UBC Undergraduate Research

The effect of impact energy and turgor pressure on the bruise volume of BC Royal Gala Apples Shen, Xiao Han; Shan, JinJin


Apple bruising is one of the major causes for economic losses for apple farmers in BC. In this study, the bruise threshold, bruise susceptibility, and bruise volume of the BC Royal Gala Apple were investigated as a function of impact energy. Impact energy was varied using a pendulum testing technique with regular height intervals of 2 cm. Additionally, turgor pressure was adjusted for by immersing the apples in water for 0, 1, and 18 hours, respectively. Impact energy and bruise volume were measured following the Bruise Thickness Method using the LoggerPro and ImageJ analytic softwares. The relationship between bruise volume and impact energy was analyzed using regression models on Excel. These models revealed that in general, apples with higher turgor pressures tend to have lower overall bruise volume when subjected to similar levels of impact energy. Apples with increasing turgor pressure also had the best fit for the model. The bruise threshold of Gala apples was measured to be 0.08 J and bruise susceptibility varied from 6.7 [Formula and equation omitted] in apples without water immersion to 2.31 [Formula and equation omitted] in apples immersed for 18 hours. Immersing apples in tap water for 18 hours was found to be an effective method to reduce apple bruise susceptibility.

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