treatment was the best.In a word, the suitable ozone could increase the antioxidant enzyme activity, keep the quality and delay the of the senescence Qiushui pear during storage. These results could provide theoretical foundation and technical support for the storage of Qiushui pear.