Physicochemical properties and flour pasting profiles of popular sweet potato varieties from Kenya and Uganda

Abstract

Sweet potato varies in physicochemical properties as a result of inherent varietal makeup and agroecological zones where they are grown. Although pasting profiles of sweet potato flour can be used to determine their end-use in food processing, information on systematic evaluation of popular varieties in Kenya and Uganda is limited. Four orange-fleshed sweet potato varieties from Kenya and four common varieties from Uganda were evaluated for their physicochemical properties and for the pasting profiles of their flours. Results indicated significant variations (p< 0.01) in the attributes of the eight varieties. Orange fleshed varieties (OFV) had comparatively higher moisture, beta carotene, fat, and mineral contents but lower pasting profiles than the non-orange fleshed varieties (NOFV). The sodium/Potassium ratio of the eight varieties ranged from 0.16 to 0.5 and within <1 that is recommended. Calcium/magnesium ratios ranged from 1.11 to 2.09 and were above the required value of 1. OFV had calcium/phosphorous values above 2.00 while NOFV had values below 0.1 against the required >0.5. OFV had lower Peak viscosities (124-590cP) and cold paste viscosities (89.5-319cP) compared to 677-1060Cp (peak viscosities) and 438-800cP (cold paste viscosities) for NOFV. Positive correlations were recorded between flour pasting profiles and carbohydrates (r = 0.71 – 0.88), starch (r = 0.26 -0.52), phosphorous (r = 0.05 – 0.37), protein (r = 0.07 – 0.30) and fiber (r = 0.54 – 0.79). Sweet potato consumption can combat hidden hunger since it is rich in various minerals. The shelf life of sweet potato can be prolonged through processing into flour including blended flours for the production of high-quality food products.