Comparison of Three Methods to Isolate Starch From Waxy Sorghum Grains

ABSTRACT Background and Objectives Waxy sorghum contains essentially only amylopectin in its endosperm starch and has unique properties that could be potentially used in value‐added food ingredients as an effective thickener. The objectives of this study were to develop an efficient process for isolating starch from waxy sorghum grains using alkaline protease and to compare the properties of starches isolated by enzymatic methods with that of starches isolated by the traditional wet milling method. Two starch isolation methods based on protease treatment were developed using whole and decorticated waxy sorghum grains. Those two methods were compared with a traditional wet milling method to evaluate the efficiency of the isolation process and properties of the starches isolated, including starch recovery, yield, residual protein, ash content, damaged starch content, color, as well as pasting and thermal properties. Findings Starch recovery showed no statistical differences among the three methods, and all isolated starches exhibited desired purity regardless of the method employed. However, enzymatic treatment methods not only produced starches with lower residual protein (0.18%–0.22%) but also resulted in significantly greater peak (1992–2023 cP), breakdown (1123–1172 cP), and setback viscosities (275–355 cP) compared with the waxy sorghum starch isolated by the wet milling. The starches isolated by wet milling and enzymatic treatment of decorticated sorghum exhibited similar onset and peak gelatinization temperatures, while both methods produced starches with better color quality (higher L *, lower b *) compared to starches isolated from whole sorghum using the enzymatic treatment. Conclusion Enzymatic treatment of decorticated sorghum could be used as an effective method for starch isolation at the laboratory scale, with promising potential for application in industrial‐scale processes. Significance and Novelty An efficient process was developed for isolating waxy sorghum starch, providing a sustainable alternative to wet milling by balancing processing efficiency and starch quality while maintaining high starch recovery.