Effect of flour particle size on the glycemic index of muffins made from whole sorghum and comparison to muffins made from whole corn, brown rice, whole wheat, or refined wheat flours

Authors: PRUETT, ASHLEY - Kansas State University; Aramouni, Fadi; Bean, Scott; HAUB, MARK - Kansas State University

Submitted to: Foods
Publication Type: Review Article
Publication Acceptance Date: 11/14/2023
Publication Date: 11/21/2023
Citation: Pruett, A., Aramouni, F.M., Bean, S.R., Haub, M. 2023. Effect of flour particle size on the glycemic index of muffins made from whole sorghum and comparison to muffins made from whole corn, brown rice, whole wheat, or refined wheat flours. Foods. https://doi.org/10.3390/foods12234188
DOI: https://doi.org/10.3390/foods12234188

Interpretive Summary: Consumption of whole grain foods provides many human health benefits and may help control blood sugar and insulin responses to meals. Likewise, the unique properties of sorghum flour are increasingly being studied for potential health benefits with one area of emphasis on the impact of sorghum consumption on preventing and mitigating type 2 diabetes. Thus, the objective of this research was to determine the glycemic index of muffins made from whole grain sorghum flour ground to three different particle sizes (fine, intermediate, coarse) and to compare the glycemic index to whole grain corn, wheat, and rice flours produced using the same product formula. Flour particle size influenced the glycemic index of sorghum-based muffins, with the lowest glycemic index found when using sorghum flour with an intermediate particle size. Among the samples tested in this project, muffins made using sorghum flour with an intermediate particle size and those made from brown rice had the lowest glycemic index. These results can assist in the product development process to advance the quality of healthy, gluten free sorghum-based foods for consumers.

Technical Abstract: The unique properties of sorghum are increasingly being studied for potential health benefits with one area of emphasis being the impact of sorghum consumption on preventing and mitigating type 2 diabetes. The glycemic index (GI) of muffins made from whole grain sorghum flour ground to three different particle sizes (fine, intermediate, coarse) was tested on 8 healthy volunteers (ages 18-40) and compared to the glycemic index of whole grain corn, wheat, and rice flours produced using a similar product formula. Sorghum flour ground through a 0.5mm screen (“fine”) had overall similar particle size to the brown rice flour ground using a 0.5mm screen. The range of GI values was 32 to 56, with only the GI of intermediate milled sorghum flour being smaller than that of corn, rice and wheat (p<0.05).The lowest glycemic index (32 +/- 17) was found when using sorghum flour with an intermediate particle size (167+/- 4µm). Muffins made using brown rice had the next lowest glycemic index. at 37 +/- 17. All GI values calculated had large standard deviation which is common for these type of studies. These results can assist in the product development process to advance the quality of healthy, gluten free sorghum-based foods for consumers. Keywords: sorghum; glycemic index; flour particle size; wheat; corn; whole grain; rice