EFFECT OF IMPACT BODY SHAPE ON SUBCUTANEOUS TISSUE DISCOLORATION IN POTATO-TUBERS

In the modern potato industry the economies of scale demand that all p roduction and handling processes must be highly mechanized. Mechanizat ion is usually associated with increased damage. The shape of impactin g surfaces is an important factor that affects damage in potatoes. We investigated the relation between the radius of curvature of the impac t body at a given level of energy and the resulting volume and depth o f discoloured tissue as measure of damage. Tubers were impacted at a d esired rate and by a desired impact body shape with a computer-control led pendulum. The tubers were from plants grown at mio different level s of potassium fertilizer (i.e. susceptibilities to tissue discolourat ion) and stored for 3, 5 or 7 months. A spherical impact body doubled the volume and depth of discoloured tissue, relative to a non-spherica l impact body. The differences in volume and depth of discoloured tiss ue after impact with spherical impact bodies (radii of curvature 30 or 15 mm) was minimal. Reducing the impact energy from 0.600 to 0.067 J yielded an average reduction of the volume of discoloured tissue of ca 95% and an average reduction of the depth of discoloured tissue of cn 80%. Future potato handling lines may take these findings into accoun t, by lowering the use of spherical impact bodies and the level of imp act energy.