PERFORMANCE OF AN INSTRUMENT DESIGNED FOR,AND EVALUATION OF METHODS TO ASSESS,PEACH FRUIT IMPACT BRUISE SUSCEPTIBILITY1

A simple, inexpensive device was fabricated for imposing drop impact loads on fruit and tested using a 0.5 J load on peach (Prunus persica (L.) Batsch] fruit harvested at two maturity stages. The device consists of an electromagnet to secure a metallic mass above the fruit, a height adjustment for positioning the mass, a foot pedal switch for interrupting current to the electromagnet, allowing the mass to strike the fruit, and a thick aluminum base to prevent fruit movement upon impact. Following impact, fruit were stored at 2C for one week (to simulate impact damage during harvest and packing, prior to short term cold storage). Impact bruise susceptibility was assessed after storage by bruise occurrence (without regard to bruise size), and by bruise severity (measured as bruise depth, bruise width and bruise discoloration). Maturity at harvest had no effect on bruise occurrence, but did significantly effect bruise severity. Bruise depth was more sensitive than bruise width or discoloration to differences between cultivars. Cultivar ranking for bruise susceptibility differed, depending on the parameter used to obtain the ranking.