Abstract
The peel color index and soluble solid concentration of ‘Koshisayaka’ pears after harvest increased during ripening at 20°C, while the flesh firmness, elasticity coefficient, viscosity coefficient and elasticity index of the fruit decreased. When the fruit reached the edible-ripeness stage 12 days after harvest, the values of those characteristics were 9.3 (peel color index), 12.7 Brix % (soluble solid concentration), 1.4 N (flesh firmness), 1.8 × 106 (elasticity coefficient) and 1.1 × 107 (viscosity coefficient). In addition, the elasticity indices that were calculated from the frequency of second resonance and the third resonance were 9.5 × 106 and 17.4 × 106, respectively. Film packaging of the pear fruit resulted in inhibition of moisture loss, yellowing of the peel, softening of the flesh and saccharification of starch during ripening. The characteristics of the film-packaged fruit 12 days after harvest were 3.7 (peel color index), 20% (potassium iodide reaction), 12.5 N (flesh firmness), 15.0 × 106 (elasticity coefficient), 15.0 × 107 (viscosity coefficient), 29.5 × 106 (Emf2) and 66.2 × 106 (Emf3). These findings clarify the ripening characteristics of ‘Koshisayaka’ pear fruit and the delaying effect of film packaging on fruit ripening. The delaying effect on fruit ripening is suggested to be due to decreased level of oxygen in film. Furthermore, the possibility of a nondestructive method for estimating the ripening stage is suggested by the correlation between the elasticity index and fruit softening.
