Physicochemical characterization of starches from Amaranthus cruentus grains
1998
Hoover, R. | Sinnott, A.W. | Perera, C.
The physicochemical properties of starches isolated from three cultivars (Mexican, African and A200D) of Amaranthus cruentus grains were studied. The yield of starch was in the range 29.0 - 38.3 % on a whole grain basis. The starch granules were polygonal with smooth surfaces. The granule size was in the range 0.75 - 1.5 micron-m for all three cultivars. The free, bound and total starch lipids ranged from 0.05 to 0.07 %, from 0.16 to 0.28 and from 0.20 to 0.35 %, respectively. The total amylose content ranged from 3.9 to 5.7 % of which 10.3 to 15.8 % were complexed by native lipid. The X-ray pattern was of the "A" type. The intensities of the major diffraction patterns followed the order: Mexican African A200D. The swelling factor followed the oder: A200 D African Mexican. All thre starches exhibited identical pasting temperatures. However, they differed with respect to the highest viscosity reached during the heating cycle (Mexican A200D African), viscosity at 95 degree C (Mexican A200D African), the extent of the breakdown (African A200D - Mexican) in viscosity (during the holding cycle at 95 degree C) and setback (A200D African Mexican). The gelatinization temperature ranges were 72.2 - 91.0 degree C (Mexican), 69.8 - 84.1 degree C (African) and 69.0 - 83.6 degree C (A200D). The enthalpy of gelatinization (J g(-1)) were 11.8 (Mexican), 12.3 (African) and 14.5 (A200D). The extent of acid hydrolysis (2.2 N HCl at 35 degree C) followed the oder: A200D African Mexican. The susceptibility of the starches towards hydrolysis by porcine pancreatic alpha-amylase followed the order: African A200D Mexican. The freeze-thaw stability followed the oder Mexican African A200D. The results of this study showed that bonding forces within the amorphous and crystalline regions are most pronounced in the Mexican cultivar.
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