Production of bread from blends of sorghum flour and gelatinized cassava starch

Abstract

Low specific volume yeast leavened bread was prepared from blends containing sorghum flour, raw and gelatinized cassava starch. Cassava starch was gelatinized in 90% distilled water by boiling for 4 min. The starch paste was cooled to 30'C and mixed with sorghum flour, sugar (8%). dry yeast (2%), salt (2%) and raw cassava starch to develop a batter. The batter was scaled (200 g), fermented at 300C and 90% RH for 40 min and baked at 192'C for 20 min. Gelatinized starch enhanced batter cohesiveness and viscosity, while raw cassava starch improved the crumb. Sorghum-cassava bread had greater loaf volume and significantly better crumb structure than sorghum bread. Sorghum flours free of black specks, with fine particle size distribution produced the best bread. Dorado flour produced the best loaf, ATx630*Tx435 flour produced bread with lower loaf volume and a sticky crumb, and waxy flour produced unacceptable bread with wet, sticky crumb and low loaf volume. Amylose content was 25.6, 20.8, and 4.1%, respectively. The sorghum flours with reduced amylose content had poor bread quality, suggesting that amylose may play an important role in breadmaking quality of sorghum cassava breads. Freshly baked sorghum-cassava breads had acceptable texture and flavor; a high staling rate shortened their freshness. Antistaling additives can retard staling and prolong the freshness of sorghum-cassava bread. Shortening (1%) and succinylate monoglycerides (SMG, 1%) increased loaf volume, and improved crumb structure and softness, but caused a rancid off-flavor. Glycerol and sodium stearoyl-2-lactylate did not increase bread volume and had no effect on crumb properties. Sorghum flours had significantly different pasting properties. The nonwaxy had the highest peak viscosity and the greatest setback viscosity. Shortening (1%) and 1% SMG retarded the onset of viscosity and increased the time required to reach peak viscosity. Nonwheat yeast leavened bread can be made with fine sorghum flour when gelatinized cassava starch is used to provide a continuous network to disperse the sorghum flour. The coarse grain bread can be sliced and consumed similar to wheat bread, although it stales rapidly.