Construction Of Starch-Lipid Complex And Its Effect On Flour Products

To explore the effects of lipids with different molecular structures and different treatment methods on the formation and physico-chemical properties of wheat starch-lipid complex,wheat starch was used as raw material and the formation and anti-digestion mechanism of the complex were preliminarily discussed through crystallization structure,thermodynamic properties and in-vitro digestion experiments in this paper.Then,to study the formation of starch-lipid complex in the production of flour products,the starch-lipid complex was applied to the production of noodles,Chinese steamed bread and bread;and the formation and effect of starch-lipids complex on physico-chemical properties of flour products were also investigated.The effects of lipids with different molecular structures(fatty acids LA and SA;glycerides GML and GMS)and four treatment methods(common hydrothermal,pullulanase debranch,ultrasound and high pressure treatment)on the physico-chemical properties of wheat starch-lipid complex were studied.The results showed that the crystal structure was transformed from A-type to V-type with the formation of starch-lipid complex.The thermodynamic properties showed that the starch-lipid complex formed between wheat starch and lipid with short carbon chain had a higher enthalpy.In addition,the crystal structure showed that pullulanase debranch treatment was more likely to promote the interaction between amylose and ligand to form complex,which was attributed to the better dispersion of short chain lipid in starch paste and the increase of amylose content.The effects of lipids with different molecular structure(fatty acids LA and SA;glycerides GML and GMS)on the formation and physicochemical properties of starch-lipid complex was studied in wheat flour during noodles cooking.The effect of gluten protein in wheat flour on the formation of starch-lipid complex had also been proved.Compared with the common hydrothermal starch system,the V-type crystal peak of the samples with gluten protein became sharper,and the infrared spectrum showed that there was only protein characteristic peak increased with the addition of gluten protein,which indicated that gluten protein could promote the formation of starch-lipid complex with physical interaction.The crystallization peak of noodles was obviously weaker than that of starch system,which may be attributed to the limited boiling time and the compact lamellar structure of noodles,which hindered the absorption of water and the release of amylose.However,the anti-digestion ability of noodles was significantly enhanced.Lipids were applied to the production of steamed bread in the same proportion.The effect of lipid with different molecular structure on the formation of starch-lipid complex during steamed bread making and the effect of complex on the hydrolysis degree of steamed bread in vitro were investigated.The results showed that the crystal structure of the steamed bread with lipids transformed into V-type,the resistant to digestive enzymes of starch-lipid complex in steamed bread was enhanced.But the sharpness of the peak was much weaker than that of starch and noodles system,and the reason could be attributed to the fact that the water content of steamed bread was not enough and the starch granules did not break completely.Therefore,there was a little complex formed.Lipids were applied to the production of steamed bread in the same proportion,but there was little starch-lipid complex formed in the process of bread making,which may be due to the destruction of the structure of the complex by high temperature baking.Therefore,it is not feasible to apply starch-lipid complex during the baking process.