热水处理对金柑果实采后腐烂及生理特性的影响

Effects of hot water treatment on postharvest rot and physiological characteristics of kumquat fruits

关键词:  热水处理, 金柑, 品质, 腐烂率, 抗氧化物酶

Key words:  hot water treatment, kumquat, rotting rate, quality,defense enzyme

摘要:

金柑是果皮和果肉同食的柑果类型,对采后处理要求极为严格。该研究以金柑(Fortunella crassifolia)为材料,研究了其经30、40和50 ℃热水浸泡后果实的腐烂率、失重率、可溶性固形物、硬度、有机酸、细胞渗透率以及抗氧化酶活性变化。结果表明:经30 ℃热水处理5 min的果实失重率高于对照,而经40 ℃和50 ℃处理的果实失重率低于对照或差异不显著。经热水处理的果实总酸含量略低于对照,可溶性固形物含量在18%上下波动且差异不显著。热水处理可提高果实硬度,降低贮藏前期果实细胞渗透率以及贮藏过程中果实过氧化物酶和超氧化物歧化酶活性,激发过氧化氢含量升高,可有效降低贮藏过程中金柑果实腐烂率,但不同采收期的金柑所需的热水处理温度和时间不同。对于1月初采收的果实,处理时间为5 min或10 min可降低果实腐烂率; 2月初采收的果实,40 ℃或50 ℃热水处理10 min可有效降低果实腐烂率; 3月初采收的果实,当处理温度达到50 ℃,处理时间达到10 min,才可有效降低果实腐烂率,且对果实品质没有明显的不利影响。

Abstract:

Kumquat was the type of tangerine fruit with the skin and pulp both edible, therefore the processing requirements for the postharvest treatments are extremely strict. The present research treated kumquat(Fortunella crassifolia)with hot water using three temperature gradient, 30, 40 and 50 ℃, respectively. The fruit rotting rate, weight loss rate, soluble solids, hardness, organic acid, cell permeability and the changes of antioxidant enzyme activity were investigated. The results showed that the total acid content was maintained at 0.3% during the storage process. After hot water treatment, the total acid content was slightly lower than that of the control, and the soluble solids content was around 18% and not significant compared to the control. The hardness of the treated fruits was first decreased and then increased during storage, but the hardness of the heat-treated fruit was higher than that of the control group during the whole storage. The leakage rate of cell membrane first increased and then decreased, and the hot water treatment could delay the peak time. The fruits CAT activity of the 40 ℃ and 50 ℃ hot water treatment were lower than that of the control. During the whole storage period, the fruits POD activity was lower than that of the control after hot water treatment. Hot water treatment could increase the kumquat fruit SOD activity, and with the increase of storage temperature, the effect was enhanced. Hot water treatment could increase the H₂O₂ content of the fruit and thus induce a series of physiological effects. However, the temperature and the duration of hot water treatment should be correspondingly adjusted. This study showed that, for the fruit harvested in March, if the hot water was higher than 40 ℃, the processing time should be longer than 5 min, which could effectively reduce the rate of fruit decay.