Partial substitution of wheat flour with OFSP in bread making.

Abstract

Sweet potato(Ipomea batatas), is an important food, staple of many temperate countries and it is in fifth position among the most important crops in the developing countries in terms of economic value, seventh position for energy production and in seventh position after wheat, rice, maize, potato, barley and cassava in terms of production. The crop plays an important role in global food systems ranging from being a drought resistant crop to being rich in both micro and macro nutrients which are fundamental food requirements for increasing food security. Adding value to Orange Fleshed Sweet potato (OFSP) can increase the utilization of sweet potato in local confectionary industries. Therefore the purpose of this study was to determine the optimum level of substitution of wheat flour with SPF and SPP to produce a nutritious, acceptable and shelf stable bread. The dough of different percentages of SPP or SPF was prepared using straight dough method. Briefly, the dough was knead using an electric hard dough mixer for 10 minutes at medium speed and later proofing was carried out at 35oC for one hour. Baking carried out for 25-min at 220-250°C in an electrical oven. The loaves then were taken out of the tins, cooled at an ambient temperature for 1hr prior to sealing in polyethylene bag. The fleshly hygienically prepared SP bread of 20% substitution level was stored at room temperature while put in a polyethylene bag, the same way how shop attendants store them and monitored for moisture content, β-Carotene content, carbohydrate content and, fats and oils content change for the period of six days. The results showed; the sensory acceptability of OFSP bread increases as the level of substitution increases. The substitution level at 50% had the highest sensory acceptability but with low volume. The substitution level of 20% performed best in crumb structure, flavor, after taste and taste, the qualities that made this formulation/recipe unique compared to the other. This also made to be taken as the overall best formulation because of high substitution levels used and appealing physical qualities. During the period of six days, the moisture content and β-content of both OFSP bread and standard bread decreased significantly (p<0.05) while other components under study remained unchanged. Key words: Sweet potato puree, Bread, Baking, Sweet potato variety, Substitution levels.