Author
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Rendleman Jr, Jacob |
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Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/8/2002 Publication Date: N/A Citation: N/A Interpretive Summary: New and expanded markets are needed to utilize starch, particularly corn starch, which is produced in large quantity in the U.S. Amylose, a starch form obtainable from ordinary corn starch, not only has potential use as a "low-calorie," essentially non-digestible component of foods, it also has potential use as an encapsulating agent that permits controlled release of substances bound by the amylose. In the work reported herein, studies were made of the encapsulation of iodine by amylose under different reaction conditions in order to determine the effect of those conditions on product composition. Certain of the amylose-iodine products, because of their unique composition and their ability to release iodine slowly, might be useful to physicians in the treatment of injuries. These investigations will provide scientists with information about starch behavior that will assist them in their efforts to find new uses for renewable resources such as corn. Those efforts will ultimately lead to the development of products that will create greater demand for corn products in the marketplace. Technical Abstract: The molecular-iodine and iodide-ion contents of starch-iodine complexes, prepared by subjecting corn amylose (average degree of polymerization, dp, 1050), low-molecular-weight amylose (dp 6l-69), amylose-cyclohexanol complexes, and native corn starches to iodine vapor for 30 days under different conditions of relative humidity (RH), were determined by titrations with KIO3 and Na2S2O3. Iodide content generally increased with increase in relative humidity. A hybrid corn starch of 64% amylose content yielded, at l00% RH, a complex containing 10.0 wt% of total iodine (I/I**- = 3.7). Low-dp amylose, waxy maize starch, and ordinary corn starch exhibited low reactivity toward iodine vapor, even at 100% RH; however, a cyclohexanol complex of low-dp amylose reacted at 100% RH, with elimination of cyclohexanol, to produce a starch-iodine complex of unusually high iodine content (33.l wt% of total iodine; I/I**- = 3.65). The behavior of corn amylose toward iodine was found to be dependent upon its method of preparation from corn starch. One method yielded an amylose that was very resistant to iodine at 0% RH, but which was very reactive at 30-100% RH, producing a complex that contained as much as l8.5 wt% of total iodine (I/I**- = 3.49). A different procedure for preparing amylose gave a starch that, at 0% RH, formed a complex containing 2l.8 wt% of molecular iodine and no detectable amount of iodide ion. A cyclohexanol complex of corn amylose reacted with iodine at 100% RH, with elimination of cyclohexanol, to form an iodine complex having a total iodine content of 3l.6 wt% (I/I**- = 3.91). For most of the iodine complexes there was a close similarity between I**- content and H**+ content. |
