RIPENING OF KIWIFRUIT FOLLOWING SIMULATED BRUSHING WITH COMMERCIAL BRUSHES

Brushing of 'Hayward' kiwifruit [Actinidia deliciosa (A. Chev.) C.F. L iang et A, R. Ferguson var, deliciosa] to remove trichomes reduced the ir marketable life. Fruit were brushed with polypropylene brushes havi ng bristles of 0.60, 0.50, 0.30, and 0.25 mm in diameter. The two smal lest-diameter bristles removed about 0.1 g of trichomes per fruit. The larger diameter bristles removed 12% more material, including some su rface tissue particles, Brushing accelerated ripening during subsequen t storage of fruit for 4 days at 4C as indicated by increases in ethyl ene production and soluble solid concentration and a decrease in firmn ess. The larger the bristle diameter, the greater the acceleration of ripening. The largest diameter did not accelerate ripening as much as 0.50-mm bristles due to the lower resistance to bending (0.85 N and 2 N for 0.60- and 0.50-mm bristles, respectively) and their greater leng th. Small surface wounds, visible under the microscope, may have cause d the higher ethylene evolution and the consequent ripening response.