Influence of impact surface and temperature on the ripening response of kiwifruit

Kiwifruit (Actinidia deliciosa) at a typical harvesting stage were subjected to a drop height of 30 cm onto a steel plate (impact injury), and to abrasion injury by being drawn under pressure across a piece of packing-case wood. Reactions in terms of soluble solids content (SSC) and deformation measurements of flesh and core tissue, were assessed. Impact caused greater increases in SSC and deformation than abrasion, but both were greater than controls. More detailed impact tests involved comparisons of smooth steel plate with fine (280 mesh) and coarse (100 mesh) sandpaper surfaces, again measuring SSC, deformation and ethylene production. Fine sandpaper generally produced greater increases compared with steel than did coarse paper. Chilling to 4 degrees C either on impact or during storage reduced increases in SSC and deformation responses. It is concluded that careless handling and rough surfaces in packing materials should be avoided, but prompt cooling will delay the onset of deterioration resulting from mechanical damage.