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Granular Cold Water Gelling Starch Prepared from Chickpea Starch Using Liquid Ammonia and Ethanol

¹Graduate research assistant, late associate professor, and assistant professor, respectively, Department of Food Science & Human Nutrition and IMPACT, Washington State University, Pullman, WA 99164-6376. ²Corresponding author. E-mail: bbaik@wsu.edu Phone: 509-335-8230. Fax: 509-553-4815.

Granular cold water gelling (GCWG) starch was obtained by treatment of native chickpea starch with liquid ammonia at low temperature and atmospheric pressure. A free-flowing powder of the gelatinized starch granules was produced by adding ethanol to the mixture of starch and liquid ammonia. Four ratios of liquid ammonia to starch (A/S) (2:1, 4:1, 6:1 and 8:1) and four ratios of starch ethanol (S/E) (1:1, 1:2, 1:3 and 1:4) were tested for production of GCWG starch. Homogenous mixtures of liquid ammonia and starch granules appeared when the A/S ratio was >4:1. Treating starch with a 4:1:3 ammonia-starch-ethanol (A/S/E) ratio on a w/w/v basis resulted in a free-flowing powder of gelatinized starch, that formed a gel on addition of water at 23°C. Differential scanning calorimetry (DSC) thermograms of the GCWG starch, regardless of A/S/E ratio, displayed enthalpy values of 2.2–3.1 J/g compared with 15.5 J/g for native starch, indicating disappearance of crystallinity due to modification.