PHYSICAL AND MECHANICAL-PROPERTIES OF FRESH AND STORED SWEET ONIONS

Some physical and mechanical properties of a sample of 'Granex-Grano' type sweet onions were examined in an attempt to more deeply understan d the conditions under which those onions may most appropriately be gr own, harvested, stored, processed, shipped, and marketed. Those onions evaluated had a mean mass, surface area, volume, and density of 98 g, 111 cm(2), 95 cm(3), and 1100 kg/m(3), respectively. The overall mean equatorial diameter was 62 mm and the mean polar diameter was 42 mm. Of the mature onions examined, 59% of the onions were oblate and 41% w ere prolate. Crushing load and puncture force are indications of mecha nical strength of the onions to withstand mechanical harvesting and po stharvest handling. Onions evaluated from this study had a mean crushi ng load of 26.4 N and puncture resistance of 25.0 N.