N_2预处理结合MAP复合保鲜处理对水蜜桃贮藏品质、活性氧代谢及能量状态的影响

Effect of Short-term Nitrogen( N_2) Pre-treatment in Combination with the Modified Atmosphere Package( MAP) on the Nutritional Quality,Reactive Oxygen Metabolism and Energy Status of Harvested Honey Peach Fruits

【目的】水蜜桃采收后易后熟和衰老,贮藏期和货架期短。本研究为寻求安全有效的水蜜桃贮藏保鲜方式,并探究其保鲜机理。【方法】以＂湖景蜜露＂水蜜桃为试材,研究氮气预处理结合自发气调（MAP）复合保鲜处理对果实低温贮藏及货架期间营养品质、活性氧代谢及能量水平的影响。果实经100%N2处理6 h后,用厚度0.02 mm的聚乙烯薄膜袋密封包装,对照组不做任何处理。所有果实均置于（1±1）℃相对湿度85%-90%保鲜库中,贮藏30天后,从薄膜袋取出,置于（25±1）℃下模拟货架期。测定低温贮藏及货架期间水蜜桃果实腐烂指数、硬度、可溶性固形物（TSS）、维生素C（Vc）和过氧化氢（H2O2）含量、超氧阴离子（O2·^-）产生速率、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和脂氧合酶（LOX）活性、膜透性、丙二醛（MDA）含量、腺苷三磷酸（ATP）、腺苷二磷酸（ADP）和腺苷磷酸（AMP）含量及能荷（EC）值。【结果】结果表明：随着冷藏及常温货架存放时间的延长,对照组水蜜桃果实组织中的ATP,ADP含量和能荷低温贮藏10天后即开始出现明显降低,SOD和CAT在整个贮藏过程中均呈现明显的下降趋势,H2O2和O2·^-的含量明显增加,而MDA含量与膜透性则呈大幅度的上升,导致膜脂过氧化程度的增加和膜完整性的破坏。N2预处理结合MAP复合保鲜处理可有效降低水蜜桃果实低温贮藏过程中的腐烂指数,当果实转到25℃放置4天,处理组水蜜桃的果实腐烂指数仅为对照组果实的55.56%。同时,N2预处理结合MAP复合保鲜处理能有效地维持果实TSS及Vc含量,较好保持了营养品质。进一步研究发现,N2预处理结合MAP复合保鲜处理能维持果实中较高的ATP,ADP含量及能荷值,提高SOD及CAT活性,进而抑制H2O2积累及O2·^-的产生,降低MDA含量及膜透性的升高。相关性分析表明,在贮藏过程中,能荷值与O2·^-产生速度（R^2=0.9712）、H2O2含量（R2=0.9746）及膜透性（R^2=0.9678）具有显著负相关性。【结论】N2预处理结合MAP复合保鲜处理延缓水蜜桃后熟衰老可能与提高果实组织能量水平及抗氧化水平,维持活性氧代谢的平衡,保持膜的完整性有关。

【Objective】Honey peach（ Prunus persica） fruits are highly perishable and rapidly lose quality after harvest.To explore an effective and safe storage technique and the preservation mechanism of the fruits,the effect of short-term N2 treatment in combination with the modified atmosphere package（ MAP） on overall quality,reactive oxygen species（ ROS）metabolism and energy level in honey peach fruits（ cv. Hujingmilu） during storage were investigated. 【Method】Honey peach fruits were pretreated with pure N2 for 6 h in glass jars,and packaged with 0. 02 mm polyethylene film. Fruits without any treatment were used as control. All fruits were stored for 30 days at（ 1 ± 1） ℃ and at 85% - 90% relative humidity and subjected to subsequent shelf life at（ 25 ± 1） ℃. The decay index solidity,content of total soluble solids（ TSS）,ascorbic acid（ Vc） and H2O2,superoxide anion（ O2·^-） production rate,activities of superoxide dismutase（ SOD）,catalase（ CAT） and lipoxygenase（ LOX）,membrane permeability,malondialdehyde（ MDA） content,contents of adenosine triphosphate（ ATP）,adenosine diphosphate（ ADP） and adenosine monophosphate（ AMP） and energy charge（ EC） were analyzed during the cold storage and shelf life. 【Result】Results indicated that contents of ATP and ADP in the control fruit decreased rapidly in 10 days of cold storage. Both SOD and CAT activity were observed to have a decrease during the whole cold storage and subsequent ripening of the control fruits while th O2·^- production rate,H2O2 content and MDA content increased significantly,leading to increase in membrane lipid peroxidation level and the damage degree of the membrane integrity. Compared with the control,short-term N2 treatment in combination with MAP treatments effectively reduced decay index as evidence in showing that the decay index was only 55. 56% of the control on day 4 of shelf life. Furthermore,the application of short-term N2 treatment in combination with MAP effectively increased contents of ATP and ADP content and EC value,enhanced activities of CAT and SOD,delayed increases in both O2·^- production rate and H2O2 content and reduced MDA content and membrane permeability. Thus the treatments maintained the nutritional quality during low temperature storage and subsequent shelf life at room temperature. Correlation analysis showed that EC value was very significantly negatively correlated with O2·^-production rate（ R^2= 0. 971 2）,H2O2content（ R^2= 0. 974 6） and membrane permeability（ R^2= 0. 967 8）. These results suggested that short-term N2 treatment in combination with MAP treatments maintained high energy level and antioxidant levels,delayed the accumulation of ROS and alleviated the process of membrane lipid peroxidation,thereby delaying the ripening and senescence and maintaining the quality of honey peach. 【Conclusion】 Thus,the extension of shelf life of honey peach by short-term N2 treatment in combination with MAP might be due to the improvement of energy status and antioxidant properties,and alleviation of membrane damage.