Abstract:
The uses of composite flour in bread making are becoming more important as people become health conscious and accept the role of functional foods globally. The effect of partial replacement of wheat with 10% to 40% plantain flour and the subsequent effect of 1% to 3% gum arabic addition on composite bread quality attributes was investigated. It was hypothesized that wheat- plantain flour physicochemical properties did not differ from the control (100% wheat); and that neither substitution of 10% to 40% plantain in wheat nor incorporation of 1% to 3% gum arabic had an effect on quality attributes of wheat –plantain composite bread quality attributes. To test these hypotheses, several tests were done namely: proximate and mineral content analysis, farinograph test, analysis of other physical properties, specific loaf volume determination, pasting and texture profile analysis (TPA). The results indicated that the Kenyan plantain under study had noticeably higher protein (5.84±0.22%) and ash content (3.80± 1.42%) and a lower crude fat content (0.31± 0.01%) on dry basis. Moisture content, crude protein (CP) and crude fat (CF) decreased while carbohydrate content, crude fiber and ash content increased as the level of plantain substitution increased from 0 to 40%. Plantain substitution in wheat did not adversely alter the mineral content except for potassium which was significantly higher in the composites than the control at P≤ 0.05.The potassium levels in the wheat- plantain composite flour ranged between 29.74±3.53 to 62.59± 6.69 mg/ 100g compared to the control which had 17.17±0.39 mg/ 100g. The difference between the control and the composites was statistically significant (P≤ 0.05) at all levels of plantain incorporation for water-holding capacity (WHC), foaming capacity (FC), Emulsion capacity (EC) and bulk density (BD). All the four composites differed significantly from the control (P≤ 0.05) with respect to farinograph parameters namely: water absorption (WA), dough stability (DS), departure time (DT) and peak time (PT). Wheat- plantain composites produced dough that took longer than the control to breakdown thus stronger dough. Plantain composites had a higher peak viscosity which indicated that the composites had a higher swelling index than the wheat (control). The results indicated that low levels of plantain substitution may have no adverse effect on gluten functionality since composite’s bread volume did not differ significantly from the control (P> 0.05). Gum Arabic as used in this study was found to improve the bread’s textural qualities such as reducing bread hardness and chewiness and increasing bread springiness.
