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,Ali Marefati,Berthold Wiege,Marilyn Rayner,Sebastian Stabenau

doi:10.3390/foods9010083

Nabilah Abdul Hadi, Ali Marefati + Show 3 more

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https://doi.org/10.3390/foods9010083

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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.

Highlights

Starch is one of the major carbohydrates in the biosphere and the main source of energy in green plants
The amylose contents of rice and quinoa starches used in this study were determined previously [3], which revealed that rice starch has low amylose content (4.43% ± 0.78)
The acylation and values obtained in this way were developed by using stoichiometric calculations

Summary

Introduction

Starch is one of the major carbohydrates in the biosphere and the main source of energy in green plants. It is found as granules in grains, tubers, roots, leaves, fruits, and stems. Starch is composed of two main macromolecules, amylose and amylopectin. Starch has gained attention from academic researchers and the industry as a food-grade ingredient due to multiple functionalities including the ability to act as emulsifiers in Pickering emulsions [4,5] as well as in the pharmaceutical area for drug delivery and encapsulation [6,7,8].

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