A comparison of equilibrated lipid water systems and the effect of added lecithin on dough rheology of flour milling-streams

The lipid part of four wheat flour milling streams was extracted by ethanol. The flours were two spring wheats and two winter wheats, where one of each spring and winter wheats were obtained from the reduction-roll system and the other one from the break-roll system. Equilibrated lipid water mixtures were prepared and centrifuged to distinguish between non-polar and polar lipids. The lipids interacting with water were investigated in the microscope under polarised light to establish the presence of the lamellar liquid-crystalline phase. The stress relaxation behaviour of flour water doughs and doughs made with lamellar lecithin added were also studied. The largest amount of lipids able to form the lamellar liquid-crystalline phase was recovered for the winter wheat from the reduction milling-stream. The corresponding spring wheat also formed the lamellar phase, while the break flours did not. A large amount of oil phase was obtained from the two break flours. The rheological parameters increased to the same value for the two break flours and the two reduction flours when lecithin was added. This suggests that a flour containing protein and lipids of approximately the same quality will be improved to the same extent when lamellar lecithin is added. © SCI 1998.