Apple Impact Damage Thresholds

Drop tests were conducted using an Instrumented Sphere (IS) and four varieties of apples to determine the impact conditions which initiate bruising. ‘McIntosh’ apples were found to be the most sensitive of the apple varieties. Bruising was initiated at an estimated 2.0 mm (0.08 in.) drop onto steel for large ‘McIntosh’ apples, the day after harvest. The IS recorded a 20 peak G impact for this drop condition. Bruise threshold response lines for ‘McIntosh’ were developed and combined with IS impact response lines for typical surfaces used on apple packing lines. This information was incorporated into the IS software, allowing the analysis of impact data based on the probability of occurrence of apple bruises. These estimates can be used to develop conservative design estimates for apple packing line changes, as well as the practical application and choice of cushioning for hard surfaces.