f. pileh

Evaluation of changes in physical and mechanical characteristics of fruits has special importance for better management of harvesting and storage process of horticultural products. In this study that was conducted in a factorial experiment based on completely randomized design with four replications, the effects of harvesting time and storage duration was studied on changes of physical and mechanical characteristics of 'Bidaneh Sefid' grape fruits. The fruits were harvested at three different stages from 4 September to 29 September at 12 days interval. Fruits stored two months at temperatures of 1±0.5 °C and 90-95% relative humidity. During ripening and cold storage, some of the physical and mechanical characteristics such as TSS, berry density, berry dimensions, cuticle thickness, skin weight, fresh weight, berry dry weight, weight loss, fruits color, firmness, and tensile strength of the skin and tail were evaluated at 20 days interval. The results showed that over harvest time, the density of berry and weight of fruit skin increased and berry cuticle content decreased. Berry fresh weight increased with delay in harvesting and decreased during storage. With increase in ripening degree, a significant increase was observed in the weight loss of fruits during storage. Delay in harvesting, and also during storage period, decrease in firmness of berries and Skin tensile strength was observed. Tail separation force increased for second harvest samples but it decreased for the third harvest one. However, tail tensile strength was maintained at the higher level for harvested samples in the third harvesting time until 40 days storage period.