Effect Of Physical Modification On The Properties Of Color Wheat Bran And The Development Of Lipid-Lowering Mixing Powder

The nutrition and healthy function of color wheat bran is higher than that of common wheat bran.In order to improve its utilization rate and meet the requirements of high quality fiber.In this study,the conditions of improving SDF（Soluble Dietary Fiber）yield by three kinds of physical modification methods,including ultra-fine grinding,extrusion expansion and ultra-high pressure,were studied.The changes of basic components,physical and chemical characteristics,processing characteristics,functional characteristics and microstructure of wheat bran before and after modification were compared,and the better way was selected to apply to the research and development of lipid-lowering mixing powder.The main results are as follows:（1）Determination of physical modification conditions.Taking the SDF yield of color wheat bran as the index,the optimum conditions of physical modification were determined through the optimization test with the ratio of ultra-high pressure material to liquid 1:15,holding pressure for 15 min,and ultra-high pressure for 300 MPa,under which SDF yield was17.72%.The highest yield of SDF was 17.54%with superfine grinding to 200 mesh.The conditions of extrusion were as the follows:the water content of the material was 16%,the screw speed was 350 r/min,the extrusion temperature was 150 ^oC,SDF yield was 16.17%.SDF yield of the three methods is 1.70,1.67 and 1.46 times of that of the original color wheat bran,respectively.（2）Analysis of the basic components,physical and chemical properties of color wheat bran before and after modification.The content of water,fat and ash of wheat bran decreased,and the highest content of flavonoids and polyphenols was found in the ultra-fine comminuted wheat bran,which were 1.50 and 1.47 times of the original color wheat bran,respectively.The highest water holding capacity,oil holding capacity and expansion of ultra-high pressure wheat bran were 2.92 g/g,1.49 g/g and 2.41 g/mL,respectively,followed by ultra-fine comminution of wheat bran;ultra-fine comminution can significantly improve the color of wheat bran powder.After modification,the cation exchange capacity of wheat bran was improved,the scavenging effect of wheat bran on NO₂^-mainly occurred in the gastric environment,and ultra-fine comminution,ultra-high pressure,extrusion and expansion of wheat bran were 80%,77%,68%higher than the original samples.（3）Comparative analysis of processing characteristics of color wheat bran before and after modification.The solubility and dispersibility of wheat bran treated by three physical methods were improved,and the order of solubility from high to low was ultra-fine crushing,ultra-high pressure and extruding expanded wheat bran,which were 2.16,1.41 and 0.55 times of the original samples,respectively.The dispersibility of ultra-fine comminuted wheat bran was 6.59%,followed by ultra-high pressure wheat bran 7.66%,extruded wheat bran 7.81%,and original wheat bran 11%.The modified wheat bran had better thermostability.（4）Comparative analysis of functional characteristics of color wheat bran before and after modification.The DPPH,ABTS,·OH scavenging capacity and reducing power of water extract and alcohol extract from the modified wheat bran were significantly improved,among which the ultra-high pressure wheat bran was the best,followed by ultra-high pressure wheat bran.The combination of wheat bran with cholesterol was mainly in the simulated small intestine environment,and the ultra-fine comminuted wheat bran had a good lipid-lowering effect.The maximum cholesterol adsorption capacity of ultra-fine wheat bran was 16.21 mg/g,the sodium cholate adsorption capacity was 20.10 mg/g,and the simulated sodium cholate binding capacity in vitro was 14.11%,which were 0.33,0.04,0.20 times of ultra-high pressure wheat bran,0.60,0.15,0.57 times of extruded wheat bran,respectively.（5）Comparative analysis of the microstructure of color wheat bran before and after modification.The results of SEM showed that the ultra-fine comminution reduced the size of wheat bran,increased the specific surface area of wheat bran,but the ultra-high pressure and extrusion made the wheat bran more porous.The infrared spectrum of wheat bran before and after modification was similar,but the peak intensity and area of some characteristic absorption peaks were slightly changed,and the modified treatment did not change the functional group structure of wheat bran.X-ray diffraction showed that there was no new crystal zone in the modified wheat bran,the main diffraction peak was close,and the crystal strength was improved.（6）Development of lipid-lowering mixing powder for superfine smashing color wheat bran.The ultra-fine wheat bran powder with good functional,physical and chemical properties and processing properties was used in the development of mixing powder.The best formula was determined as 20%skimmed milk powder,12%sorbitol,and 9%jujube powder with sensory evaluation water holding capacity,oil holding capacity and expansion as indices and the best supplement formula was 2.4%microcrystalline cellulose,4%soluble soybean polysaccharide 4%,and silica 1.4%;with sensory evaluation and preparation stability as indices.It was found that the sensory,physicochemical and microbiological indexes of the products met the standards;compared with the similar wheat bran products in the market,the mixing powder made in the laboratory has a good sensory quality,taste,good rheological properties and lipid-lowering activity,low sugar content,and a SDF content up to 17.81%.