Studies On Mechanism Of Inducing Chilling Tolerance By Heat Shock Treatment In Cucumber

This study used’Jintian 208’cucumber as test materials to reveal the physiological characteristics. By comparing the different effect of storage, to determine the inhibition effect of heat shock treatment. In order to investigate the mechanism of inducing chilling tolerance by heat shock treatment, the experiment observed physiological changes and storage characteristics, studied the metabolization of active oxygen and lipid peroxidation, measured the changes of cell wall components and amino acids contents. In addition, the structure features and volatile components were also studied.1. The appropriate cucumber heat shock treatment conditions were determined. Hot water and hot air heat shock treatment can both reduce the effect of the impact on the chilling injury. Inappropriate heat treatment may cause mildew, filtration, fading green and hot spots.42 ℃,10 min hot water treatment could significantly reduce the cucumber chilling injury index.At the end of the storage, the Vc content, chlorophyll content, soluble protein content is 15.5%,86.5%,and 80.4%higher than the control group, respectively. It also maintain the lower malondialdehyde (MDA) content and relative conductivity, played a great effect on reducing cucumber chilling injury symptoms. The results suggested that such a treatment is an appropriate method for cucumber to prevent it from chilling injury.2. It was heat shock treatment that stimulated the increment of H2O2, the content of 3d surged to twice of its original value.The results indicated that heat shock treatment enhanced the activities of SOD, CAT and POD, and enhanced the capacity of scavenging free radical. Except Od, the O2- generation rate of heat shock group were significantly higher than the control. At the same time,the H2O2 accumulation were inhibited, and the membrane lipid peroxidation were reduced.So the chilling injury index is reduced from 33.2% to 11.8%.3. At the same time, it can restrain enzyme activity of the cell walls such as PG and Cx, so it can maintain the integrity of cells better than CK.4. Heat shock treatment can make the free amino acid composition increased, it also can promote the rise of proline content. Heat shock treatment can make glutamic acid content increased, at the end of the storage was 53.5% higher than the control group. There is also a relationship between the proline, aspartic acid, glutamic acid, serine, alanine and chilling injury.5. The analysis of textural properties and aroma components revealed that:heat shock treatment can slow the decrease of fruit firmness, cohesiveness, chewiness and other parameters. Heat shock treatment can effectively delay the increase of (E,Z)-2,6-Nonadienal and the reduction of E-2-nonenal,and also have effect on delaying aroma desalination by reducing the changes of components like (+)-(4R)-Limonene、Myrcen、1-Caryophyllene.