Comparison of Three Methods to Isolate Starch From Waxy Sorghum Grains

Authors: HUANG, YING - Kansas State University; Wu, Xiaorong; Bean, Scott; SHI, YONG-CHENG - Kansas State University

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2025
Publication Date: 10/16/2025
Citation: Huang, Y., Wu, X., Bean, S.R., Shi, Y. 2025. Comparison of Three Methods to Isolate Starch From Waxy Sorghum Grains. Journal of Cereal Science. Volume 102, Issue 6 Nov 2025 Pages909-1087. https://doi.org/10.1002/cche.70017.
DOI: https://doi.org/10.1002/cche.70017

Interpretive Summary: Waxy sorghum starch has special functional properties that could be potentially used as value-added food ingredients. The objectives of this study were to develop an efficient process to isolate starch from waxy sorghum and to compare the properties of waxy sorghum starches isolated using different processes. Three methods were used in this study: Conventional wet milling of whole waxy sorghum; protease treatment of whole waxy sorghum; and and protease treatment of decorticated waxy sorghum. Parameters such as starch recovery, yield, residual protein, ash, damaged starch, color, pasting and thermal properties of the isolated starches were evaluated and compared. No significant difference was observed in starch recoveries among the three methods. All isolated starches exhibited desired purity. The starches isolated with enzymatic treatment had lower residual protein contents and higher viscosities than the waxy sorghum starch isolated by the conventional wet milling method. No difference was found in the thermal properties among the isolated waxy sorghum starches. The starches produced using enzymatic treatment had better color quality. Overall, the enzymatic treatment of decorticated sorghum was an effective method for producing quality waxy sorghum starch.

Technical Abstract: Waxy sorghum contains essentially only amylopectin in its endosperm starch and has special 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 to isolate waxy sorghum starch and compare the properties of the waxy sorghum starches isolated by enzymatic processes and traditional wet milling process. Alkaline protease was utilized to isolate starch from both decorticated and whole waxy sorghum grain, providing a comparative analysis against the conventional wet milling. To evaluate the efficiency and effectiveness of the isolation process, key parameters such as starch recovery, yield, residual protein, ash, damaged starch, color, as well as pasting and thermal properties were determined. Starch recovery showed no statistically significant 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. As a result, 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.