Effect of Fruit Size and Maturity on Selected Mechanical Properties of Tomato

The losses in fruits and vegetables in various postharvest operations remained high in which tomato is one of the major vegetable fruit. Tomato is a sensitive vegetable whose quality is substantially reduces due to physical damage encountered by various mechanical forces in harvesting, handling and other postharvest operation. In this study an attempt was made to determine mechanical properties such as fruit picking force, coefficient of friction, impact energy force and fruit failure stress which play a major role in design and development of production operations, handling and processing machinery and equipment. The results showed that the fruit picking force increased with increase in size of fruit, recoding highest force 13.60 N with fruit size 55.82 ± 5.09 mm. The fruit size and ripening stage individually influenced the static coefficient of friction significantly. The impact energy force decreased from 37.30 to 35.11 N as the fruit size decreases large to small. The tomato fruit failure stress decreased 56.35%, indicating green tomatoes were more firm than the full red tomatoes. This is an indication for internal structural changes in cell walls of fruits due to various chemical changes as maturity stages increases causing the fruits more susceptible to physical damage due to mechanical force factors which occurs in harvesting and handling processes.