Ripening Patterns within a Peach as Indicated by Force and Soluble Solids Concentration

Abstract

Variability in maturity within a peach (Prunus persica, L. Batsch) fruit was estimated by measurements of force and the soluble solids concentration (SSC) at 16 coordinates around the peach at five maturity stages: 1) about one-half final swell (immature); 2) 85% final swell (green); 3) firm-ripe and similar to chip #3 of the Clemson Univ. system; 4) firm-ripe and similar to chip #5; and 5) tree-ripe. Firm-ripe 3 and 4 stages were firm enough to ship, but the tree-ripe stage was too soft. Firmness measured with a 4.7-mm-diameter penetrometer tip from two cultivars indicates a strong trend for the peach tip and cheeks to be firmer than tissue at other coordinates. Coordinates at the equator and around the stem end are generally firmer than coordinates at lat. 45°N, particularly in stages 3, 4, and 5. The SSC in juice from a cylinder of fruit adjacent to the puncture was higher at long. 90°E-W than at the sutures and higher at lat. 0° than at 70°S. Variance increased for force and decreased for SSC between maturity stages to the firm-ripe stage. The coordinate technique might be used to characterize and select cultivars that would be most suitable for once-over harvests.