PRODUCTS FROM WHEAT-PEARL MILLET FLOUR SUBSTITUTED WITH SWEET POTATO PEELS

Abstract

Twenty percent Pure Pearl Millet Flour (PPMF) contained in wheat-pearl millet composite flour was substituted with Pure Sweet Potato Peels Flour (PSPPF) ranging from 0 to 15%. Proximate compositions and dietary fibre contents of PPMF, PSPPF and flour blend formulations were investigated. Proximate compositions (%) showed that PPMF (9.9% and 80.4%) was significantly (p˂0.05) higher than PSPPF (4.5% and 69.8%) in protein and carbohydrate contents respectively. Among the flour blend formulations, 5% pearl millet and 15% sweet potato peel flour wheat flour substitution (PM5SP15) and 20% pearl millet and 0% sweet potato peel flour wheat flour substitution (PM20SP0) had the highest (16.1% and 9.2%) and the lowest (12.0% and 3.3%) Total Dietary Fibre (TDF) and Insoluble Dietary Fibre (IDF) respectively. Thirty-six phenolic compounds consisting of hydroxycinnamic acids, hydroxylbenzoic acids and non-anthocyanin flavonoids were identified in PSPPF. Total phenol Content (TPC) was higher in PSPPF than PPMF, whereas the highest (9.5 mg/g GAE) and the lowest (6.9 mg/g GAE) values in the flour blends were PM5SP15 and PM20SP0 respectively. The highest value for specific volume of bread (3.95 cm3/g) was observed in 5% sweet potato peel substitution (PM15SP5) while the lowest value (3.24 cm3/g) was recorded in 0% substitution (PM20SP0). Cakes produced with PM15SP5 showed highest specific volume, while PM20SP0 had lowest specific volume. Instrumental textural analysis of cakes showed that cohesiveness and resilience values of PM20SP0 cake was the highest but with no significant (P˃0.05) difference with PM15SP5. The mean sensory scores showed no significant difference in texture and overall acceptability of bread baked from PM20SP0 and PM15SP5, whereas the flavour of the latter was significantly (p˂0.05) rated higher than other formulations. Firmness and overall acceptability of cake baked from PM15SP5 was mostly preferred by the panelists but with no significant (p˃0.05) difference with cake produced from PM20SP0.