Physicochemical Characteristics of Yam Starches

Abstract

Starch from tubers of Dioscorea alata, Dioscorea cayenensis, Dioscorea dumetorum, and Dioscorea rotundata was isolated and some of the important characteristics determined. Amylose and amylopectin fractions were obtained by aqueous leaching technique. All the starches appeared to have definite but minor differences in iodine binding capacity, swelling power, solubility, intrinsic viscosity, and amylose/amylopectin ratio. Brabender amylogram of each starch showed no distinct peak viscosity, and the general amylograph pattern was distinctly different from typical amylographs of cereal starches. Amylose fractions from each starch variety exhibited variable degree of fl-amylolysis limits ranging from 92-97.5%, and an average molecular weight for amylose triacetate of 210,000 to 265,000. Amylopectin fractions subjected to debranching by pullulanase gave essentially two chain populations of polysaccharides with degree of polymerization of approximately 13-27 and 47-65, respectively. Average unit chain length of the amylopectins ranged from 19 in Dioscorea rotundata to 24 in Dioscorea dumetorum.

The effect of hydroxypropylation on the structure and physicochemical properties of native, defatted and heat-moisture treated potato starches

“…The internal lipids of cereal starches are predominantly monoacyf lipids, with the major component being Iysophospholipids (of which Iysophosphatidylcholine is the major component) and free fatty acids (Hargin & Morrison, 1980;Morrison, 1981 (Morrison, 1981), whereas prolonged extraction with hot aqueous alcoholic solvent systems (Morrison, 1981) or disruption of the granularslructure by acid hydrolysis (Goshimaetat., 1985)isrequiredfortheefficientremoval6f bound lipids. The amount of total starch lipids (surface and bound) has been found to be in the range of 0.7-1.2% in cereals (Morrison & Milligan, 1982;Vasanthan & Hoover, 1992b;Takahashi & Seib, (1988), 0.01-0.87% in legumes (Hoover & Sosulski, 1985), and 0.08-0.19% in tubers and roots (Vasanthan & Hoover, 1992b;Emiola & Delarosa, 1981;Goshima etat., 1985). Zobel (1988a) suggested that lipids in starches may be responsible for effecting an amylose separation within the granule.…”

Relationship between ?-amylase degradation and the structure and physicochemical properties of legume starches

“…The internal lipids mostly are monoacylglycerides, with the major components being lysophospholipids and free fatty acids (Hargin and Morrison, 1980;Morrison, 1981;Vasanthan and Hoover, 1992). Total starch lipids (surface plus internal) have been found to be generally in the range of0.7-1.2% in cereals (Morrison and Milligan, 1982;Takahashi and Seib, 1988;Vasanthan and Hoover, 1992), 0.01-0.87% in legumes (Table 2-3) and 0.08-0.19% in tubers and roots (Emiola and Delarosa, 1981;Goshima et al, 1985;Vasanthan and Hoover, 1992).…”

Potentials of tropical starches as pharmaceutical excipients: A review

“…The variation in their physicochemical properties as well as the morphological difference in size and shape of starch granules ( Fig. 1) has been attributed to the difference in the botanical sources as well as the biosynthesis of the starch granules and the physiology of the plant [6][7][8][9][10]. Dioscorea starch granules have been shown to vary in shape from spherical, oval to polygonal shape depending on the species with granule size ranging from 2 to 50 mm [11].…”

“…When converted into pastes and used as a binding agent in tablet formulation, sweet potato starch paste was found to produce tablets with higher bond strength than corn starch [38] indicating its potential usefulness as alternative binding agent to produce tablets with particular tableting and mechanical properties. [6]; (c) D. dumetorum [6]; (d) D. alata [6]; (e) D. esculenta [7]; (f) D. cayenensis [9]; (g) D. nipponica [10]; (h) D. bulbifera [10]; (i) D. septemloba [10].…”

“…The physicochemical and material propertes of yam starches have been shown to vary depending on the Dioscorea species [1,[6][7][8][9][10]. The variation in their physicochemical properties as well as the morphological difference in size and shape of starch granules ( Fig.…”