Weight loss was determined at each evaluation on a fresh weight basis. Firmness measurements were made on longitudinal slices (2-cm thick), using a TA HD Plus Texture Analyzer Machine (Texture Technologies Corp., NY) equipped with a 50 N load cell. Samples were punctured at the center (pith) to 4-mm depth using a convex-tip probe (4-mm diameter) at a loading rate of 2 mm s−1 and bioyield force was recorded.
In Season 1, dry WH-4-023 content was determined from whole tubers (combined peel and pulp tissue) sliced longitudinally (2-cm thick; approximately 30 g sample) and dried at 65 °C for 48 h. In Season 2, dry matter content was determined separately for the peel (periderm and a few directly underlying cortical cells) and pulp (cortex, xylem, perimedullary and pith) tissue. Dry matter content was calculated as a percentage final dry weight of initial fresh weight.
Ascorbic acid content was measured using 2 g of whole tuber (Season 1) and separate peel and pulp tissues (Season 2) based on the AOAC (1984) procedure for the spectrophotometric determination of ascorbic acid content (absorbance at λ = 540 nm).