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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPING BIOCONVERSION PROCESSES FOR HIGH-VALUE CARBOHYDRATE PRODUCTS Title: Optimization of Process Conditions for Enzymatic Modification of Alternan using Dextranase from Chaetomium erraticum

Authors
item Leathers, Timothy
item Nunnally, Melinda
item Cote, Gregory

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 17, 2010
Publication Date: May 18, 2010
Citation: Leathers, T.D., Nunnally, M.S., Cote, G.L. 2010. Optimization of process conditions for enzymatic modification of alternan using dextranase from Chaetomium erraticum. Carbohydrate Polymers. 81(3):732-736.

Interpretive Summary: This research determined the optimal conditions for production of a modified microbial gum that resembles gum arabic. A domestic replacement for gum arabic would be highly beneficial to the food industry, as it is exclusively imported and varies in price, quality, and availability. Using a commercially available food-grade enzyme, process conditions were optimized for modification of a microbial gum such that it more closely resembles gum arabic. These results are important to researchers and the food industry because this method conveniently provides sufficient quantities of material for applications testing.

Technical Abstract: Alternan is a unique branched glucan with alternating a-(1 ' 6) and a-(1 ' 3) backbone linkages. We previously described the modification of alternan to a reduced molecular weight form using dextranase from Penicillium sp. The solution viscosity properties of this modified alternan resemble those of commercial gum arabic. In this study we optimize process conditions for modification of alternan using commercial dextranase from Chaetomium erraticum. This enzyme is considered GRAS and thus suitable for potential food applications. Optimal conditions were 10% alternan, pH 4.5, 50°C, and 125 IU dextranase/ml (assayed at 28°C, pH 5.0). Using these conditions, we scaled up production of modified alternan, permitting for the first time the isolation of separate peaks of modified alternan. Methylation analysis revealed a progressive loss of linear 1,6 linkages during modification. Optimized conditions will be useful to produce modified alternan for applications testing.

Last Modified: 10/31/2014
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