Evaluation of freshness of fruits and vegetables in relation to their Metabolic Activities

研究了果蔬新鲜度评价与其代谢活动的关系。青花菜的衰老与维生素C含量降低有很高的相关性，乙烯释放量随果蔬脱脂而增加，气体诱导青花菜的衰老表现为青花菜的脱脂。指示氧化还原电位的NAD^+/NADH和NADP^+/NADPH比值随温度升高而变化。AMP、ADP、ATP和能荷的变化很小，不能满足易腐烂作物的新鲜度评价。部分农作物在贮藏过程中膳食纤维含量基本不变，可通过叶绿素和类胡萝卜素含量、蔗糖合成相关酶活性、氧化还原系统、膜系统和细胞壁合成等指标来评价其新鲜度。综合上述两个或三个指标，可有效地评价水果和蔬菜的新鲜度。

The present study was carried out to investigate the relationship between the evaluation of freshness of fruits and vegetables and their metabolic activities.There was a high correlation between the dagreening and the reduction of vitamin C content in broccoli floret, and the ethylene production increased with degreening and the gas induced the senescence shown as degreening of broccoli. The ratios of NAD^+/NADH and NADP^+/NADPH, indicating redox potential, changed with degreening. Changes in AMP,ADP,ATP and energy charge were very small so that it did not meet the evaluation of freshness of perishable crops. The dietary fiber content of some crops was almost constant during storage.The freshness was considered to be evaluated by using indices such as contents of chlorophyll and carotenoids, enzymes activities related to sucrose synthesis, redox systems, membrane system and cell wall synthesis. The complexing of two or three of these indices may be effective to evaluating the freshness of fruits and vegetables.