采后预冷及气调贮藏对荔枝γ-氨基丁酸富集及贮藏品质的影响

本研究以‘怀枝’荔枝为试材,探究了采后预冷及CO_2气调贮藏对果实γ-氨基丁酸(γ-aminobutyric acid,GABA)富集的影响,并比较了贮藏期间荔枝质构、色差、感官品质等指标的变化。结果表明:从荔枝GABA富集和贮藏品质来看,冰水预冷的效果均优于冷库预冷;荔枝CO_2气调贮藏的GABA含量呈先上升后下降趋势,且更高体积分数的CO_2气调贮藏组具有更高的GABA富集量,最高达19.97 mmol/kg mf,较气调贮藏前提高了40%;GABA含量与谷氨酸脱羧酶(glutamate decarboxylase,GAD)活力变化趋势相同,与γ-氨基丁酸转氨酶(γ-aminobutyric acid transaminase,GABA-T)活力变化趋势无相关性,表明荔枝GABA富集主要是由于GAD活力的增强催化了GABA的生成,而非GABA-T活力的下降抑制了GABA的分解;CO_2气调贮藏能够抑制荔枝果肉的软化,延缓荔枝感官品质、果皮果肉色差值的下降;过高的CO_2气调体积分数可能会引起荔枝的CO_2损伤,使其迅速丧失商品价值。

Impact of Postharvest Precooling and Controlled Atmosphere Storage on γ-Aminobutyric Acid (GABA) Accumulation and Storage Quality in Litchi (Litchi chinensis Sonn.) Fruits

The objective of the present study was to analyze γ-aminobutyric acid (GABA) accumulation associated with postharvest precooling and controlled-atmosphere storage as indicated by GABA metabolism in litchi (Litchi chinensis Sonn. cv. ‘Huaizhi’) fruits. In addition, changes in fruit firmness, color and sensory quality were monitored during storage. The results showed that iced water precooling was better than room precooling for GABA accumulation and storage quality. GABA concentration increased first and then decreased during high-CO2 controlled-atmosphere storage, and the peak concentration (19.97 mmol/kg mf) was 1.4 times as high as that at harvest. There was a positive correlation between GABA concentration and glutamate decarboxylase (GAD) activity, while there was no correlation between GABA concentration and GABA transaminase (GABA-T) activity, indicating that GABA accumulation was mainly due to the enhanced GAD activity, promoting the synthesis of GABA, rather than the decreased GABA-T activity, inhibiting the catabolism of GABA. Pulp firmness, pericarp color and sensory quality of the controlled-atmosphere stored litchi fruits were significantly better than those of the fruits stored under normal atmosphere. Litchi fruits showed serious injury and promptly lost commodity value during excessive CO2 controlled-atmosphere storage.