SIMULATED PACKING LINE IMPACTS FOR APPLE BRUISE PREDICTION

ABSTRACT Impact pulses recorded by an Instrumented Sphere (IS) as it moved with apples through 12 commercial apple packing lines were analyzed to determine peak g and velocity change. Peak g ranged from 20 to 130 g (1 g = 9.81 m/s2) and velocity change (area under the impact curve) from 0.1 to 3.0 m/s. These impacts were simulated in the laboratory using different surfaces that were calibrated using the IS. Taula Red' and *Golden Delicious' apples were dropped onto these surfaces and the resulting bruises were measured. The lowest impact threshold for bruise development (brown tissue under the skin) was 40 g for Taula Red' apples and 30 g for *Golden Delicious' apples. This occurred 1 day after harvest for Taula Red' and 3 days after harvest for *Golden Delicious' apples. Multiple linear regression models were formulated for average bruise diameter for each variety of apple. The equations explained 85% of the variation in bruise diameter for Taula Red' and 57% for *Golden Delicious' apples.