Study on the mechanism of browning of pomegranate peel in different storage conditions

Chinese. 研究石榴贮期果皮褐变机理，探讨防褐变技术。以采后陕西临潼净皮甜石榴为试材，研究了贮藏温度、气体成分和pH对果皮褐变的作用，测定了引起果皮褐变的主要物质单宁的变化规律，分析了抗坏血酸氧化酶（AAO）、多酚氧化酶（PPO）、过氧化物酶（POD）和过氧化氢酶（CAT）的活性与果皮褐变的关系。单宁是石榴果皮褐变的底物；AAO、PPO、POD活性与果皮褐变指数呈正相关性，CAT活性与果皮褐变指数呈负相关性。石榴在pH 4.0、（5.0±0.5）℃、5.0% CO2+8.0%O2+87.0%N2的气体成分条件下贮藏，每隔5 d在（15±0.5）℃下间歇升温处理24 h，贮藏120 d褐变指数仅为0.15。石榴贮期酶促单宁变性是果皮褐变的主要原因，在适宜的pH、贮藏温度和气体成分条件下间歇升温贮藏，防褐变效果理想。

English. Peel browning of pomegranate fruit is the key problem during storage. The mechanism of pomegranate peel browning during storage, in relation to the technology of the browning control was studied. The effects of storage temperature, gas component and pH value on peel browning of Shaanxi Lintong sweet pomegranate fruit were investigated. Change in tannin content was measured while the relationship between the activities of ascorbic acid oxidase (AAO), polypenoloxidase (PPO), peroxidase (POD), catalase (CAT) and peel browning were analyzed. Tannin was the basic substance of pomegranate peel browning. The activities of the browning index of peel were correlated positively with AAO, PPO and POD, correlated negatively CAT activity. Application of intermittent warming of 24 h at (15±0.5)℃ every 5 days to Pomegranate fruit stored under the conditions of pH 4.0, (5.0±0.5)℃ and 5.0%CO2+8.0%O2+87.0%N2 gas component delayed browning, with the browning index being 0.15 after 120 days of storage. Enzymatic tannin denaturation was the main cause that led to peel browning of pomegranate fruit during storage. The browning control of pomegranate fruit peel was effective using intermittent warming storage with suitable pH, temperature and gas component.