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Research Project: Postharvest Quality and Processing of Sugarcane and Sweet Sorghum for Sugar and Ethanol Production

Location: Commodity Utilization Research

Title: Development of a research method to measure insoluble and soluble starch in sugarcane factory and refinery products

item Cole, Marsha
item Eggleston, Gillian
item Gilbert, Audrey
item Chung, Yoo Jin

Submitted to: Sugar Industry Technologists Meeting
Publication Type: Proceedings
Publication Acceptance Date: 8/28/2014
Publication Date: 10/1/2014
Citation: Cole, M.R., Eggleston, G., Gilbert, A., Chung, Y.J. 2014. Development of a research method to measure insoluble and soluble starch in sugarcane factory and refinery products. In: Proceedings of the 2014 Sugar Industry Technologists Meeting, Toronto, Canada. Vol. LXXIII:212-229.

Interpretive Summary: In sugarcane processing, starch is an impurity that negatively affects processing and reduces the quality of the sugar end-product. Existing industry methods used to measure starch in raw and refined sugars, measures mostly soluble starch with little impact in solubilizing insoluble starch. The purpose of this study was to develop a research method to measure total starch and determine the concentration of insoluble and soluble starch in various sugar products containing both high and low quantities of insoluble starch. The USDA research method uses a combination of microwaving and probe ultrasonication to rapidly and selectively solubilize starch with high precision and accuracy. This method also uses corn starch as a reference, incorporates a color blank, and removes unwanted particle contribution from sample results. To the best of our knowledge, this is the first report of the use of microwave-assisted probe ultrasonication to totally solubilize the insoluble starch content in any sugar product and allows for soluble and insoluble starch concentrations to be determined.

Technical Abstract: A rapid, quantitative research method using microwave-assisted probe ultrasonication was developed to facilitate the determination of total insoluble, and soluble starch in various sugar factory and refinery products. Several variables that affect starch solubilization were evaluated: 1) conductive boiling time, 2) microwave boiling time, 3) probe ultrasonication time, 4) water loss, 5) concentration, 6) sample color, and 7) sample. The optimized method solubilizes <40,000 ppm insoluble starch with microwave-assisted sonication in 6 min, has acceptable precision (<6% CV), accuracy (=95%), uses a corn starch reference, and incorporates a color blank to remove contribution from natural colorants found in industrial samples. This method was validated on factory and refinery samples, mixed juices (2% CV), massecuites (4%), molasses (7%), and raw sugars (12%); 100% satisfactory performance z-scores were also obtained. Total starch values obtained with this method were significantly higher than those measured with other methods commonly used by the sugar industry. The method also had the added benefit of allowing the determination of soluble and insoluble which is a great advantage to the sugar industry.