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Acid degradation of starch. The effect of acid and starch type.

Singh, V. and Ali, S. Z. (2000) Acid degradation of starch. The effect of acid and starch type. Carbohydrate Polymers, 41 (2). 191-195, 14 ref..

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Starch from cereals (wheat, maize and finger millet) pulses (chick pea and green gram), tuber (potato) and root (tapioca) was modified with different acids (0.5 N, 1.5 h, 50°C). Molecular weight (number average, ) of these starches decreased after modification, H3PO4 causing the least and HCl and HNO3 the highest reduction. Gel permeation chromatography of native starches using Sepharose CL 4B gave mainly two fractions. Fraction I (Fr. I), a higher molecular weight component eluting in the void volume and Fraction II (Fr. II), a lower molecular weight component that entered the gel and eluted at higher elution volumes. After acid modification, the carbohydrate content of Fr. II increased while that of Fr. I decreased. The magnitude of the effect for different acids followed the same pattern as was the case for molecular weight. Very high increase in the total carbohydrate content in Fr. II was seen in cereal starches followed by pulses, root and least by tuber. The λmax values of the peak of Fr. I increased in cereal and millet starches after modification by 9 to 14 nm, but either remained the same or decreased to some extent in other starches. The peak of Fr. II of modified starches had similar Kav to that of the respective native starch suggesting that the degraded portion had a molecular size similar to that of Fr. II of the native starch. However, the λmax of the peak of Fr. II decreased after modification indicating that degraded portion of Fr. I which entered the gel and eluted with the peak of Fr. II was branched.

Item Type: Article
Uncontrolled Keywords: Starch; Gel permeation chromatography; Acid modification
Subjects: 600 Technology > 08 Food technology > 25 Sugar/Starch/Confectionery
Divisions: Grain Science and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 19 Jul 2011 05:27
Last Modified: 19 Jul 2011 05:27
URI: http://ir.cftri.com/id/eprint/2641

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