二氧化硫对玫瑰香葡萄果实采后保鲜的机理

The mechanism of SO_2 preserving Muscat Hamburg table grapes

以玫瑰香葡萄果实为材料,运用低温结合SO_2熏蒸的商用贮藏保鲜技术,研究采后果实贮藏中防腐保鲜剂SO_2对果皮组织氧化还原平衡、次生代谢活性的影响.结果发现:使用SO_2保鲜剂可使玫瑰香葡萄果实的货架期延长,在贮藏65 d时,对照组的好果率降至90%以下,而SO_2处理组好果率较高,在贮藏190 d时好果率仍保持在90%以上.贮藏期间,对照组与处理组次生代谢途径关键酶苯丙氨酸解氨酶(PAL)活性及次生代谢产物花色苷含量都随贮藏期的延长而下降,但SO_2处理组显著高于对照组,在检测的3个时间点处理组PAL活性分别是对照组的1.24倍、1.33倍和1.46倍,处理组花色苷含量是对照组的1.41倍、1.30倍和1.29倍.贮藏期间SO_2处理组葡萄果皮组织抗氧化能力显著增强,H2O_2含量和丙二醛含量高于对照组.研究结果表明,使用SO_2保鲜剂可使葡萄果实组织中活性氧(ROS)水平增高,抗氧化防御应答增强,花色苷含量增高;胞内ROS信号可能参与介导果实细胞抗氧化和防御应答,从而增强其抗感染能力、延缓果实细胞衰老,使果实货架期延长.

Grape（Vitis vinifera） is one of the world＇s largest fruit crops and also the most commonly consumed fruit both as fresh fruit（table grape） and processed fruit（wine, grape juice, molasses, and raisins）. Until now, SO2 fumigation is the most effective and widely used method for postharvest anti-decay and fresh-keeping of table grapes, although SO2 residue might be harmful to human health. In order to find a healthful and efficient way for grape storage, we studied the effects of SO2 preservative on oxidation-reduction equilibrium capacity and activity of secondary metabolism in Muscat Hamburg grapes during post-harvest storage. The results showed that application of SO2 preservative could extend the shelf life of table grapes. Good fruit rate in the control group dropped below 90% during sixty-five days storage, while in SO2-treated group the good fruit rate was higher and remained above 90% during 190 days storage. During storage, phenylalanine ammonia lyase（PAL） activities and the contents of total anthocyanin were decreased with the extension of storage period in both control group and SO2-treated group, but the values of PAL activities and anthocyanin contents in SO2-treated group were significantly higher than those in control group. In three different storage time; the activity of PAL in SO2-treated group was 1.24 fold, 1.33 fold and 1.46 fold higher than the control group respectively; the content of anthocyanins in SO2-treated group was 1.41 fold, 1.30 fold and 1.29 fold higher than the control group. The antioxidant capacity was increased significantly in the skins of Muscat Hamburg grape berries exposed to SO2, meanwhile the contents of H2O2 and malondialdehyde were also higher in the skins of SO2-fumigated grapes. The results indicated that SO2 fumigation triggered reactive oxygen species（ROS） production in table grapes. SO2 fumigation evoked antioxidant defense response and promoted secondary metabolism in grape berry, which could enhance its resistance to biotic and abiotic stress and delay aging, contributing to the extended shelf life of table grapes.