Percentage of decay in packaged blueberries stored at various temperature. Harvested blueberries should be cooled as soon as possible but always within 4 hours of harvest, if possible. This may require more than one pickup or trip to the cooling facility during a day of harvesting. However, the increase in shelf life and overall quality will make it worthwhile. No fruit, particularly well-ripened fruit, should ever be held all day without cooling.
Blueberries remain alive after harvest, respiring and producing heat.
At a temperature of 80 F, blueberries can produce as much as 22,000 Btu per ton per day from the heat of respiration. Unless this heat is removed by cooling, it can cause a rise in temperature of as much as 6 F. Cooling lowers the respiration rate, slowing the ripening process and the accompanying inevitable decline in quality. In other words, blueberries held at 40 F have nearly 20 times the shelf life of those held at 80 F. Softening is the most visible physiological damage resulting from overripening. Most North Carolina blueberries in wholesale channels receive some cooling. However, a portion may continue to reach the consumer in poor condition as a result of insufficient cooling.