Impact bruise responses for "Jazz™ apple on different materials of catch surface

To gain an understanding on how cushioning materials could absorb the impact force to reduce fruit bruising in shake-and-catch harvest system, an experimental study using a developed pendulum impact platform was conducted to investigate the bruise response to impact forces. Three types of cushioning materials (Polyurethane foam) were used as impacting surface by covering on an aluminum plate. Polyurethane foams with same thickness(12.7 mm) but varying pressure rating (at 25% deflection) were used to exert impact on a stationary whole apple sitting freely on a horizontal surface. Seven different levels of impacts which were applied at three different zones of 'Jazz' apples: top, middle and bottom. Each level was repeated 50 times at each zone. Results showed that no apple bruising was checked when impacted on or below 22 N by the aluminum plate, regardless of impact zones. The non-bruising impact force increased to 95, 160 and 160 N after foams with 2.1(Foam 1), 4.8 (Foam 2), and 9.7-11 kPa (Foam 3) pressure ratings were used respectively. Based on USDA Grades and Standards, it was found that a 100% of apple would maintain "Extra Fancy™ quality under 115, 171, or 180 N of impact force when impacted respectively by the tested foams. These results indicated that Foam 2 and Foam 3 provided better cushioning as the fruit were maintained at fresh market quality level compared to the same with aluminum plate and Foam 1, while the difference between Foam 2 and Foam 3 was slight.