Abstract
Handling potatoes at harvest and throughout transloading operations can result in two main impact injuries: blackspot and shatter bruises. The objective of this study was to examine the development of blackspot and shatter bruises over a 24 to 48-h period as influenced by cultivar, impact height and holding temperature with the intent to identify whether more rapid, on-farm bruise evaluations could be used to facilitate change in harvest management. Tubers (8.9 C pulp temperature) were bruised using a free-falling 100 g weight set at a height of 18 or 30 cm (Russet Burbank and Ranger Russet) and 30 cm for Russet Norkotah to deliver two uniform impacts on each tuber end. Impacted tubers were held at either 21.1 C or 8.9 C and evaluated after 1, 2, 3, 4, 5, 24 and/or 48 h. Peeled tubers were evaluated for incidence, color intensity, and depth of blackspot bruise and shatter bruise incidence. The change in flesh color at the impact site from pink to brown primarily occurred within one to three hours after impact, and as a result the incidence of pink discoloration declined rapidly after that time. Over 70% of the total blackspot bruise incidence was observed after four hours, depending on the impact force and cultivar. Likewise, 70% of the total bruise depth observed tended to develop within five hours after impact. The bud end had lower overall blackspot bruise incidence, color intensity and depth and was slower to develop discoloration compared to the stem end. Time after impact was not a major component to shatter bruise development. Rapid bruise assessment can be conducted between two to five hours for Russet Burbank, two to three hours for Russet Norkotah, and by one to two hours for Ranger Russet. This study confirmed monitoring for new and developing bruises can be utilized as an early indicator of damage incidence in samples from handling operations.