Waxy com starch

Figure 3. Viscosity of sodium and potassium salts of waxy com starch sulfate (DS 0.5)...

Waxy com starch, also known as waxy maize starch, consists of only amylopec-tin molecules, giving this starch different and useful properties (see Chapter 3). This genetic variety of com was discovered in China in the early 1900s, when com plants were transferred from the Americas. The starch stains red with iodine, not blue as ordinary starches do. When the com kernel is cut, the endosperm appears shiny and waxlike, and the com was termed waxy com or waxy maize. However, it contains no wax. 

Dextrinization of tapioca starch is well-known. The difficulty in dextrinizing corn starch,64 and the relative ease of tapioca starch conversion,65 have been described. The near-absence of lipids, which interfere with the dextrinization process, has given tapioca dextrins an advantage in stability and color because of their ease of manufacture and control. However, the economics of base starch supply have resulted in a significant shift to waxy com starch as a base for industrial dextrins, even though... 

Further improvements in the retention of pigment in the paper and enhanced sheet formation are obtained when amphoteric starches are used. Phosphate groups have to be added to cationic cornstarch to produce amphoteric properties. Cationic potato starch has a natural source of anionic charge due to its phosphate content. In recent years, waxy com starches, which consist entirely of amylopectin, have been modified for use as cationic or amphoteric agents for papermaking and surface sizing. 

Waxy com starch contains only amylopec-tin com starch contains both amylopectin and amylose. This results in a different viscosity profile (Figure 8-37). Com starch shows a lower peak viscosity and less breakdown during heating. After cooling, the viscosity continues to increase, probably because the amylose interlinks with the amylopectin. On further storage at 25°C, the slurry sets to a firm gel. Tapioca starch is intermediate between com and waxy com starch (Figure 8-37). This is explained by the... 

Achayuthakan, R, Suphantharika, M., and Rao, M. A. 2006. Yield stress components of waxy com starch-xanthan mixtures effect of xanthan concentration and different starches. Carbohydr. Polym. 65 469-478. 

In general, starch triacetates are soluble in acetic acid and, except perhaps for potato starch triacetate, are soluble in chloroform, 1,1,2-tri-chloroethane, tetrachloroethane, and other halogenated hydrocarbons. High grade starch triacetates do not appear to be soluble in ethyl acetate or alcohol, while some controversy exists as to the extent of their solubility in pyridine and acetone. Waxy com starch triacetate, perhaps due to its smaller molecular weight, is readily soluble in a wide variety of organic solvents. 

FIGURE 4.6 Heat capacity evolution of the crystallization of pregelatinized waxy com starch at 52°C. (From De Meuter, P., Rahier, H., and Van Mele, B., Ini. J. Pharm., 192, 77, 1999. With permission.)... 

Cassava starch Sweet potato starch Waxy com starch... 

In this work, the profile of CD production by the action of CGTase from Bacillus clausii strain El 6 in soluble starch and maltodextrin was studied. Furthermore, the action of this CGTase in the presence of other starch botanical sources such as cassava starch, sweet potato starch, com starch, and waxy com starch were analyzed. 

The CGTase action was evaluated on cassava starch, sweet potato starch, com starch, and waxy com starch. Substrates concentrations were at 2.5%. Enz5mie, conditions, and quantity were conducted as described above, except that aliquot samples were withdrawn periodically until 24 h. In an independent experiment, starches were gelatinized by autoclave process. The percentage of starch converted into CDs was calculated by ratio of total grams of CDs formed divided per gram of starch and multiplied per 100. 

Soluble starch was a better substrate than maltodextrin for CD production, so other substrates were also used for CD production. The content and structural characteristics of amylose and amylopectin present in starches may vary depending of their botanical sources. So, it was interesting to investigate this parameter regarding to CD formation under CGTase action. Cassava starch, sweet potato starch, com starch and waxy com starch were used. 

Generally, starches contain about 20 to 30% of amylose and 70 to 80% of amylopectin, and these concentrations change with the botanical source of starch. Cassava starch, sweet potato starch, com starch, and waxy com starch showed, respectively, 17.0, 20.7, 25, and less than 1% of amylose (28,29, 30). The ratio amylose/amylopectin is an important factor to consider for CD production. The helicoidal stracture of amylose with loops of six to seven glucose imits can contribute with action of CGTase on a- and 3-CD formation (2). 

Starch acetates with a DS at or below 0.2 are visibly indiscernible from nonderivatized starches. At a pH of 11, a low DS starch acetate will deacetylate at room temperature in as little as four hours. Chemically, the difference is significant. Waxy com starch with a gelatinization temperature of 1°C will display a 64°C gelatinization temperature with as low as a 1.8% acetyl content. This has been demonstrated with a variety of starches (42). When cooled, the viscosity of low DS starch acetates increases more slowly than nonderivatized starches. Low DS starch acetates are... 

Extrusion effects on starch are significant since starchy cereals and tubers provide the bulk of calories consumed by most people, particularly those living in less-developed nations. Gelatinization occurs at lower moisture levels (12—22%) than is possible with other food processing methods. Qu and Wang (1994) hypothesized that waxy com starch extrusion is dominated by melting, which follows a zero order kinetics, rather than gelatinization, a first order reaction. 

Potato starch shows a very high maximum ( 4000 Brabender units), followed by a steep drop. Waxy com starch exhibits similar behavior, except that the maximum is not as high. In normal com starch, the maximum is still lower, but the following drop is slight, i. e., the granules are more stable. Under these conditions, amylomaize starch does not swell, even though ca. 35% of... 

Most of the starch used in adhesives in the United States is produced from com or maize. There are four commercially available starch types that are used in adhesives. These are waxy com starch, regular com starch, high amylose type V com starch, and high amylose type VII corn starch. The major difference between these starches is in the amount of amylose contained in them—approximately 0, 28, 55, and 70%, respectively, by iodine titration. Other starches usable in adhesives include sorghum... 

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