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A rapid research method using microwave-assisted probe ultrasonication was developed to quantify total, insoluble, and soluble starch in various sugar crop products. Several variables affecting starch solubilisation were evaluated, (1) heating method, (2) boiling time, (3) probe ultrasonication time, (4) water loss, (5) concentration, (6) sample colour, and (7) sample. The optimised method solubilises < 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 colour blank to remove contribution from natural colourants found in industrial samples. This method was validated using factory samples and found applicable to sugarcane and sweet sorghum bagasse (3% CV), mixed juices (2%), 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 using other methods presently accepted by the sugar industry., (Published by Elsevier Ltd.)

In sugarcane processing, starch is considered an impurity that negatively affects processing and reduces the quality of the sugar end-product. In the last decade, there has been a general world-wide increase in starch concentrations in sugarcane. Industrial α-amylases have been used for many years to mitigate issues arising from starch in the sugarcane industry. Mixed results have prompted further studies of the behaviour of different physical forms of starch and their interactions with α-amylases during processing. By using corn starch as a reference in model juices and syrups, processing parameters, activities, and hydrolysis of insoluble, swollen, and soluble starch forms were evaluated for two commercial α-amylases with high (HT) and intermediate (IT) temperature stability, respectively. The ability of starch to solubilise across a sugarcane factory is largely limited by increased Brix values. Optimum target locations and conditions for the application of α-amylases in sugarcane processing are discussed in detail., (Published by Elsevier Ltd.)