POTATO IMPACT DAMAGE THRESHOLDS

Abstract

Bruise damage to potato tubers (Solanum tuberosum) appears as a result of impacts and compression.Substantial bruising in potatoes occurs during harvesting and handling operations, costing the average grower between$10,000 and $50,000 annually, depending upon the years growing and harvesting conditions, cultivar, cultural practices,and tuber condition. This study focused on the effects of temperature and cushioning on bruising (impact damage)thresholds of Russet Burbank potatoes. The results provide potato tuber bruise probability reference data for use with theinstrumented sphere impact evaluation device.<br><br>Russet Burbank potatoes tubers at 10, 15.5 and 21C were dropped from 10 heights onto a steel surface, and onto6.3mm (1/4 in.), and 13-mm (1/2 in.) thick Poron surfaces (10 tubers/treatment). Tubers at the lowest temperaturewere the most susceptible to damage. Cushioning the impact surface reduced the amount of bruise in all cases. As dropheight increased, bruise type shifted from blackspot to shatter bruise and cracking, implying a continuum of damage typethat is dependent at least in part upon approach velocity. The drop heights which bruised 10% of the tubers at 10 and15.5C were then translated into corresponding peak acceleration (g) and velocity change (v) values necessary for usein interpreting instrumented sphere data. Resulting stem-end zero-damage allowable drop heights for 250 50 gramRusset Burbank tubers onto a steel anvil were 25, 30, and 50 mm (peak accelerations of 69, 81, and 122 G), respectivelyfor tuber temperatures of 10, 15.5, and 21C. Adding 6.3-mm thick Poron 15250 to the anvil increased allowableheights to 200, 225, and 250 mm (97, 110, and 122 peak G), respectively for 10, 15.5, and 21C; and adding 13-mmPoron 15500 to the anvil increased allowable drop heights at least another 100 mm.