ABSTRACT

 This study evaluated the nutritional and phytochemical properties, its retention/loss in       five cultivars of sweet potato flour (Umuspo3, Umuspo1, Tis87/0087, Ex-igbariam and       Tis8165) as affected by unit operations (peeling, oven drying and milling). The result            showed that physicochemical properties of the five cultivars were significantly (P<0.05)     affected by cultivar variation and unit operations. Umuspo1 and Umuspo3 flours had the       highest protein (7.63% and 6.83%), minerals (33.0% and 30.13% for phosphorus, 1.72mg/100g and 1.69mg/100g for calcium,0.39mg/100g and 0.35mg/100g, for          magnesium,136.91mg/100 and 137mg/100g for sodium, 0.12 mg/100g and 0.21mg/100g       for iron, 214.19mg/100g and 178.46mg/100g for potassium), flavonoids (52.27mg/100g,           and 50.09mg/100g), total carotenoid (7.03mg/100g and 7.01mg/100g), beta-carotene             (5.02mg/100g and 5.00mg/100g), vitamins B₂ (0.49mg/100g and 0.57mg/100g)_, B₃             (0.92mg/100g and 0.97mg/100g) and C (49.06mg/100g and 47.69mg/100 but were low in       oxalate (0.02mg/100g and 0.03mg/100g), hydrogen cyanide (0.08mh/100g and             0.03mg/100g), saponin (0.01mg/100g and 0.01mg/100g), alkaloids (0.00mg/100g),            phytate (0.82mg/100g and 0.83mg/100g), trypsin (5.78mg/100g and 2.08mg/100g) and             phenol (0.31 and 0.51mg/100g). Tis87/0087 had the highest  carbohydrate (2.68%),           energy (355.80%), phytate (1.03mg/100g) and least protein (4.79%), fat (0.60%),calcium         (0.64mg/100g), vitamin C (30.36mg/100g)_, beta-carotene (0.30mg/100g) and tannin     (1.16mg/100g), Ex-igbarian was highest in vitamin B₁ (5.30mg/100g), E (0.49mg/100g),                   trypsin (13.18mg/100g) but lowest in phosphorus (22.02mg/100g), iron (0.05mg/100g)             and potassium (165.72mg/100g), Tis8164 had highest hydrogen cyanid (0.26mg/100g),             oxalate (0.12mg/100g and saponin (0.05mg/100g),  and lowest in total carotene     (1.59mg/100g), vitamin B₃ (0.35mg/100g)_,  and vitamin C (30.36mg/100g) and magnesium (0.27mg/100g). Peeling had a significant decrease (P<0.05) on the proximate,     minerals, beta-carotene and vitamin E. Oven drying significantly decreased all the             parameters except potassium, flavonoids and phenol that increased. Milling showed          significant decrease on, energy and fat and was not significantly affected on others.    Despite the losses experienced by these cultivars during flour production in some of the        physicochemical parameters analyzed, Umvspo3 and Umvspo1 had the highest values in         majority of the nutrients and least values of anti- nutrients analysed,   Therefore, it is             recommended to use orange fleshed sweet potatoes for flour production since they retain better amount of their nutrients after processing and peeling sweet potato roots in flour         production should be avoided.