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性的关系，结果表明：青花菜花的衰老与维生素C含量的降低密切相关，乙烯产生量随衰老的增加而增加，青花菜花的衰老表现为气体诱导的衰老。NAD^+/NADH和NADP^+/NADPH的比值反映了氧化还原电位的变化，并随熟化程度的变化而变化。AMP、ADP、ATP和能荷的变化很小，不符合易腐作物新鲜度的评价。某些作物的膳食纤维含量在贮藏过程中基本保持不变，可以用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。这些指标中的两个或三个的复合可能对评价水果和蔬菜的新鲜度有效。

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.