涂膜和热处理对葡萄能量和贮藏生理及品质的影响

摘要

研究不同处理对欧亚种“维多利亚”葡萄组织能量水平和生理品质的影响。采后葡萄经钙联合涂膜和热处理，即在质量分数为0.2%CaCl2和1%壳聚糖中浸泡20 min，45℃的0.2%CaCl2溶液中浸泡20 min，晾干后(4±0.5)℃贮藏，每10 d测定果实的呼吸强度、褐变指数（browning index，BI）、腐烂率、硬度、丙二醛（malondialdehyde，MDA）含量、三磷酸腺苷（adenosine triphosphate，ATP）、二磷酸腺苷（adenosine diphosphate，ADP）、单磷酸腺苷（adenosine monophosphate， AMP）的含量，多酚氧化酶（polyphenol oxidase，PPO）、过氧化物酶（peroxidase，POD）、脂氧合酶（lipoxygenase， LOX）和超氧化物歧化酶（soperoxide dismutase，SOD）活性变化，以未处理为对照。结果显示对照组葡萄组织中能量物质处于亏损状态，呼吸强度减弱，细胞膜氧化增加，膜透性、BI、腐烂率增加，PPO、POD和LOX活性增加，SOD降低，果实软化。钙联合热和涂膜处理较好维持了果实的能量水平和生理品质，且涂膜优于热处理。ATP与硬度、SOD显著正相关（r=0.938，0.930，P<0.01），与MDA、膜透性、LOX显著负相关（r=−0.896，−0.932，−0.940，P<0.01）；能荷（energy charge，EC）值与膜透性、LOX负相关（P<0.05），与呼吸强度和SOD活性正相关（P<0.05）。随贮藏时间的延长，葡萄组织的能量水平处于亏损状态，能量水平显著影响生理品质。经适当的采后处理可延缓能量亏损，涂膜优于热处理。%Harvested grape fruit tissues are still alive. Grape fruit tissues still have metabolism including physiological and biochemical reactions. They are prone to physiological deterioration, such as texture softening, browning, decay and mildew. More and more studies have indicated that senescence and cell membrane permeability of horticultural crops may be related to energy deficit caused by the decline of energy synthesis. Changes of energy levels in grape fruit tissues during storage have not been reported. Effects of energy level on physiological quality of grape fruit tissues after coating and heat treatment with Ca2+ are not clear. In this paper, the effects of coating and heat treatments with Ca2+ on post-harvest energy levels and physiological deterioration of “Victoria” grape fruit during cold storage were explored through determining energy levels and physiological indices. Coating and heat treatments with Ca2+ were applied to post-harvest grape fruits (compared with untreated grape fruits, i.e. the CK treatment). Grape fruits after coating and heat treatments with Ca2+were stored at (4±0.5)℃. Respiratory rate, browning index, decay rate, hardness, contents of malondialdehyde (MDA), adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP), energy charge (EC), and enzyme activities of polyphenol oxidase (PPO), peroxidase (POD), lipoxygenase (LOX) and soperoxide dismutase (SOD) of grape fruits were tested every 10 days. Results showed that with the extension of storage time, energy levels were in a loss state for grape fruit tissue under the CK. Respiratory rate decreased, but cell membrane oxidation and permeability increased. Browning index and decay rate increased, and enzyme activities of POD, PPO and LOX increased too, but enzyme activities of SOD were decreased. Physiological qualities of grape fruits decreased, and fruits were softened. Calcium combined with heat and coating treatment reduced the loss of grape fruits by rotting during storage. In addition, treatment of heat and coating with Ca2+ could maintain higher energy status, energy charge, hardness and enzyme activities of SOD to keep qualities of grape fruit, delay grape fruit softening, inhibit respiratory intensity and accumulation of membrane lipid peroxidation, slow down growth of cell membrane permeability, decrease MDA content, inhibit enzyme activities of POD, PPO and LOX, and delay browning and rotting, aging process and physiological quality deterioration of grape fruits. But coating treatment was better than heat treatment. ATP was significantly positive correlation with hardness and SOD enzyme activity (r=0.938,0.930,P<0.01), but negative correlation with MDA membrane permeability and LOX enzyme activity (r=-0.896,-0.932,-0.940,P<0.01). EC was negative correlation with membrane permeability and LOX enzyme activity (P<0.05), but positive correlation with respiration intensity and SOD enzyme activity (P<0.05). Browning of grape fruits was closely related to membrane lipid peroxidation and membrane structure (the integrity of membrane structure was destroyed). PPO and POD were reacted with phenolic substrates to form brown pigment. Results showed that with the extension of storage time, energy levels of grape fruits were in a loss state. Fall of energy level significantly affected oxidation and integrity of cell membrane. Coating and heat treatments with Ca2+ could maintain higher energy levels of ATP and ADP, and EC, which could slow down aging and physiological quality deterioration of grape fruit tissues. Coating and heat treatments with Ca2+ may maintain high energy status and physiological qualities, and slow down aging and physiological quality deterioration of grape fruits tissues. Effects of coating treatment with Ca2+ were better than heat treatment with Ca2+. Slowing down physiological deterioration of grape fruits can be realized by maintaining high energy status and preventing development of physiological deterioration.