| Hami melon(Cucumis melo var.Saccharinus)is a characteristic agricultural product in Xinjiang.It is popular with consumers because of its sweet and delicious,crisp and juicy.Its main sales for Beijing,Shanghai and so on.And the transport process of the reverse environment will accelerate the aging of Hami melon,increase its decay rate,thereby reducing the shelf life of Hami melon,resulting in economic losses.The vibration in transportation will cause mechanical damage to the melon,accelerate its softening and even cause deterioration of quality and other serious consequences,it is through the simulation of transport vibration,the study of vibration on the quality of Hami melon storage quality is necessary.This paper mainly studies the influence mechanism of different grade roads(highways,arterial roads(ARs),secondary roads(SRs)and tertiary roads(TRs))on the quality of the melon during the storage process,and the establishment of the shelf life prediction model.The mainly researching contents and results were listed as follows:1.In order to study the Effect of different levels of road transport vibration on Hami melons active oxygen metabolism and membrane lipid oxidation,the vibration environment of the semi-trailer in highways,ARs,SRs and TRs were simulated.Relative electric conductivity,Lipoxygenase(LOX),malondialdehyde(MDA)and reactive oxygen species(ROS)with different road vibration treatments and without vibration during storage(28 d)at room temperature(23 ℃)were compared.The results showed that the electric conductivity of Hami melon with different road vibration was significantly higher than that of the control group after 28 days of storage,the content of MDA was also increased,the peak of lipoxygenase was advanced and the generation of reactive oxygen was also more obvious,and the influence of cell membrane on tertiary road and secondary road is more obvious than that on highway.The results indicated that the vibration accelerated the membrane lipid oxidation during the storage of Hami melon and destroyed the membrane integrity.Finally accelerated the senescence and decay of Hami melon.2.The effect of transportation on different roads on the antioxidant system of Hami melon is different.The transportation vibration environment of the semi-trailer in highways,ARs,SRs,and TRs were simulated in this experiment.The respiration rate,decay index,contents of total phenolics,VC,ascorbate peroxidase(APX),superoxide dismutase(SOD),catalase(CAT),Peroxidase(POD)and the total antioxidant capacity of different road vibration treatments and without vibration during storage at room temperature(23 ℃)for 28 d were compared.The results showed that the six indexes of Hami melon under different grades of road vibration were all lower than those of the control group at 28 days of storage,and the damage to the antioxidation system of Hami melon was more serious in the SRs and the TRs than on the highways and the ARs(P <0.05),which indicated that the vibration will reduce the activity of various enzymes and anti-oxidants in the antioxidant protection system during the storage of Hami melon,so as to accelerate cell membrane lipid oxidation,damage integrity of cell membrane,and finally accelerate the senescence and corruption of the melons,the transportation vibration of SRs and TRs is more obvious.3.In order to study the effect of vibration on the cell wall of Hami melons in different grade road during storage.The effect of semi-trailer on highway,ARs,SRs,and TRs were simulated,and the hardness,water-soluble pectin,CDTA-soluble pectin,sodium carbonated-soluble pectin,polygalacturonic acid enzyme(PG)and pectin esterase(PE)with different road vibration treatments and without vibration during storage(28 d)at room temperature(23 ℃)were compared.The results showed that the hardness,covalent pectin and ion-bound pectin content of Hami melon were lower than those of the control group at 28 days after storage,while water-soluble pectin,PG and PE were higher than those of the control group,and the influence of the TRs,the SRs and ARs on the cell wall of Hami melon was more significant,which indicated that vibration accelerated the degradation of pectin during storage and physiological softening of Hami melon,destructed the integrity of cell wall,and ultimately accelerated the aging of melon.4.In order to study the anti vibration strength of vibration in different road transport under adversity,the test used the Hami melon for raw material,the untreated group as experimental control,research on highways,ARs,SRs,and TRs to the influence of storage period and quality of Hami melon,through determination of the electrolyte leakage rate,with the Logistic regression equation,establish Hami melon’ semi-lethal vibration time under the condition of four different roads,also determined the firmness and the total antioxidant capacity.The result shows that the longer the vibration time and the storage time were,the greater the electrolyte leakage rate was.the semi-lethal vibration time for 7 days storage(19.60-14.66 h),the semi-lethal vibration time for 14 days storage(18.99-8.64 h),the semi-lethal vibration time for 21 days storage(6.85-2.66 h),and the semi-lethal vibration time for 28 days storage(2.69-0.01 h)were determined.The Logistic correlation coefficient between 0.95-1 and x~2 test results show that X~2<(?),and P < 0.01.This shows that the relative conductivity of the Hami melon which were processed under vibration stress followed the logistic equation,combined with the firmness and total antioxidant capacity,it can be known that the vibration resistance of Hami melon from strong to weak is: highways,highway secondary roads(SRs),tertiary roads(TRs),and quaternary roads(QRs). |
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