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This study evaluated the proximate and functional properties of the flour blends of orange fleshed sweet potato
(OFSP) and pigeon pea and their extrudates. Flours from two varieties [TIS 8164 (OFSPF1) and NRS P/05/022
(OFSPF2)] were individually substituted with pigeon pea flour (PPF) at 0%, 10%, 20%, 30%, 40% and 50% levels.
The flour blends, adjusted to moisture content of about 55%, were extruded using a single screw laboratory extruder
at 110 rpm and 100 oC. The flour blends and extruded products were analysed for proximate composition and
functional properties. There were significant (p < 0.05) differences in the proximate composition of the flour blends
with 50% PPF-substituted flour having the highest contents of protein, fat, crude fibre and swelling power (at 70
oC)for both OFSPF1 and OFSPF2. OFSPF2 recorded higher values for protein, fat, ash, and crude fibre than
OFSPF1. There were significant (p < 0.05) differences in the functional properties of the flour blends and extrudates.
Swelling power (at 70 oC)of the flour blends increased as the level of PPF increased for both varieties of OFSP.
Swelling index (at 90 oC), water absorption index and bulk density of extrudates decreased as PPF increased for both
varieties. Flour blends and extrudates from OFSPF1 had higher values for moisture, carbohydrates and wettability
than OFSP2.
Variety of OFSP influenced the proximate composition and functional properties of the OFSPF-PPF flour blends and
extrudates.
Keywords: Orange fleshed sweet potato, pigeon pea, functional properties, proximate composition, extrusion
cooking, cooking,