Study On Postharvest Vibration Damage Characteristics Of ’hongmeiren’ Citrus Fruit And Development Of Anti-vibration Packaging

Vibration produced during transportation is one of the important factors leading to fruit damage.‘Hongmeiren’ citrus fruit is a popular variety among consumers in recent years,with high sugar content and good taste.However,due to its low hardness,it is vulnerable to vibration damage during postharvest transportation,which accelerates decay and deterioration.First,the effect of vibration on the physiological quality and metabolism of ‘Hongmeiren’ citrus fruit was studied based on the developed mechanical force decomposition platform.Furthermore,the anti-vibration effect of self-made packaging was evaluated through simulated vibration and road transportation experiment,and the effect of different vibration environmental conditions on the degree of fruit damage were also studied.Then,the acceleration data of the fruit box from Quzhou,Zhejiang to Beijing was collected throughout the whole journey,which provided data support for more realistic simulation of road transportation in the future.In addition,a vibration transmissibility test device was developed to judge the antivibration effect of packaging materials.The main research results are as follows:1.A mechanical force decomposition platform which can study the vibration force in the process of logistics separately was developed.The platform can study the effect of vibration treatment on the occurrence of fruit mechanical damage independently,avoid the interference of collision,friction,rolling and other mechanical forces,and can simultaneously analyze multiple independent fruit samples.The platform can also be used to study the effect of extrusion force and vibration force on the mechanical damage of fruit,and can also be used to study the protective effect of different packaging materials on the vibration damage of fruit.2.Based on the mechanical decomposition platform,the effect of vibration on the physiological quality and metabolism of ‘Hongmeiren’ citrus fruit were studied.After3 h random vibration,the weight loss rate of fruit in the vibration group was 171.43%higher than that in the control group at the first day of storage.The hardness of the vibration group was 20.53% lower than that of the control group on the 14 th day.The respiration rate peaked on the first day after vibration,which was 122.01% higher than that before vibration.After vibration,phenolic acids,flavonoids,terpenoids,alkaloids and other differential metabolites were up-regulated in fruit,and differential metabolites were annotated into secondary metabolite synthesis pathways in both pericarp and pulp.3.An anti-vibration packaging for postharvest logistics of ‘Hongmeiren’ citrus fruit was proposed.The vibration transmissibility of three kinds of packaging(bulk plastic basket,commercial gift box and self-made packaging)were measured.Then the protection effect of different packaging on fruit were compared by simulated vibration experiment and actual road transportation experiment.The results showed that the maximum transmissibility of self-made packaging and the transmissibility of fruit in the low frequency range(3-28.69 Hz)where the fruit was most vulnerable to vibration damage were lower than those of other packaging.Although the bulk plastic basket had the highest cargo density,the damage rate after simulated vibration for 3 h and 10 h and the decay rate during storage were both higher than that of the commercial gift box and the self-made packaging,indicating that bulk transportation was not suitable for‘Hongmeiren’ citrus fruit.In the actual road transportation experiment A(about 13 h),the damage rate of fruit in the self-made packaging was only 16.89% of that of the bulk plastic basket,showing that the self-made packaging has a good protective effect.At the same time,the damage rate of the self-made packaging in the actual road transportation experiment A(8.67%)was similar to the damage rate of simulated vibration for 10 h(6.67%),indicating that the experimental results of simulated vibration are reliable.4.The effect of vibration time and vibration environment temperature and humidity on fruit were studied.The results showed that with the increase of vibration time from 3 h to 10 h,the damage rate of the fruit increased by 2-3 times.When the vibration time was 10 h,the damage rate of the fruit at 20°C(15.56%)was 2.8 times of10°C(5.56%).The damage rate(20.00%)of the fruit after vibration under 70%RH environment was 4.44% higher than that under 90%RH environment(15.56%).5.The acceleration of fruit boxes in the actual road transportation was measured,and the effect of the placement of the fruit boxes in the truck on the damage rate of the fruit was studied.A total of 102,411 acceleration data samples were collected during the whole 29.5h of road transportation,and two power spectral density peaks(3 Hz and16 Hz)were found.The damage rate of the fruit in the rear of the truck was the highest,while the damage rate of the fruit in the front of the truck was the lowest.The weight loss rate of the fruit was significantly higher than that of the front and middle.6.A test device for vibration transmissibility of packaging materials was developed.This device can be used to test the characteristics of vibration transmissibility of packaging materials before real vibration transportation tests,so as to provide experimental data for selecting the packaging materials with the best antivibration performance and reduce the waste of fruit in formal experiments.To reduce the experimental error caused by the gap between the material and the device,the device adopts a multi-layer structure design to make the material to be tested closely fit the device and the vibration table.