Mechanical behavior and damage of Pink Lady apples

Research was conducted to investigate the type of damage and mechanical behavior of Pink Lady apples during post-harvest operations. Samples of apples of this new cultivar were subjected to drop tests to simulate the kind of impact recorded in Italian sorting and packing lines by means of an instrumented sphere. A simple device with an acceleration transducer mounted on the apple and an acquisition system were used to cause an impact and to describe the mechanical behavior of the fruit. Data were treated statistically employing logistic regression and multiple linear regression analyses to determine correlations between probability, characteristics of damage and parameters describing impact and characteristics of the apples. A logit model was used to assess the probability of damage occurring to fruit. In this model (R2 L = 0.380) the characteristics of the impact and the firmness of the flesh of the fruit were found to be significant. The kind of damage appeared to be significantly influenced by the impact level and, in general, by the mass, the sugar content and the curvature radius at the point of impact on the apples. Coefficients of determination of the models to predict characteristics of damage were from 0.104 to 0.312. The curvature radius was correlated with peak acceleration of the apples, too (R2 = 0.210). Although the prediction power of the statistical models was low, they were useful to check significance and analyze correlations between parameters.