Title: Starch
Additional Names: Amylum
Literature References: (C6H10O5)n. Carbohydrate polymer stored by plants; analogous to storage of fats by animals. Occurs as discrete granules in the mature grain of corn, Zea mays Linné, Gramineae or of wheat, Triticum aestivum Linné, Gramineae or tubers of potato, Solanum tuberosum Linné, Solanaceae or rice, Oryza sativa Linné, Gramineae. Starches are mixtures of two polymers: amylose, a linear (1®4)-a-D-glucan and amylopectin, a branched D-glucan with mostly a-D-(1®4) and approx 4% a-D-(1®6) linkages. The starch in corn contains approx 27% amylose and 73% amylopectin, with these two polymers so associated in the crystal lattice that they are practically insol in cold water or alcohol. Refs: J. N. BeMiller, "Starch Amylose" in Industrial Gums, R. L. Whistler, Ed. (Academic Press, New York, 2nd ed., 1973) pp 545-566; E. L. Powell, "Starch Amylopectin", ibid., pp 567-576.
Properties: Although hydrolysis will not take place in cold water, and starch is comparatively resistant to naturally occurring enzymes, the reaction may be brought about by the use of acids or enzymes (a-amylase, b-amylase, amyloglucosidase). The hydrolysis reaction follows a different path depending on whether acids or enzymes are used. While acid hydrolysis produces a mixture of saccharides, the enzymes give more specific products. b-Amylase, for example, breaks off mostly maltose units, and amyloglucosidase yields mainly D-glucose. Chemistry and technology: R. L. Whistler, E. F. Paschall, Eds., Starch: Chemistry and Technology 2 vols. (Academic Press, New York, 1965); J. A. Radley, Ed., Starch and Its Derivatives (Chapman & Hall, London, 4th ed., 1968). Comprehensive description: A. W. Newman et al., Anal. Profiles Drug Subs. Excip. 24, 523-577 (1996).
CAUTION: Potential symptoms of overexposure are irritation of eyes, skin, mucous membranes; cough, chest pains; dermatitis; rhinorrhea. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 284.
Use: Starching and sizing fabrics, etc.; paste; as indicator in iodometric analyses. In the food industry. Pharmaceutic aid (tablet disintegrant, filler, binder); dusting powder. Dietetic grades of corn starch are marketed as Maizena (CPC) ; Mondamin (CPC) .
Therap-Cat: Antidote (iodine poisoning).
Therap-Cat-Vet: Internally: demulcent, mild astringent, in diarrhea, as an antidote for iodine poisoning. Externally: absorbent, emollient, in dusting powders and in ointments. |