Production and Quality Evaluation of Flour Produced From Two Varieties of Sweet Potato

Abstract:

This study investigated the production and quality evaluation of flour from two sweet potato varieties (cream-fleshed and purple-fleshed sweet potato) subjected to different processing treatments: blanching, sulphiting, and untreated as a control sample. The resulting flour samples were analyzed for functional, pasting, color, proximate, mineral, and vitamin properties using standard analytical methods. Significant differences (p<.05) were observed among the flour samples. Results of functional properties showed that the bulk density of sample SPSF (Sulphited purple fleshed sweet potato flour) had the lowest bulk density of 0.73 g/ml and the least gelation capacity of 6.00%. Sample SPSF (Sulphited purple fleshed sweet potato flour) recorded higher values in water absorption capacity (2.41 g/g), oil absorption capacity (1.72 g/g), and swelling capacity (5.70 %). Sample RFCS (Raw cream fleshed sweet potato flour) showed the least dispersibility of 69.15%. The results of the pasting properties showed that sample PSRF (Untreated purple-fleshed sweet potato flour) showed the highest peak viscosity (319 RVU), Trough viscosity (219.00 RVU), breakdown (100.00 RVU), and final viscosity (386.00 RVU), respectively. Sample SPSF (Sulphited purple-fleshed sweet potato flour) recorded the lowest setback (148.00 RVU). Color evaluation indicated higher lightness values in cream-fleshed sweet potato flour samples (86.42 – 89.76) compared to purple-fleshed samples (62.54 – 69.45). Moisture content ranged between 8.93 – 9.81%, with sample SPSF (Sulphited purple-fleshed sweet potato flour) recorded as the lowest, while carbohydrate content varied between 80.09 and 81.93%. Untreated purple-fleshed sweet potato flours generally exhibited higher protein, ash, fiber, and mineral contents for calcium (46.10 – 48.50 mg/100 g), potassium (319.20 – 350.50 mg/100 g), and phosphorus (58.30 – 62.50 mg/100 g). Furthermore, untreated purple-fleshed flour recorded the highest vitamin A (465.50 mg/100 g) and vitamin C (24.03 mg/100 g) contents. The study showed that both sweet potato varieties possess desirable nutritional and functional attributes, with purple-fleshed sweet potato flour, particularly the untreated sample, exhibiting superior nutritional quality. Therefore, sweet potato flour has considerable potential for application in food product development and nutritional enhancement of cereal-based foods.