Effect Of Wheat Lipids On The Physicochemical Characteristics And End-use Quality Of Wheat Flour

Six wheat samples, Zhengmai004, Nongda211 (Wheat with weak-strength gluten), Hahong (Wheat with middle-strength gluten), Zimai, Zhengmai366, Shiluan (Wheat with strong-strength gluten), and their defatted flours, obtained after lipids were extracted by chloroform, were used in this research to investigate the function of lipid on physicochemical properties, Mantou and noodle quality of wheat flour.Microstructure of the flour particles, fermented dough, steamed and raw noodles of these samples were studied by SEM.Contrasted with the untreated sample, defatted flour had a higher protein and wet gluten content; the defatted flour had more single starch granules, but decreased the falling number of wheat flour. The defatted flour began to paste at a lower temperature and need a longer time to reach the peak viscosity according to RVA result. The same conclusion could be drawn from thermal test with DSC which indicated that defatted sample required more enthalpy to be gelatinized.The defatted flour had longer pasting peak time, higher peak and hold viscosity, lower setback and breakdown than those of the control.Defatting treatment affected the farinograph properties of strong gluten wheat flours much more than the other samples.The water absorption and dough development time increased but dough stability and farinograph quality number decreased significantly by lipid extraction.The Mantou-making test showed that the volume, the specific volume and wide/high increased for Mantou made from defatted wheat flour whith weak gluten.The cell number of steam-bread increased.The defatted flour had bigger area of cell and longer diameter.Hardness, Chewiness, Gumminess and Absolute value of Adhesiveness decreased for the steam-bread made from defatted flour with weak gluten, but Resilience increased. The middle and strong gluten flour defatting sample had the opposite perform compares with weak gluten wheat flour. The staling of steam bread upon storage can not be restrained but can be retarded effectively with lipid of flour. Cooked noodle had a higher Hardness, Chewiness Gumminess, absolute value of Adhesiveness, Firmness and Work of Shear for defatted wheat flour, the lossed materials increased and need shorter time to cooked noodles.After lipid was extracted from wheat flour with chloroform, there were more single starch granules and smaller aggregative particles which endued a better flowing quality to flour.Fermented dough had many gas cells, the gas cell smaller and wall thicker in fermented dough maded from flour with weak gluten. Inside wall of gas cell had more"hole", the protein embrance inflating to the breakage, bigger and thicker, inside wall of gas cell starch granules embedded into continous and well developed the gluten maxtri.The internal structure of noodles made from control wheat flour was firm and compact, the protein and the starch combined closely.Internal structure of noodles made from defatted wheat flour show that protein and starch granule international was loosened, discontinuous, especially the defatted flour with strong gluten, the starch granule exposed from the protein network, the protein becomes the thin embrane and between the starch granule.These experiments demonstrated that lipid have different effects on wheat flour with different gulten. The lipid may play a more important role on protein-starch matrix in dough and could influence physicochemical properties, rheological properties food-making quality of wheat flour.