Environmental variables in packing houses and their effects on the quality of grapes

ABSTRACT The aim of this study was to characterize the thermal environment in the selection and packing areas of a packing house and its effects on the quality of table grapes produced in the São Francisco Valley, Brazil. The thermal environment was monitored during the winter and summer seasons. The highest value of air temperature (Tair) and the lowest relative humidity (RH) observed in the packing house were 35 °C and 40.0%, respectively, obtained during the summer, for 8 h. After observing the thermal environment data of the packing house, simulations were performed to evaluate the effect of the ideal environmental storage conditions and observed thermal conditions on the postharvest quality of “Thompson” grapes. Grapes were harvested and stored directly at the ideal temperature and RH of 0 °C and 90%, respectively, or previously exposed to a temperature of 35 °C and RH of 40% for 8 h, the thermal environment observed in the evaluated packing house, followed by storage at 0 °C and 90% RH. Fruit exposure to high temperature and low RH before the ideal storage conditions resulted in higher loss of berry firmness and weight, along with increased soluble solids and dry matter content of rachis and berry. Based on these results, the environmental conditions observed in the packing house result in berry dehydration, which accelerates the loss of fruit quality during storage.摘要 本研究旨在表征巴西圣弗朗西斯科谷某包装厂分选与包装区域的热环境，及其对该产区鲜食葡萄品质的影响。研究于冬季与夏季两季对该区域的热环境开展监测。该包装厂监测到的最高气温（Air Temperature, Tair）与最低相对湿度（Relative Humidity, RH）分别为35℃与40.0%，于夏季出现，持续时长8小时。在获取该包装厂的热环境监测数据后，本研究开展模拟实验，以评估理想贮藏环境条件与实测热环境条件对“汤普森”（Thompson）葡萄采后品质的影响。实验将采收后的葡萄分为两组：一组直接置于0℃、相对湿度90%的理想温湿度条件下贮藏；另一组则先暴露于本次评估的包装厂实测的35℃、相对湿度40%的环境中8小时，随后再以0℃、90% RH的条件贮藏。相较于经理想贮藏条件直接处理的葡萄，经高温低湿环境预处理的葡萄，其浆果硬度与重量损失更高，同时果穗与浆果的可溶性固形物及干物质含量均有所升高。基于上述实验结果，该包装厂实测的环境条件会引发浆果脱水，进而加速贮藏期间果实品质的劣变。