Chitbanchong W, Sardsud V, Whangchai K, Koslanund R, Thobunluepop P
Postharvest Technology Research Institute, Chiang Mai University, Chiang Mai, Thailand.
Pak J Biol Sci. 2009 Nov 15;12(22):1438-47. doi: 10.3923/pjbs.2009.1438.1447.
The experiment of Longan fruit cv. Biew Kiew, untreated (control) and treated with SO2 treatment were stored under 2 +/- 2 and 7 +/- 2 degrees C for 0, 2, 4, 6 and 8 weeks were studied. The treatment of fresh longan fruit with SO2 fumigation combined with the suitable storage condition improved the overall longan fruit quality, especially on inner and outer peel tissue and aril color than no SO2 treatment. Treatment stabilizes peel color with no subsequent loss of color during storage (fruit color were bright-yellowish color). When the fruit showed during SO2 treatment, increasing of storage duration and temperatures, the dark color of inner and outer peel of longan fruit was appeared, this was correlated with the increasing of PPO activity. The activity of PPO enzyme in control fruit (no SO2 treatment) gradually lower than SO2 treatments. Fruit exposed to cool storage temperature (2 degrees C) exhibited a lower PPO enzymatic activity compared to those kept in high storage temperature (7 degrees C). Moreover, PPO enzymatic activity significantly increased over the storage durations The additional SO2 treatment no subsequent loss of weight of longan fruit during storage. However, the sulphite residues could detect immediately after SO2 treatment in all part of longan fruit, especially on aril tissue. The SEM evaluation found that the surface cracking was also impair the physiological function of the cuticle and increasing water permeability, which may cause water soaking at the inner side of the peel. The injured cell would accelerate the oxidation of phenolic substances and the oxidative products resulted in dark color of inner and outer peel.
对“Biew Kiew”品种龙眼果实进行了研究，将未处理（对照）和经二氧化硫处理的果实分别在2±2℃和7±2℃下储存0、2、4、6和8周。用二氧化硫熏蒸处理新鲜龙眼果实并结合适宜的储存条件，可提高龙眼果实的整体品质，尤其是在内果皮、外果皮组织和果肉颜色方面，比未进行二氧化硫处理的效果更好。该处理可稳定果皮颜色，在储存期间不会出现后续的颜色损失（果实颜色为亮淡黄色）。当果实进行二氧化硫处理时，随着储存时间和温度的增加，龙眼果实的内果皮和外果皮会出现深色，这与多酚氧化酶（PPO）活性的增加相关。对照果实（未进行二氧化硫处理）中PPO酶的活性逐渐低于二氧化硫处理的果实。与储存在较高温度（7℃）下的果实相比，暴露在低温储存温度（2℃）下的果实PPO酶活性较低。此外，PPO酶活性在储存期间显著增加。额外的二氧化硫处理使龙眼果实在储存期间没有后续的重量损失。然而，在二氧化硫处理后，可立即在龙眼果实的所有部位检测到亚硫酸盐残留，尤其是在果肉组织中。扫描电子显微镜评估发现，表面开裂也会损害角质层的生理功能并增加透水性，这可能导致果皮内侧出现水渍。受损细胞会加速酚类物质的氧化，氧化产物导致内果皮和外果皮颜色变深。
