On-farm blast freezing of Saskatoon berries

Abstract

Experiments were performed with individual saskatoon berries under controlled conditions to determine freezing characteristics. The air velocity, the temperature of the freezing air, and their interaction were statistically significant (P > 0.0001) on the time for saskatoon berry to drop in temperature from 0 to -10C. A 2.2 kW (3 hp) prototype freezer was designed and constructed on a saskatoon farm, and tested in the 1999 and 2000 harvest years. At the beginning of a harvest day, the temperature of the prototype freezer was below -20C, the initial temperature of berries entering the chamber was approximately 5C, and the berries reached a temperature of -10C within 1 h. At the end of a harvest day, the chamber temperature had risen to -12C, the initial temperature of the berries was between 15 and 20C, and the time for the berries to reach -10C was greater than 4 h. (Abstract shortened by UMI.)