Effect of Sweet Potato Leaf and Stem Addition on Dough Properties and Bread Quality

Abstract

Sweet potato leaf and stem, rich in dietary fibre, were used to study their effects on properties of dough and toast bread. Dried and pulverised leaf and stem were separately added at 5, 10 and 15% substitution level. Rheological properties, color and texture of the bread were measured by a farinograph, colorimeter and texture profile analyser, respectively. Results showed water absorption and maximum tolerance index of the dough increased with increasing amount of leaf and stem, while development time, stability and time to breakdown decreased. Bread crumb with substituted leaf was darker than that with substituted stem, and both were significantly darker than the control. Texture analysis indicated little changes in adhesiveness, but hardness and chewiness of bread at the substitution level above 5% were significantly higher than those of the control. Sensory evaluation showed a tendency that the taste, texture, colour, flavour and overall acceptability of bread substituted with 5% stem were better than those with 5% leaf, and comparable to those of the control.