Submitted to: Journal of Food Composition and Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 15, 2005
Publication Date: June 2, 2006
Citation: Kim, S., Inglett, G.E. 2006. Molecular weight and ionic strength dependence of fluorescence intensity of the calcofluor/b-glucan complex in flow-injection analysis. Journal of Food Composition and Analysis. 19(5):466-472. Interpretive Summary: The American public is faced with an increased occurrence of obesity and the medical problems associated with it. A movement towards decreasing obesity has resulted in an effort to develop healthier foods. In recent studies, diets higher in soluble fiber exhibited a decrease in cholesterol levels and an improvement in glucose and insulin regulation. When developing healthier foods containing soluble fiber, it is important that its content be determined with an accurate method. This work describes a new method to accurately determine dietary fiber content in food products.
Technical Abstract: The flow-injection analysis (FIA) method has long been used for the quantitative determination of beta-glucans. FIA makes use of the enhanced fluorescence produced when beta-glucan forms complexes with Calcofluor. For successful application of this analysis method, the lowest molecular weight (MW) in the sample has to be higher than a critical MW below which the fluorescence intensity of the complex becomes weaker. Fluorescence measurements reveal that the fluorescence intensity of the Calcofluor/beta-glucan complex is strongly dependent on the ionic strength of the solution. At high ionic strength, fluorescence intensity is high and critical MW is low. At low ionic strength, on the other hand, fluorescence intensity is low and critical MW is high. Turbidity measurement shows that Calcofluor/beta-glucan complex forms aggregates in the solution and the rate of aggregate formation depends on the MW of beta-glucan and concentration of Calcofluor. This study indicates that the FIA method has to be used with solutions of high ionic strength and a high Calcofluor to beta-glucan ratio to broaden the applicable MW range of beta-glucan analysis.