The Study Of Controlled Atmosphere On Fresh-Keeping Effect And Physiological Mechanism Of Hongyang Kiwifruit And Mulberry In Postharvest

Kiwifruit and mulberry belong to berries, which have rich nutritions and distinct flavour, besides, which own high economic and medicinal value. However, there are short shelflife during storage under the normal tempreture. In order to investigate the effect of active controlled atmosphere on postharvest quality, softening and AsA-GSH cycle of Hongyang kiwifruit, which store at (1±0.5)℃,80%-95% relative humidity, and find out the suitable gas components dealing with fruits. Besides, we put mulberries (Morus indica L. Dianmian-1) as the experiment materials, which store at (5±1)℃,80%-90% relative humidity, aiming to study the influence of different packages on postharvest quality of mulberry, and find the material which is more suitable to use for mulberry storage.1. To investigate the influence of controlled atmosphere (CA) on storage life of postharvest Hongyang kiwifruit, sensory quality, starch, total soluble sugar (TSS), titritable acid (TA), chlorophyll and antioxidant activity were measured. Postharvest kiwifruits were stored under air (control) and air-O2-CO2 atmosphere (1±0.5℃,80%-95% relative humidity) with different gas compositions, i.e., CA1 (2% O2+3% CO2), CA2 (2% O2+6% CO2), CA3 (5% O2+3% CO2), and CA4 (5% O2+6% CO2). Results showed that there are significantly differences on storage life along different treatments, storage life of CK and CA4 treated are about only 60 d, CA2 treated up to about 90 d,2% O2+3% CO2 treated up to about 120 d, CA1-treated could siginificantly prolong storage life of fruits, especially. Suitable CA can delay fruits physiological metabolism through inhibting fruits respiration. CA could inhibiting the increase of ratio of TSS and TA, degration of chlorophyll, and maintain fruits antioxidant ability. Especially, CA1 (2% O2+3% CO2) treated could maintain fruits better sensory quality and antiocidant ability, and it is the most effective to improve storage quality.2. We evaluated the effects of controlled atmosphere on the content of pectin and the activities of relevant metabolizing enzymes (PE, PG, CX) of Hongyang kiwifruit. Postharvest kiwifruits were stored under air (control) and air-O2-CO2 atmosphere (1±0.5℃, 80%-98% relative humidity) with different gas compositions, i.e., CA1 (2% O2+3% CO2), CA2 (2% O2+6% CO2), CA3 (5% O2+3% CO2), and CA4 (5% O2+6% CO2). Result showed that PG and CX had the sinificant relation with fruit softens, but PE did not have. CA could delay decreasing of fruits firmness and decomposition of pectin through delaying the increase of PG and CX activity, but CA has little effect on PE activity. Compared with CK, CA1 (2% O2+3% CO2) is the most effective to maintain fruits firmness.3. We evaluated the effects of controlled atmosphere on AsA-GSH of Hongyang kiwifruit. Postharvest kiwifruits were stored under air (control) and air-O2-CO2 atmosphere (1±0.5℃,80%-98% relative humidity) with different gas compositions, i.e., CA1 (2% O2+ 3% CO2), CA2 (2% O2+6% CO2), CA3 (5% O2+3% CO2), and CA4 (5% O2+6% CO2). Results showed that CA1 (2% O2+3% CO2) treated could maintain the activity of APX, DHAR, MDHAR and GR, and higher content of AsA, DHA, GSH and GSSG of fruits, which could enhance fruits antioxidanst system and cell defense capabilities. This study expained that CA1 treated had the positive effect on the storage of postharvest kiwifruit from the perspective of AsA-GSH circle.4. To investigate the influence of films packaging with different thickness on postharvest quality of mulberry, in this experiment, mulberries (Morus indica L. Dianmian-1) were treated by five film packages (5.40 μm polyethylene bag P1,12.75μm polyethylene bag P2,15.55μm polyethylene bag P3,32.70μm polyethylene bag P4,15.55 μm polyethylene bag with four holes CK) at (5±1)℃ 80%-90% relative humidity. The results showed that all packages could decrease fruit decay indexes in comparison to CK, inhibiting fruits respiration rate, delaying increase of ratio of TSS and TA, maintaining higher antioxidant ability. It was thus clear that this effect of packages on mulberry quality has relation with its high concentration CO2 and low concentration O2. P4 treatment could maintain significant higher concentration CO2 (5.90%-6.90%) and lower concentration O2 (6.20%～8.50%) compared with CK and other treatments, besides, which maintain higher antioxidants ability, and had the positive effect on mulberry during storage.Above all, in order to prolong fruits storage and shelflife, we can adjust concentration of CO2 and O2 to regulate the physiological metabolism of Hongyang kiwifruit and mulberry.