Optimization of tannin-containing sorghum bran addition to gluten-free bread

Authors: Ardoin, Ryan; Smith, Brennan; Bean, Scott; Aramouni, Fadi

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2023
Publication Date: 1/30/2023
Citation: Ardoin, R., Smith, B., Bean, S., Aramouni, F. 2023. Optimization of tannin containing sorghum bran addition to gluten-free bread. Journal of Food Science. 88(3):952-961. https://doi.org/10.1111/1750-3841.16477.
DOI: https://doi.org/10.1111/1750-3841.16477

Interpretive Summary: People with Celiac disease cannot eat wheat products because of the damage that the protein gluten does to their bodies. These and other consumers choose to purchase gluten-free baked goods, which are often less nutritious. Gluten-free grains like sorghum and rice contain valuable nutrients in their bran which often goes to waste. Our research optimized the use of sorghum bran (containing dietary fiber and antioxidants) in gluten-free bread using a technique called response surface methodology. Bread containing 14% sorghum bran was "high in fiber" with over five times the antioxidant capacity of a control recipe. One hundred consumers rated the quality of the gluten-free bran bread favorably compared to the control bread. Rice bran also contains antioxidants which may reduce the risk of disease and is free from gluten. In the current study, sorghum bran improved the nutritional quality of gluten-free bread without compromising acceptability. In future studies, the same optimization techniques can be used with other bran sources, such as rice, to provide gluten-free consumers with healthier options.

Technical Abstract: To achieve sensory quality reminiscent of wheat-containing products, gluten free (GF) breads often lack in nutrients. This presents nutritional challenges for celiac-positive individuals and fails to meet expectations of healthfulness for non-celiac GF consumers. Sorghum (Sorghum Bicolor) flour can be used produce acceptable GF breads, and tannin-containing varieties contain antioxidants concentrated in the bran along with dietary fiber. Using a central composite design, tannin-containing sumac sorghum bran, gum (xanthan + guar), and water levels were optimized in a GF sorghum-based bread formulation. Loaf specific volume and gas cells/cm2 were maximized while minimizing hardness and cell wall thickness. The optimum formulation containing 14.2% sorghum bran, 1% gum, and 145% water (flour basis) effectively increased dietary fiber in bread to 13.4% (considered “high fiber”) and showed oxygen radical absorbance capacity of 61.6 µmol TE/g. This optimum formulation did not differ from a sorghum flour-based control bread in consumers’ (N=100) liking of color, texture, flavor, overall acceptability, nor willingness to buy (WTB). All mean hedonic scores (numbered 9-point scale) were above 5, while average WTB was 4.7 for the optimum formulation and 4.6 for the control (9-point Likert scale) among consumers varying in GF bread consumption habits. Perceived bread bitterness was low (averaging 2.85 on 9-point intensity scale), did not vary between samples despite marked differences in antioxidant capacity, and was not correlated with WTB. When utilizing effective optimization models with key functional ingredients, sumac sorghum bran addition can enhance dietary fiber and antioxidant potential in sorghum-based GF breads without compromising quality attributes.