Biochemical Compositions, Functional Properties of Orange Fleshed Sweet Potato Varieties and Effect of Treatment on its Beta Carotene Retention

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Addis Ababa University


Vitamin A deficiency (VAD) is a public health problem in Ethiopia. It affects vision, growth, tissue differentiation and immune system. Orange-fleshed sweet potato varieties are known to contain high amount of β-carotene and other carotenoids. This study was designed to determine β-carotene retention, mineral composition, antinutrient level and functional properties of orange-fleshed sweet potato varieties. In order to compare β-carotene contents of different orange fleshed sweet potato varieties, to investigate the effect of treatment methods on β-carotene retention, orange-fleshed sweet potato varieties were collected from Hawassa Agricultural and Research Institute. The results showed that β-carotene contents were significantly affected by many factors, and this was demonstrated using the varietes of Kulfo and Tulla. β-carotene contents in orange-fleshed sweetpotatos Kulfo and Tulla grown in the same farming sites in the same area ranged from 400-334.05μg/g and 335.25-280μg/g fresh weight, respectively. Six treatment methods including boiling, steaming, microwave cooking, oven drying, sun drying and post steam-drying were simulated in the study to check their effects on the true retention of β-carotene. Compared to boiling, steaming resulted in much more loss of β-carotene and microwave cooking resulted in the biggest loss of β-carotene among the six treatment methods. The level of retention was significantly different (P<0.05) among treated Orange Fleshed Sweetpotato. The dietary Ca, Fe, Zn, and K contents of Kulfo and Tulla varieties respectively were Ca (22.14mg/100g, 18.78 mg/100g); Fe (20.83 mg/100g, 7.47 mg/100g); Zn (3.63 mg/100g, 1.23 mg/100g) and K (3064.68 mg/100g, 1469.13 mg/100g). Similarly phytate and tannin content of Kulfo and Tulla respectively were (432.10 mg/100g, 89.29 mg/100g) and (89.36 mg/100g, 40.02 mg/100g). The mineral composition and antinutrient content of the two varieties was significantly different (P<0.05). The functional properties were observed to have Bulk density (0.74 and o.62g/ml); Swelling index (161.1 and 138%); Water absorption capacity (253 and 212%); Oil absorption capacity (1.84 and 1.68ml) in both varieties respectively. Orange-fleshed sweet potato should be prepared for consumption, using methods that protect the loss of β-carotene content which helps orange-fleshed sweet potato as a staple food as well as a snack food for supplying vitamin A for both rural and urban populations. Key words: - Vitamin A Deficiency; β-carotene; Retention; Orange fleshed sweet ;potat;, boiling



Vitamin A Deficiency; β-carotene; Retention; Orange fleshed sweet potat; boiling