Compositional changes of sweetpotato as influenced by cultivar, harvest date and cooking

Qualitative evaluation of ten sweet potato cultivars harvested at 90, 105 and 120 days after planting (DAP) was carried out at the research farm of Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India from 2002-03 to determine the optimum harvesting stage, to identify cultivars suitable for table/processing purposes, and to assess the quality of the cooked product. The dry matter content of cultivars over the harvesting stages ranged from 18.11-26.33%, starch 5.55-18.00%, total sugars 1.62-2.94%, ascorbic acid 11.50-28.60 mg/100g and beta-carotene 1200-4360 mu g/100g. Linear increases in dry matter, starch and total sugar content were found between 90 and 120 DAP, while beta-carotene content increased up to 105 DAP. A declining trend of ascorbic acid content was observed with age. It is worthwhile to harvest the roots at around 105 DAP considering all qualitative aspects. Six cultivars ('S -1221', 'Kamala Sundari', 'Tripti', 'WBSP-4', 'BCSP-14' and 'CO-3') were found suitable as table types while none were found appropriate for processing. Consumption of either of the orange-fleshed cultivars ('Kamala Sundari' and 'S-1221') with high retinol equivalents would be advantageous in combating night blindness. The cooked roots of 'Kamala Sundari', 'S-1221', 'BCSP-14', 'BCSP-5' and 'CO-3' were organoleptically rated high in acceptability.