High-amylose corn starch

Although the term amylose dates to 1895, it was not until the 1940s that it became associated with the mainly linear chains of starch (see Chapter 3). Before this, little was known about the structure or identity of starch polymers. In 1946, R.L. Whistler, a carbohydrate chemist, and H.H. Kramer, a geneticist, set out to produce a com modification that would be the opposite of waxy corn, i.e. one in which the starch would be 

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Plantic Technologies Ltd is an Australian research company that offers products for thermoforming based on hydroxypropylated nongenetically modified high amylose corn starch. Its production capacity is of 7500 ton/year [134]. 

Figure 2.3 Photomicrographs of spherical (a,c,e) and toroid (b,d,l) spherulites obtained from slowly cooled, jet-cooked, high amylose corn starch, (a) and (b), phase contrast light micrographs, (c) and (d), polarized light micrographs showing birefringence, (e) and (f), scanning electron micrographs.

Landerito NA, Wang Y-J. 2005. Preparation and properties of starch phosphates using wrixy, common, and high-amylose corn starches. II. Reactive extmsion method. Cereal Chem 82 271-276. 

The relative content of amylose and amylopectin varies between species, and between different cultivars of the same species. For example, high-amylose pea starch comprises about 75% amylose whilst waxy corn starch contains more than 99% amylopectin. 

Xie, X., Liu, Q., Cui, S. W. (2006). Studies on the granular structure of resistant starches (type 4) from normal, high amylose and waxy corn starch citrates. Food Research International, 39, 332-341. 

Figure 6.1 Scanning electron micrographs of starches (a) normal maize (b) waxy maize (c) potato (d) wheat (e) sorghum (f) sweet corn (g) amaranth (h) high-amylose maize 7.10... 

Cationic starches are widely used as wet-end additives in the pulp and paper industry to enhance starch and filler retention during papermaking. Use of cationic starches increases paper strength and decreases biological oxygen demand (BOD) of paper mill effluent. Presently only cationic corn and potato starches are used by Canadian paper mills. The degree of substitution (DS) of normal, waxy, high-amylose barley... 

Starches with high amylose content, such as corn starch (28% amylose) retrograde more than starches with lower amylose content, such as potato starch (20% amylose). Redispersion of retrograded starch is energy-intensive due to extensive bonding. Temperatures of 115° to 120°C are required to solubilize amylose gels or crystals. Amylopectin gels can be redispersed at temperatures above 55°C. 

Cooking is traditionally done in kettles with acid-thinned corn starch chosen for its shorter texture and reduced hot viscosity, allowing more starch to be used for greater gel strength. With jet or tubular cookers, high-amylose starches are favored because... 

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