MODELING BLUEBERRY FIRMNESS AND MASS LOSS DURING COOLING DELAYS AND STORAGE

Blueberry mass and firmness losses were measured to determine the effect of cooling delays at selected temperatures in postharvest environments. Models were developed from the slopes of firmness and mass values plotted against time for four temperatures (4°C, 21°C, 27°C, and 32°C) and 95% relative humidity. The models were validated by holding other sets of blueberries at three temperatures (21°C, 27°C, and 32°C) and at 95% relative humidity for cooling delays of 0, 2, 4, 8, 12 and 24 h before storage at 4°C and 95% RH up to 96 h. The models developed were suitable for evaluating the benefit of lowering temperature during cooling delays of selected durations or the benefit of reducing cooling delays at specified temperatures. The impact of cooling delays was less than expected when compared with losses caused by low-temperature storage for only four days. Additional studies are needed to model the effect of various relative humidity levels and to learn the extent of variation in the rate constants for different cultivars and different crops.