STRESS-RELAXATION IN CHERRY FRUIT

Stress relaxation in three varieties of cherries was studied using the penetration test with a cylindrical pin, 4 mm in diameter, having a f lat tip, One half of the fruit was modified by partial skinning, since experiments show that skin approximately doubles the apparent modulus of elasticity of the cherries, The skin also obscures a part of the f ruit's distinctiveness, and affects the experimental results, even if a part of the fruit has been removed, A thermal activation theory with the residual part of stress was used to evaluate the stress relaxatio n experiments, and yielded results very similar to those previously ob tained for vegetable flesh, Real consistency was observed mainly for r esidual stress and activation volume. It was observed that the relatio n between parameters Ct and log bt, and the initial relative slope of the relaxation curve provides information on fruit firmness. Copyright (C) 1997 Elsevier Science Ltd.