Jeraci J L, Lewis B A, Van Soest P J, Robertson J B
Cornell University, Division of Nutritional Sciences, Ithaca, NY 14853.
J Assoc Off Anal Chem. 1989 Jul-Aug;72(4):677-81.
A method that uses urea and enzymes for determination of total dietary fiber (TDF) in foods has been developed and compared with the AOAC enzymatic-gravimetric method (43.A14-43.A20). In the evaluation, results for crude protein and ash contamination were higher by the AOAC method, particularly for samples that form gels during ethanol precipitation. The new urea enzymatic dialysis (UED) method quantitatively recovered, with less variation, more of the purified and semipurified dietary fiber products. TDF recoveries for carboxymethylcellulose and locust bean gum were 98% (SD 3.3) and 95% (SD 6.1) by the AOAC method and 99% (SD 1.0) and 100% (SD 0.6) by the UED method, respectively. The UED method was the more effective in removing starch. For kale samples, starch recovery was 3.5 and 0.2% from TDF residues obtained using the AOAC and UED methods, respectively. Differences were not significant among replicate values for determination of TDF in foods by the UED method (P greater than 0.01). Preliminary studies suggest that the new method can separately determine soluble and insoluble dietary fiber. The data indicate that the UED method is more precise and accurate than the AOAC method.
已开发出一种使用尿素和酶来测定食品中总膳食纤维（TDF）的方法，并将其与美国官方分析化学师协会（AOAC）的酶重量法（43.A14 - 43.A20）进行了比较。在评估中，AOAC方法测定的粗蛋白和灰分污染结果更高，特别是对于在乙醇沉淀过程中形成凝胶的样品。新的尿素酶透析（UED）方法能更定量地回收纯化和半纯化膳食纤维产品，且变异较小。AOAC方法测定羧甲基纤维素和刺槐豆胶的TDF回收率分别为98%（标准差3.3）和95%（标准差6.1），而UED方法分别为99%（标准差1.0）和100%（标准差0.6）。UED方法在去除淀粉方面更有效。对于羽衣甘蓝样品，使用AOAC和UED方法从TDF残渣中回收的淀粉分别为3.5%和0.2%。采用UED方法测定食品中TDF的重复值之间差异不显著（P大于0.01）。初步研究表明，新方法可以分别测定可溶性和不溶性膳食纤维。数据表明，UED方法比AOAC方法更精确、准确。
