Description and 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)-α-d-glucan and amylopectin, a branched d-glucan with mostly α-d-(1→4) and
approx 4% α-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 (α-amylase, β-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. β-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;
Mondamin.
Therapeutic Category
Antidote (iodine poisoning).
Therapeutic Category (Veterinary)
Internally: demulcent, mild astringent,
in diarrhea, as an antidote for iodine poisoning. Externally: absorbent,
emollient, in dusting powders and in ointments.