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United States Department of Agriculture

Agricultural Research Service

Research Project: Modification of Natural Polymers by Novel Processes

Location: Plant Polymer Research

Title: Preparation of starch-sodium lignosulfonate graft copolymers via laccase catalysis and characterization of antioxidant activity

Authors
item Shogren, Randal
item Biswas, Atanu

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 23, 2012
Publication Date: N/A

Interpretive Summary: This research found that corn starch having antioxidant properties could be made in a simple manner and that such a modified starch has potential use in food packaging, cosmetics, wound dressings, etc. Corn starches with new properties and applications could be created if techniques were developed to attach new types of molecules onto starch. In particular, it would be desirable to combine the good film forming properties of starch with the antioxidant/antimicrobial properties of plant polyphenolic compounds such as lignin or tannins. However, there have been no previous reports of such adducts since starch and polyphenols are not easily reactive with one another. It has now been shown that starch-lignin copolymers can be prepared using enzyme (laccase) catalysis in the presence of oxygen (air). This information will benefit scientists in academia and food/medical industries who are involved in making coatings for food preservation, increasing antioxidant levels in foods, improving air and UV stability of cosmetics and making antibacterial dressings.

Technical Abstract: Graft copolymers of waxy maize starch and sodium lignosulfonate (SLS) were prepared by T. Versicolor laccase catalysis in aqueous solution. Amount of SLS grafted based on phenol analysis was 0.5% and 1.0% in the absence and presence of 1-hydroxybenzotriazole (HBT), respectively. Starch-SLS graft copolymers were effective antioxidants as judged by DPPH radical scavenging activity. The presence of laccase caused a reduction in starch molecular weight although a cross-linked gel fraction was also observed when HBT was present. This new method for preparing starch chemically modified with phenolic compounds is simple and the resulting antioxidant polymers have potential in food, cosmetic and packaging applications.

Last Modified: 10/31/2014
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