ABSTRACT

Yellow root cassava also known as pro- vitamin A cassava, a result of biotechnology research, can be used to produce cassava moimoi, chiii-chin, gari, fufu and High Quality Cassava Flour (l-IQCF). The carotenoids arc group of mainly lipid-soluble compounds responsible for many of the yellow and red colours of plant and animal products. The mechanisms of carotenoid degradation in Pro vitamin A cassava during processing is of concern. The effect of drying methods on the retention of total carotenoids (TC) in pro-. vitamin A HQCF was studied, two varieties of yellow-fleshed (UMUCASS 36 and UMUCASS 37) cassava roots were used for the study. The two varieties were prepared as raw and blanched samples by washing, peeling, grating, dewatering, pulverizing, and processed into FIQCF using different drying methods (Tray, oven, indirect active solar) while direct sun drying method was used as check. Results showed that while the fresh cassava roots of the two varieties had moisture content of 71% and 82% fresh weight (FW), their TC content were 8.23 Rg'g and 8.15j.tg/respectively, the blanched cassava roots (UMUCASS 36B and UMUCASS 3B) had moisture content of 71.68% and 82.56% and TC content of 6.66 j.tg/g and 5.80 p.glg respectively. There was significant difference (P < 0.01) in the initial TC content of the two cassava varieties and their blanched samples. Results indicated that the extent of carotenoids retention varied with the methods of drying, the highest retention was observed in tray drying (80% TC content retention) followed by indirect active solar drying (54% TC content retention) and oven drying (46%). The lowest retention was recorded in the sun (check) drying method (20% TC content retention). The Higher Temperature-Short Time (HTST) combination rather than low temperature-longer time resulted in higher retention of TC. The highest TC retention was observed in oven dried sample at 120°C for 1 hour (55.1%) and the lowest TC retention was observed at 60°C for 3 hours (39.75%). Tray dried HQCF sample at 80-95°C xii for 1 hour showed a retention of 9 1.65% and 68.75% at 55-70°C for 2 hours. During storage, TC in UMUCASS 37A (not blanched) decreased from 93.3% to 43.8% within 2 weeks of storage, while TC in UMUCASS 3Th (blanched) decreased from 91.4% to 44.1% under same storage condition, suggesting that blanching may improve carotenoid stability over time.