Li B W
U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Food Composition Laboratory, MD 20705, USA.
J AOAC Int. 1996 May-Jun;79(3):718-23.
A general scheme has been developed to determine sugars, starches, and total dietary fiber (TDF) in half-gram freeze-dried subsamples of various foods (or wet samples containing about 0.5 g dry matter). Duplicate subsamples are extracted for free sugars with 80% methanol, dried, derivatized to their trimethylsilylated oximes or ethers, and quantitated by gas-liquid chromatography (GLC). Residues after 80% methanol extraction are incubated with a solution containing amyloglucosidase in acetate buffer. Hydrolyzates are centrifuged, and duplicate aliquots are removed for glucose determination by GLC. Starch content is calculated as glucose (g/100 g) x 0.9. Remaining hydrolyzates are diluted with 4 volumes of 95% ethanol, left at room temperature for 1 h, and then filtered through glass crucibles matted with Celite filter aid. The weight of dry residues are corrected for residual crude protein and ash, and the resulting values are taken to be the TDF content of a sample. A variety of high-consumption foods selected by the Nutrient Data Laboratory of the Agricultural Research Service were analyzed for carbohydrate fractions by this method. Values for total sugar and dietary fiber were compared with those obtained by a commercial laboratory using different methods.
已制定了一种通用方案，用于测定各种食品半克冻干子样本（或含约0.5克干物质的湿样本）中的糖类、淀粉和总膳食纤维（TDF）。取两份重复的子样本，用80%甲醇提取游离糖，干燥后衍生化为三甲基硅烷基肟或醚，然后通过气液色谱法（GLC）进行定量分析。用80%甲醇提取后的残渣与含有糖化酶的醋酸盐缓冲液一起孵育。水解产物进行离心，取两份重复的等分试样通过GLC测定葡萄糖含量。淀粉含量按葡萄糖（克/100克）×0.9计算。将剩余的水解产物用4倍体积的95%乙醇稀释，室温放置1小时，然后通过铺有硅藻土助滤剂的玻璃坩埚过滤。对干残渣的重量进行粗蛋白和灰分残留校正，所得值即为样品的TDF含量。美国农业部农业研究局营养数据实验室选择的多种高消费食品用此方法分析了碳水化合物组分。将总糖和膳食纤维的值与商业实验室使用不同方法获得的值进行比较。
