New H-1 NMR Procedure for the Characterization of Native and Modified Food-Grade Starches

作者：Tizzotti Morgan J; Sweedman Michael C; Tang Daniel; Schaefer Christian; Gilbert Robert G^*

来源：Journal of Agricultural and Food Chemistry, 2011, 59(13): 6913-6919.

DOI：10.1021/jf201209z

• starch
• NMR characterization
• branching degree
• degree of substitution

A novel, fast, and straightforward procedure is presented for the characterization of starch (the largest energy component in food) and modified starches (such as octenyl succinic anhydride (OSA)-modified starches used as a dispersing agent in the food industry). The method uses H-1 NMR to measure the degree of branching and also, for modified starches, the degree of chemical substitution. The substrate is dissolved in dimethyl-d(6) sulfoxide; addition of a very low amount of deuterated trifluoroacetic acid (d(1)-TFA) to the medium gives rise to a shift to high frequency of the exchangeable protons of the starch hydroxyl groups, leading to a clear and well-defined H-1 NMR spectrum, which provides an improved way to determine the degrees of both branching and chemical substitution. Measurements of the size and molecular weight distributions by multiple-detector size exclusion chromatography show that degradation by TFA does not affect the accuracy of the method.

• 出版日期2011-7-13