Hysteresis characteristics and relationships with the viscoelastic parameters of apples

The hysteresis test was performed to measure the hysteresis properties of Fuji, Golden and Red Delicious apples. Loading speed of the texture analyzer was 2.5 mm/min and loading deformation set 1.0 mm. Hysteresis parameters were compared with the viscoelastic parameters presented by the oscillatory test. Correlation coefficients between viscoelastic parameters and hysteresis parameters was significantly high for Golden Delicious apple, but low for Fuji and Red Delicious apples. For Golden Delicious apple, correlation coefficients were −0.85, −0.81 and −0.80 for hysteresis loss and 0.84, 0.85 and 0.86 for degree of elasticity, with phase lag, loss modulus and dissipated energy, respectively. Multiple linear regression analysis results for three apple varieties that phase angle, loss modulus, complex modulus and dissipated energy had the adjusted R-square values of 0.532-0.687 for calibration model with statistical significances at p < 0.001 and the validation correlation coefficients of 0.704-0.780, when independent variables measured by the oscillatory test were energy loss, hysteresis loss or hysteresis modulus. It should be noted that the hysteresis and the oscillatory tests take quite different approaches to characterize hysteresis phenomenon of apples.