该研究以麦麸为原料，采用酶法提取不溶性膳食纤维（IDF），分别探究碱性蛋白酶和α-淀粉酶的用量和酶解时间对蛋白质和淀粉水解程度的影响，对IDF的提取条件进行优化，并对麦麸IDF的结构特征和理化性质进行研究。结果表明，碱性蛋白酶和α-淀粉酶用量分别为4 000 U/g麦麸和140 U/g麦麸，酶解时间分别为2 h时，得到麦麸IDF的纯度达82.56%。采用扫描电子显微镜、X-射线衍射仪和傅里叶变换红外光谱对麦麸IDF的结构进行表征，发现经酶法提取后的麦麸IDF具有明显孔洞及裂缝，表现出典型的I型纤维素结晶结构，主要组分包括纤维素、木质素和半纤维素。对麦麸IDF理化性质的研究发现，与麦麸相比，麦麸IDF的持水力（3.82 g/g）、膨胀度（2.59 mL/g）和持油性（1.78 g/g）均得到改善，说明其具有用于面制品、凝胶制品、肉制品等提高产品稳定性和感官品质的潜力。此外，麦麸IDF的亚硝酸根离子清除率达到95.63%，说明其可作为功能性食品配料降低亚硝酸盐对人体健康的影响。研究结果将对提高麦麸的附加值，及麦麸IDF在高品质健康食品中的应用提供指导。

Insoluble dietary fiber (IDF) was extracted from wheat bran using the enzymatic method. The effects of dosages of alkaline protease and α-amylase as well as the duration of enzymolysis on the degrees of hydrolysis of protein and starch were investigated. The extraction conditions of IDF were optimized. The structure and physicochemical properties of IDF from wheat bran were studied. At the alkaline protease and α-amylase dosages of 4 000 U/g and 140 U/g, respectively, and the duration of enzymolysis of 2 h for each enzyme, the purity of extracted wheat bran IDF was 82.56%. The structure of wheat bran IDF was characterized by scanning electron microscopy, X-ray diffractometry, and Fourier transform infrared spectroscopy. The particles of extracted wheat bran IDF had holes and cracks on the surface, their crystalline structure was a typical type I cellulose crystalline structure, and the main components of wheat bran IDF were cellulose, lignin, and hemicellulose. The obtained wheat bran IDF showed higher water holding capacity (3.82 g/g), swelling power (2.59 mL/g), and oil holding capacity (1.78 g/g) than wheat bran, suggesting its potential application in flour products, gelled foods, and meat products to improve the stability and sensory qualities of the products. In addition, the nitrite ion clearance ability of wheat bran IDF reached 95.63%, implying its applicability as a functional ingredient in foods for reducing the negative impacts of nitrites on human health. These results provide guidance for improving the added value of wheat bran and for the application of wheat bran IDF in high-quality healthy foods.

国家自然科学基金资助项目（31801490）