《食品工业科技》F5000论文展播：气调贮藏对“徐香”猕猴桃采后保鲜效果影响

目的：“徐香”猕猴桃果实采后易失水萎缩、软化腐烂、品质下降，造成了果实销售期短暂而相对集中，难以保证长期市场供应。本文通过研究不同成分气体处理对采后猕猴桃果实生理品质和营养品质的影响，从而确定最佳的适宜猕猴桃贮藏保鲜的气调条件，以期为气调保鲜应用于猕猴桃长期贮藏提供理论与实践依据。

方法：将在温度为(4 ± 1) ℃，相对湿度为85% ± 5%的条件下充分预冷24 h后的“徐香”猕猴桃随机分成5组，分别贮藏于气体成分为2%O₂+ 3%CO₂、2%O₂+ 5%CO₂、5%O₂+ 3%CO₂、   5% O₂+ 5%CO₂的气调箱内，以空气作为对照组。每隔10 d取样一次，每次分别从各组中随机取15个猕猴桃，使用硬度计测定其各部位的硬度，使用数字折光仪测量其总可溶性固形物含量，采用2，6－二氯酚靛酚滴定法测定其维生素C（V_C）含量，采用福林－酚比色法测定其总酚含量，采用硫代巴比妥酸比色法测定其丙二醛含量，采用愈创木酚法测定其过氧化物酶(peroxidase，POD)活性，采用邻苯二酚比色法测定其多酚氧化酶（peroxidase，PPO）活性，以上各指标均取3个平行样，重复3次，然后计算其均值，并运用Excel 2007和Origin 8.0软件对数据进行处理分析。

结果：通过测定贮藏期间“徐香”猕猴桃果实的各项生理指标发现，气体成分为2%O₂+ 3%CO₂时，猕猴桃果实随着贮藏期的延长，衰老程度比较严重；气体成分为5%O₂+ 3%CO₂、5%O₂+ 5%CO₂以及2% O₂+ 5% CO₂时，贮藏期间，猕猴桃果实能得到较好的保鲜效果，其中2%O₂+ 5%CO₂的气调条件对猕猴桃的保鲜效果最好，能够较好地保持果实品质。贮藏末期，2%O₂+ 5%CO₂组的硬度最高，而对照组的猕猴桃果实几乎完全软化；2%O₂ + 5%CO₂组的可溶性固形物含量显著高于其他各组(P＜0.05)，为10.5%；2%O₂+ 5%CO₂组的V_C含量为218.41 mg/100 g，显著高于对照组(P＜0.05)，有效减缓了V_C的分解速度；2%O₂+ 5%CO₂组总酚含量的下降速度最为缓慢，是对照组的1.8 倍；2%O₂+ 5%CO₂气体成分贮藏的猕猴桃丙二醛含量仅为0.047 μmol/g·Fw，显著低于其他处理组(P＜0.05)，可有效降低猕猴桃果实中丙二醛的积累，降低了果实的膜脂过氧化程度；2%O₂+ 5%CO₂组的POD活性稳居首位，POD值显著高于其他各组(P＜0.05)；且2%O₂+ 5%CO₂组PPO的活性处于最低水平，PPO的活性值显著低于其他各组(P＜0.05)，有效减缓了猕猴桃果实的褐变速度。

结论：2%O₂+ 5%CO₂的气调贮藏条件对“徐香”猕猴桃果实的保鲜效果最好，贮藏期间，可有效保持果实的硬度，延缓可溶性固形物含量、V_C含量、总酚含量的下降，抑制POD活性下降，维持较低的PPO活性和丙二醛含量，促使果实组织抗氧化系统保持完善，延缓果实的衰老速度，保持果实的最佳品质，延长果实市场供应期。此研究在猕猴桃果实的贮藏保鲜方面具有良好的应用前景。

Objectives: "Xuxiang" kiwifruit is easy to lose waterand shrink, soften and rot, quality decline after harvest, which create short and relative concentration of fruit sales period, and it is difficult to guarantee long-term supplyof market. This article aimed to study the physiological and nutritional quality of postharvest kiwifruit treated by different componentsgas, so as to determine the best atmosphere storage conditions suitable for kiwifruit storage and preservation, in order to provide a theoretical and practical basis for the application of modified atmosphere preservation in long-term storage of kiwifruit.

Methods: The "Xuxiang" kiwifruit after fully precooling for 24 h at (4±1) ℃and a relative humidity of(85%±5%)were randomly divided into 5 groups, and stored in the controlled atmosphere chamber with gas components of 2%O₂+ 3%CO₂, 2%O₂+ 5%CO₂, 5%O₂+ 3%CO₂ and 5%O₂+ 5%CO₂, the air was used as the control group. Fifteen kiwifruit were randomly selected from each group every 10 days, the hardness of each part wasmeasured by a hardness tester, the total soluble solid contentswas measured by digital refractometer. The vitamin C (V_C) contents was determined by 2,6-dichlorophenol indophenol titration, the total phenol content was determined by Folin phenol colorimetry, the malondialdehyde (MDA) contentswas determined by thiobarbituric acid colorimetry, the peroxidase (POD) activity was determined by guaiacol method, the polyphenol oxidase (PPO) activity was determined by catechol colorimetry. Three parallel samples were taken for all indicators, repeated for 3 times, then calculated their mean value, the data were processed and analyzed by Excel 2007 and origin 8.0 software.

Results: By measuring the physiological indexes of "Xuxiang" kiwifruit during storage, it was found that when the gas composition was 2%O₂+ 3%CO₂, the aging degree of kiwifruit was more serious with the extension of storage period. When the gas composition was 5%O₂+ 3%CO₂,  5%O₂+ 5%CO₂ and 2%O₂+ 5%CO₂, kiwifruit could get better fresh-keeping effect during storage,the best atmosphere storage conditions of 2%O₂+ 5%CO₂ had the best fresh-keeping effect on kiwifruit, the fruit quality could be well maintained. At the end ofstorage, the hardness of 2%O₂+ 5%CO₂ group was the highest, while the kiwifruit of control group almost completely softened. The soluble solids contents of 2%O₂+ 5%CO₂ group was significantly higher than that of other groups (P<0.05), which was 10.5%. The V_C contents of 2%O₂+ 5%CO₂ group was significantly higher than thatof control group (P<0.05), which was 218.41 mg/100 gand slowed down the decomposition speed of V_C effectively. The decrease rate of total phenol contents of 2%O₂+ 5%CO₂ group was the slowest, which was 1.8 times higher than thatof control group. The MDA contents in kiwifruit stored with 2%O₂+ 5%CO₂ was significantly lower than that of other treatment groups (P<0.05), which wasjust 0.047 μmol/g·Fw, which could effectively reduce the accumulation of MDA in kiwifruitand the degree of membrane lipid peroxidation was reduced. The POD activity of 2%O₂+ 5%CO₂ group ranked first,the value of POD was significantly higher than that of other groups (P<0.05). The PPO activity of 2%O₂+ 5%CO₂ group was the lowest, the value of PPO was significantly lower than that of other groups (P<0.05), the browning rate of fruit was slowed down effectively.

Conclusions: The controlled atmosphere storage condition of 2%O₂+ 5%CO₂ has the best fresh-keeping effect on "Xuxiang" kiwifruit. During storage, it can effectively maintain the hardness of kiwifruit, delay the decline of soluble solids content, V_C content and total phenol contents, inhibit the decline of POD activity, maintain low PPO activity and MDA content, promote the antioxidant system of fruit tissue to remain perfect, delay the senescence rate of fruit, maintain the best quality of fruit and prolong the supply period of fruit market. This study have a good application prospect in the storage and preservation of kiwifruit.