动态高压微射流作用对膳食纤维结晶结构的影响

 利用N₂吸附法、X射线衍射、傅立叶红外光谱仪（FTIR）等手段，对动态高压微射流技术（Dynamic High Pressure Microfluidization，DHPM）处理前后膳食纤维的比表面积和结晶结构的变化进行表征，研究DHPM对膳食纤维结晶结构的影响。结果表明，经DHPM处理后，膳食纤维的比表面积显著高于未处理的原料膳食纤维（p<0.05）。在40~140 MPa压力区间，样品的比表面积随DHPM处理压力的升高而增加，处理压力为140  MPa时，达到最大值为2.887 5 m²/g。压力继续增大，微小颗粒间的重新聚集，使其对N₂的可及度减小，比表面积下降。X射线衍射结果显示，DHPM处理并没有使膳食纤维的晶型发生改变，为纤维素Ⅰ型。经DHPM处理后，样品表观结晶度显著减小，内部的有序度下降。处理压力越大样品的表观结晶度越小。FTIR光谱分析表明，DHPM处理会破坏膳食纤维内的部分氢键，处理压力越大，作用效果越明显。

Effect of Dynamic High Pressure Microfluidization on the Crystal Structure of Dietary Fiber

Differences in specific surface area and crystal structure between raw dietary fiber (DF) obtained from soybean and DF modified with dynamic high pressure microfluidization (DHPM) were analysis by nitrogen adsorption, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the specific surface area of DF was enlarged significantly (p<0.05) by DHPM treatment. The specific surface area of DF increased with the increase of  pressure in the range of 40-140 MPa, and the maximum specific surface area of DF was 2.887 5 m²/g. When the pressure went on increasing, the accessibility to N₂ tended to decrease because of the aggregation of micro particles.XRD confirmed that both raw DF and modified DF had cellulose Ⅰ crystal structure. After DHPM treatment the crystal form of DF was not changed, whereas the apparent crystallinity of DF was reduced. The higher the pressure was, the less the apparent crystallinity was. FTIR spectra showed that DHPM led to 2-OH…O-6 intramolecular hydrogen bond and β glycosidic linkage decreased, and as the pressure increased the effect became more obvious.