INFLUENCE OF IMPACT SURFACE AND TEMPERATURE ON THE RIPENING RESPONSE OF KIWIFRUIT

Kiwifruit (Actinidia deliciosa) at a typical harvesting stage were sub jected to a drop height of 30 cm onto a steel plate (impact injury), a nd 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 involv ed comparisons of smooth steel plate with fine (280 mesh) and coarse ( 100 mesh) sandpaper surfaces, again measuring SSC, deformation and eth ylene production. Fine sandpaper generally produced greater increases compared with steel than did coarse paper. Chilling to 4 degrees C eit her on impact or during storage reduced increases in SSC and deformati on responses. It is concluded that careless handling and rough surface s in packing materials should be avoided, but prompt cooling will dela y the onset of deterioration resulting from mechanical damage.