Study On The Relationship Of Quality Properties And Moisture State Of Wheat Flour

Water is the main component of food. Water content, distribution and the state of existence have significant effect on the processing characteristics, quality stability and preservation of food. Moisture migration, redistribution, the change of state, and the binding with protein, starch and other macromolecules are the key factors affecting the quality of wheat flour and the products of wheat flour. The relationship between quality properties and distribution of the moisture of flour from different systems, the effect of particle size distribution on moisture status and quality, the impact of the content of damaged starch and water addition amounts on relaxation properties of dough, and the inherent relationship between the change of moisture state during storage processing and quality of noodles were determined by NMR, as to explore the influence mechanism of moisture status on quality properties and provide theoretical basis for quality control, the results were as follow:1. Among the wheat milling streams, the change of bound water and middle water was small, and the change of moisture state was greater than the basic physical and chemical indicators. Among different wheat milling streams, relaxation time T21 had no significant difference, relaxation time T22 and T23 presented significant difference. In terms of proton density, A21?A22 and A23 all showed significant difference, among which, the coefficient variation of A23 was maximum while that of A21 was minimum. Between the front system and the later system, bound water had no significant difference, middle water and free water both presented significant difference. Moreover, the mean value of the later system was bigger than that of the front system. There was certain inherent correlation between the moisture of various existence state and quality properties.2. With the decreasing in particle size, water content of different wheat milling streams increased before decreased, protein content was trending downward, while starch content extended rising trend. Moreover, whiteness and damaged starch content increased gradually, but D50 and falling number presented the opposite trend. The quality indicators of system powder had significant difference in different particle size range. Relaxation time T21 and proton density A21 increased before decreased, and the mobility of proton became poor, T22?T23 and A23 showed a downward trend, while A22 was on the uptrend, relaxation properties of free water and particle size were positively correlated.3. With the rising in damaged starch content, the mobility of bound water became poor, while middle water presented the opposite trend, T21 and A21 of the dough presented declining trend, while T22 and A22 showed rising trend. Meanwhile, damaged starch content, relaxation time and proton density exhibited linear correlation to some extent. Beside, with the rise of water addition amounts, T21 and T22 increased gradually, when the water addition amount was below the optimum water absorption, bound water content increased rapidly. When exceeding the optimum water absorption proton, middle water contenct increased rapidly.4. With the increment of storage time, the water content, witness and springiness of fresh wet noodles gradually decreased, but the acidity and hardness increased. The cooking loss rate increased obviously and the water absorption rate decreased in general. Relaxation time T21 and T22 showed a downward trend and the mobility of proton became poor, bound water changed into middle water, A21 decreased gradually, A22 increased before decreased. Compared with storage in ambient temperature, the quality of fresh wet noodles was better maintained in frozen storage. The correlation analysis presented that there was a significant correlation between water state and the quality of fresh wet noodles during their storage.5. With the extension of storage time, the water content and cohesiveness of cooked noodles decreased, but the hardness and the cooking loss rate gradually increased. The springiness showed a downward trend after the first rise. T21, T22, A21 and A23 increased, but T23 and A22 decreased. Moreover, the bound water, middle water, free water transfromed each other. However, there was not a significant correlation between water content and the quality of fresh cooked noodles.Reheating contributed the fall in whiteness and taste of fresh cooked noodles.