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以“红富士”苹果为试材,在(0±1)℃贮藏条件下,分别采用聚氯乙烯袋(PVC,厚度为0.03mm)包装处理(MAP)和不包装处理(对照),研究MAP对苹果果皮色素花青苷、叶绿素、类胡萝素含量及色泽指标(果皮光泽的明亮度、果皮色泽比)的影响,以及花青苷含量变化与其合成相关酶[苯丙氨酸解氨酶(PAL)、查尔酮异构酶(CHI)、二氢黄酮醇还原酶(DFR)、类黄酮-3-O-葡萄糖基转移酶(UFGT)]及降解相关酶[多酚氧化酶(PPO)、过氧化物酶(POD)]活性的变化。结果表明:与对照相比,MAP抑制贮藏期间叶绿素降解及贮藏前期花青苷的积累,延缓类胡萝素的积累及花青苷的后期降解;延缓果实色泽亮度L*及色泽比a*/b*的下降;贮藏期间花青苷的合成与PAL、UFGT活性变化有关,与CHI、DFR活性变化不相关;贮藏期间花青苷降解相关酶PPO、POD活性都呈现先上升后下降的趋势,MAP抑制果皮PPO活性的升高,MAP明显抑制贮藏前期果皮POD活性的上升及贮藏后期POD活性的下降。在采后贮藏过程中,自发气调包装(MAP)有利于延缓“红富士”苹果果皮底色黄化和红色色素的降解,可较好地保持外观品质。
Using “Red Fuji” apple as test material, PVC (0.03mm thickness) packaging (MAP) and no packaging (control) were respectively stored under (0 ± 1) The effects of MAP on the contents of anthocyanin, chlorophyll and carotenoid in apple peel pigment and the color index (the brightness of peel and the color ratio of peel) were studied. The changes of anthocyanin content and the enzyme related to its synthesis [phenylalanine (PAL), chalcone isomerase (CHI), dihydroflavonol reductase (DFR), flavonoid-3-O-glucosyltransferase (UFGT) and degradation related enzymes [polyphenol oxidase (PPO), peroxidase (POD)] activity. The results showed that MAP inhibited the chlorophyll degradation during storage and the accumulation of anthocyanins during storage, delayed the accumulation of carotenoids and the post-degradation of anthocyanins. Compared with the control, MAP delayed the fruit color brightness L * and the color ratio a * b * decreased. The anthocyanin synthesis during storage was related to PAL and UFGT activities, but not to changes in CHI and DFR activities. The activities of PPO and POD in the anthocyanins degraded during storage increased firstly and then decreased, MAP inhibited the PPO activity in the pericarp. MAP significantly inhibited the increase of POD activity in the pericarp and the decrease of POD activity in the late storage stage. During postharvest storage, spontaneous modified atmosphere packaging (MAP) is conducive to retarding the yellowing and red pigment degradation of “Red Fuji” apple peel, which can better maintain the appearance quality.