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Characterize acylated starch to determine applications.

Cassava (Manihot Esculenta Crantz) is one of the most widely grown tubers in the world and is a principal staple crop in Africa, Asia, Latin America and the Caribbean. Its root is rich in starch[??] about 20% to 30% on a wet basis. The extracted starch may be modified chemically.

The amylose and amylopectin ratio of starch governs its physical properties. This has been supported by experiments performed on Jamaican varieties of yam. Many think that the acylation of native starch from different cassava varieties will create unique functional properties of the modified starches produced, such as altered solubility, swelling power, viscosity and resistance to syneresis. These starches can then be classified and characterized to determine their industrial applications.

There is limited research on the starch structure of Jamaican cassava varieties. These could be potentially novel starches. The characterization of previously unknown starches would add to our knowledge of suitable starch sources. A better understanding of the behavior of these starches can lead to replacing corn starch as a major food source.

Jamaican scientists added acetic anhydride to starch in order to substitute the hydrogen of a hydroxyl group on the starch molecule with an acyl group. This was done by controlling the pH at 8.0 to 8.3 with the periodic addition of 0.1M of sodium hydroxide. The reaction was terminated by lowering the pH to 5.5 with the addition of 0.1M of hydrochloride.

The researchers determined the swelling power of the starch by preparing and weighing swollen starch granules. The solubility was determined by weighing the dried supernatant of the starch gels.

The researchers prepared a series of modified starches with a degree of substitution of 0.05, 0.1 and 0.2, as well as native starch. The degree of substitution is the average number of substituent groups attached per base or monomeric unit.

Starch with 0.2 degree of substitution demonstrated 1,100% swelling power and 0.38% solubility. Starch with 0.1 degree of substitution demonstrated 866% swelling power and 0.64% solubility. Starch with 0.05 degree of substitution demonstrated 670% swelling power and 1.79% solubility. Native starch demonstrated 306% swelling power and 2.34% solubility.

Further information. Ian Thompson, Department of Chemistry, The University of the West Indies, Mona, Kingston 7, Jamaica; phone: 876-977-1910; fax: 876-977-1835; email: ian.thompson02@uwimona.edu.jm.

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Author:Thompson, Ian
Publication:Emerging Food R&D Report
Date:Apr 1, 2019
Words:405
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