| Zaosu pear is prone to the loss of green color in its pericarp and the softening of the fruit flesh after a normal temperature transportation, while the low temperature storage after the transportation may result in the shriveling of the fruit pericarp and the turning tough of the fruit flesh caused by a severe water loss when the humidity is too low. In addition, the Zaosu pear is sensitive to CO2, and about 3%- 4% of the CO2 concentration will cause the browning of the pulp core and therefore will not be suitable for spontaneous modified atmosphere packaging. The present tests of Zaosu pear storage focus mainly on normal temperature 1-mcp and the fruit wax coating technology, with the transportation features and the suitable environments for low temperature storage of Zaosu pear rarely reported. So the research on the transportation features and suitable storage environments for Zaosu pear, and the adoption of appropriate measures to alleviate all sorts of problems in the process of transportation and storage, have an important theoretical and guiding significance on the improvement of fruit postharvest storage and transportation technology levels of the Zaosu pear, as well as the better maintenance of the commodity features of Zaosu pear to improve economic benefits.This paper studies the impacts of different temperatures, cooling ways, microporous membrane exposure and covered openings on the low temperature storage and shelf life breath,ethylene, chromatic aberration, titratable acid, soluble solid, hardness, weight loss, and good fruit rates for postharvested Zaosu pear. A research was conducted on the differences in the vibration acceleration,temperatures and humidities between the different parts of vehicles during the transportation, and also on the differences in the physiological indexes between the pear fruits before the transportation and that after the transportation. The conclusions are as follows:1. Transportation:(1) The vibration occured mainly in the z axis, with the vibration intensity gradually enhanced from the top to the bottom, from the front to the back. There were significant differences among the vibration accelerations of all the nine parts. Damage indexes were obtained by the measurement of a simulated transportation, with the results showing the lightest damage in central part and the most serious damage in the upper part. The interactions among height, position, and height x position had significant impacts on the results of the vibrations. ⑵ There were significant differences among the temperatures and humidities of the nine parts, and the interaction among the height, position and height x position had significant influences on the temperatures and humidities, and this was also verified by the weight loss ratio, with the lowest temperature, the highest humidity and the lowest weight loss ratio in the middle and lower parts. The front three treatments had more fierce changes in temperatures, humidities and physiology than that of other treatments.(3) The front three treatments had high temperatures and low humidities, with the soluble solids content significantly decreased, and with a relatively low titratable acid content. The value of a* for chromatic aberration greatly reduced, with the value of b* decreased and the value of L* slightly lowered. At the back, the value of a* reduced most while the front reduced little, resulting in the differences from the temperature results in the process of transport, and it could be speculated that the stronger vibration at the back caused the fruit pericarp to turn yellow rapidly.2.Slow cooling combined with low temperature storage:(1) The temperature generated a significant impact on the changes of physiological metabolism of Zaosu pear; a low temperature significantly inhibited the respiration intensity of the pear fruit, with a lower ethylene release, and significantly inhibited the trend of turning yellow of pericarp of Zaosu pear, with a high good fruit rates.(2) The impact of humidity on the physiological indexes of Zaosu pear was only shown in respiratory intensities and weight loss rates: the No. 2 and No. 3 treatment of the three treatment groups failed to show a significant difference in respiration intensities, probably resulting from the promoting effect of humidity on breathing. The weight loss ratio for microporous membrane covered openings was low, and the weight loss ratio for exposure processing at the end of storage was close to 5%, with the pericarp shriveled, resulting in the loss of the commodity value.(3) No pulp core browning was found in Zaosu pear after 240 d of storage, and the tested CO2 content in the microporous membrane did not exceed 0.4%, thus verifying that the microporous membrane did have a good transmittance rate for gases.(4) The minimum temperature during storage was 1.5 degrees Celsius, but given the fact that no chilling injury occurred, slow cooling storage failed to apply to the storage of Zaosu pear: the ethylene peak of the two slow cooling treatment groups advanced by 30 d when compared with the quick cooling groups. The longer the time of cooling process was, the closer it was to 0 for the value of a* for the chromatic aberration at the end of storage. ⑸ The hardness generally showed a declining trend, with a quick decline at 150 d and then a slight recovery from that, while the titratable acid was found to fall sharply at 150 d. The heat treatment of soluble solids first went up rapidly and then declined slowly, with a lower value during the entire course of the low temperature treatment. These results suggest that the appropriate storage conditions for Zaosu pear are as follows: openings covered by the microporous membrane,-0.7 ℃, rapid cooling way; and the storage time is not appropriate to exceed 150 d.3. Shelf life:(1) The weight loss ratio of high humidity treatment at 20 d was about 2%, similar to that of the whole low temperature storage period, indicating that temperature had an impact on the weight loss ratio; the good fruit rate was high for low temperature storage; ⑵ The differences between the respiration intensities mainly lied in the cooling modes, and the climacteric of a rapid fall occurred earlier than that of the two slow descent treatments, but the two slow descent groups generated less ethylene, and this was consistent with the results of cryopreservation, showing that the slow cooling might lower the production of endogenous ethylene of Zaosu pear.(3) Chromatic aberration: it showed advantages when processed with low temperature treatments at 10 d, while the values of a* for each treatment chromatic aberration had no significant differences at 20 d during the shelf life, thus the above results showing that the shelf life of Zaosu pear was about 10 d. |
PDF Full Text Request