关键词: 核磁共振, 磁共振成像技术, 面团, 吸水率, 搅拌时间

Abstract: The relationship between gluten contents,stiring,hydration,and the state of water in flour dough were studied with NMR and MRI techniques. The state of water was measured using spin-lattice and spin-spin relaxation times,or T1 and T2 respectively. In stiring period,T2* values (or the apparent T2 obtained with single 90 degree pulse sequence) and the corresponding proton density decreased rapidly initially with increasing stiring time,indicating that the bulk water added to the flour was rapidly incorporated into the flour,hydrating the proteins and other components in the flour. The curve between T2* and mixing time showed the formation process of dough that can direct the optimal stiring time in dough. Stiring time was also affected by moisture content,however,there was no different among different content of gluten. The date shows that the stable time was different with the different of gluten content in dough,the higher the gluten,the longer stable time. Higher temperature increased the formation of dough. The water mobility was also found to be affected by stiring temperature. With two component fitting,it was found that T1 values and T1 amplitudes increased with increasing moisture content and decreasing gluten content,also found that there was solid relationship between T1 and water absorption in flour which decided the optimal moisture content in different gluten flour,with the gluten content of 25.4%,30.4%,35.8% in flour the optimal moisture absorption is 55%,57.5% and 60% respectively.

Key words: NMR, MRI, dough, absorbability, stirring time