Evaluation and utilization of starches from different sources in some baked products

Abstract

The objective of this study was to characterize and evaluate five starches from different local Sudanese Cereal Cultivars (wheat, sorghum, millet and rice), and from cassava and their use with wheat cultivar (Imam) and lentil flours for making biscuits and bread. Ratios of starch used in wheat flour for making bread and biscuits were 5, 10 and15% , and 10, 15 and 20% respectively, whereas ratios of lentil flour in wheat flour for making bread and biscuit was 5% and 10% respectively. Proximate composition, mineral content, functional properties and color were carried out for five starches. Flour characteristics and rheological properties were studied for wheat flour and wheat flour blends. The results indicated that the five starches were significantly (P≤0.05) different in their chemical composition and mineral content. Wheat and cassava starches were found to be most acidic (0.03mg/100g) compared to sorghum, millet and rice starches (0.05mg/100g). Analysis of variance indicated that there are highly significant (P≤0.05) differences among the five starches in their falling number, water retention capacity (44.44 to 122.20 ml/100g), fat absorption capacity (50.00 to 95.00ml/100g), gelatinization temperature, cold and hot viscosity and amylose content. On the other hand, wheat and cassava starches gave significantly (P≤0.05) higher bulk density (0.67 and 0.63 gm/ml). Rice starch showed significantly (P≤0.05) lowdispersibility (70%) compared to the other starches. Sorghum and cassava starches gave very strong gel, while wheat, millet and rice starches gave strong gel at 10% concentration. The results indicated that cassava starch was whiter compared to other starches (95.71%). Millet starch showed high gelatinization temperature and low amylose content. Addition of starches to the wheat blends resulted in increase in the falling number of wheat flour from 734.67 seconds to the range from 784.00 to 1079 seconds and significant (P≤0.05) decrease in wet gluten and gluten index. Water absorption decreased to the value range of 55.70 to 59.50% for the blends of 5%, 10%, and 15% wheat, sorghum and cassava starches blends and increased to 60.20% to 63.30% for rice starch blends. Addition of high percentage of starch results in low values of dough development time. The energy andthe extensibility of the dough of wheat flour decreased with addition of different starches percentages and the dough resistance to extension increased. Rice starch had the highest pasting temperature, gelatinization temperature and lower viscosity of amylograph. Pasting temperature increased in the blends, while gelatinization temperature and gelatinization maximum decreased. Addition of lentil flour to the blends resulted in increase of protein content of the blends in spite of presence of starch. Albumin and Globulin increased, while Glutenin and Gliadin decreased as a result of addition of starch and lentil flour in the blends. From the results it could be concluded that quality attributes of sensory evaluation of bread made from the flour blend was found to be very good in spite of low bread specific volume. Spread ratio of biscuits increased with the increase in the percentages of starch. In general, panelists preferred 15% rice starch blend biscuit being the best in all quality attributes of sensory evaluation.