Dangler for Accelerated Dehydration: A Novel System for Assessing the Impacts of Relative Humidity on Fruit Water Loss During Cold Storage of Blueberries

Abstract

Blueberries are prone to dehydration during storage. Firmness is one of the most critical quality attributes associated with this period, with the loss of water from the fruit representing the most significant limitation for the fresh market. Therefore, one of the great challenges is maintaining the quality characteristics of the fruit in shipments by sea, which can take up to 60 days when sent from the southern hemisphere to the northern hemisphere. The random arrangement of each fruit within a packaging unit (different proportions of the stem scar and cuticular surface exposed to the environment) represents an essential source of variation in the prediction of softening during the storage period. A special device, referred to as a dangler for accelerated dehydration (DAD), was designed to expose nearly the entire fruit surface to the environment and determine the impact of factors such as relative humidity and the role of the stem scar and cuticle on fruit water loss. Consequently, to evaluate the ability of DADs to find differences in fruit dehydration, blueberries sampled at early, peak, and late harvest dates were placed in DADs and exposed to three controlled levels of relative humidity (30%, 65%, and 96% relative humidity; 1.2 ± 0.7 °C) for 10 days. Berries within the DADs were untreated, immersed in hexane for 5 seconds to remove bloom, painted with quick-drying nail polish on the pedicel end to seal the stem scar or immersed in hexane for 5 seconds, and painted with quick-drying nail polish on the pedicel end. At each harvest, fruit weight loss was significantly affected by the fruit and RH treatments, as well as the interaction between them. A regression analysis of the control treatment indicated that water loss at lower relative humidities occurred faster in fruit from the first harvest. The results reveal that DADs can be used to characterize preharvest and postharvest stimuli at an individual level and within a short time (10 days).

Keywords

• fruit firmness
• postharvest fruit quality
• relative humidity gradient
• vaccinium corymbosum
• vapor pressure deficit gradient