Characteristics of granular cold-water gelling starches of cereal grains and legumes prepared using liquid ammonia and ethanol

Starches of wheat, corn, smooth and wrinkled peas, and chickpeas were modified to a free-flowing powder of granular cold-water gelling (GCWG) starch using liquid ammonia and ethanol at 23degreesC and atmospheric pressure. Amylose content of starches was 26.3% in wheat, 27.1% in corn, 35.4% in chickpeas, 43.2% in smooth peas, and 79.9% in wrinkled peas. The modified starches remained in granular form with an increased number of grooves and fissures on the surface of the granules compared with native starch, while the crystallinity was mostly lost, as shown by X-ray diffractograms and DSC endothermic enthalpies. Pasting viscosity of modified starches at 23degreesC was 171 BU and 305 BU in wheat and corn, respectively, and much higher in legume starches, ranging from 545 BU to 814 BU. Viscosities of modified legume starches at 23degreesC were at least twice as high as those of native starches determined at 92.5degreesC. Swelling power of modified starches at 23degreesC ranged from 8.7 g/g to 15.3 g/g, while swelling power of native starches heated to 92.5degreesC ranged from 4.8 g/g to 16.0 g/g. GCWG starches exhibited higher dextrose equivalent (DE) values of enzymatic hydrolysis, ranging from 25.2 to 27.0 compared with native starches (1.5-2.9). Modified starches from wheat, corn, smooth peas, and chickpeas formed weak gels without heat treatment and experienced no changes in gel hardness during storage, while native starch gets formed by heat treatment showed an increase in hardness by 1.1-7.5 N during 96 hr of storage at 4degreesC.