Effect of transport vibration in different levels of road on Hamimelons quality

Abstract: Transport from origin area to main consumption area is needed for improving the economic profit of Hami melon (Cucumis melo var. saccharinus). Transport vibration has an important adverse impact on the ripening of Hami melon. Fruit ripening changes are closely related to cell membrane lipid oxidation and reactive oxygen metabolism process. In order to study the effect of different levels of road transport vibration on active oxygen metabolism and membrane lipid oxidation of Hami melons, the vibration environments of the semi-trailer in highways, arterial roads, secondary roads and tertiary roads were simulated and relative indices were measured. In this study, Huajun semi-trailer was used to measure transport vibration, and the data were collected once every 3 minutes for 2 seconds as the semi-trailer was at the speed of 61-90 km/h. Then the data were used to drive a shaker to simulate the transport vibration. The melons were packaged with net packages and placed in corrugated fiberboard containers, and were treated under transport vibration of different grades of roads with the untreated as control samples. During the vibration treatment, the environmental temperature was 23 oC. After treatments, all of the melons were stored at 23 oC. The indices included respiration rate, firmness, relative electric conductivity, lipoxygenase (LOX), malondialdehyde (MDA) and reactive oxygen species (ROS). The results showed that after the storage of 28 days, the respiration rate of Hami melons under the vibration treatment in highways, arterial roads, secondary roads and tertiary roads was 1.31, 1.61, 2.03 and 2.21 times that of the control group, respectively, and the difference was significant (P<0.05). The firmness of Hami melons under the vibration treatment in highways, arterial roads, secondary roads and tertiary roads was 15.27%, 35.27%, 60.50% and 77.47%, lower than that of the untreated, respectively, and the difference was significant (P<0.05). The electric conductivity of Hami melon with different road vibration was significantly higher than that of the control. And about the decay area, the Hami melons of the control group were more intact, while the vibration group had different degrees of decay, of which the melon decay areas were 0-5% for transport vibration treatment groups of highways and arterial roads, and 16%-25% for transport vibration treatment groups of secondary roads and tertiary roads. It was clear that the vibration accelerated the fruit softening, accelerated the cell membrane lipid oxidation, promoted the activity of LOX, and accelerated the process of free radical reaction, so that the ROS content continued to increase, which resulted in more MDA, and caused the cell membrane to be damaged and the relative conductivity to increase. The influence of the transport vibration of tertiary roads and secondary roads on Hami melons was more significant than that of highways and arterial roads. And ROS content of Hami melons treated by transport vibration of tertiary roads was higher than that of the roads of other grades (P<0.05), and the effect of tertiary roads and secondary roads on the cell membrane of Hami melon was more significant (P<0.05), which showed that with the increase of vibration power spectral density, the quality of Hami melon was affected by the transport vibration. The results provide a reference for finding ways to reduce the influence of transport vibration on the quality of melon.