Comparison of Three Methods to Determine the Degree of Substitution of Quinoa and Rice Starch Acetates, Propionates, and Butyrates: Direct Stoichiometry, FTIR, and 1H-NMR

Nabilah Abdul Hadi; Berthold Wiege; Sebastian Stabenau; Ali Marefati; Marilyn Rayner

doi:10.3390/foods9010083

Comparison of Three Methods to Determine the Degree of Substitution of Quinoa and Rice Starch Acetates, Propionates, and Butyrates: Direct Stoichiometry, FTIR, and ¹H-NMR

Foods. 2020 Jan 12;9(1):83. doi: 10.3390/foods9010083.

Authors

Nabilah Abdul Hadi^{1

2}, Berthold Wiege³, Sebastian Stabenau³, Ali Marefati¹, Marilyn Rayner¹

Affiliations

¹ Department of Food Technology, Engineering, and Nutrition, Lund University, SE 22100 Lund, Sweden.
² School of Food Science and Technology, University Malaysia Terengganu, Kuala Terengganu 21030, Terengganu, Malaysia.
³ Department of Safety and Cereals, Max Rubner-Institut, Federal Research Institute of Nutrition and Food, 32756 Detmold, Germany.

Abstract

Rice and quinoa starch esters were prepared by acylation using short-chain fatty acid anhydrides with different chain lengths (acetic, propionic, and butyric anhydride). A direct stoichiometric method based on the acylation reaction was used to determine the degree of substitution (DS) and acyl content (AC). In addition, Fourier-transform infrared spectroscopy (FTIR) was used to validate the conformational changes of acylated starch and ¹H-NMR was used as a DS reference method. DS by stoichiometric calculation was shown to be in agreement with FTIR and was comparable with DS obtained from Proton nuclear magnetic resonance (¹H-NMR). Based on this study, stoichiometric calculation allows rapid and direct determination of substitution levels and acyl content without the loss of samples, which provides efficiency and optimization of manufacturing procedures in producing the desired level of esterified starches.

Keywords: 1H-NMR; FTIR; degree of substitution; modified starch; short-chain fatty acid; stoichiometry.

Abstract

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