Novel cold-brewed acidified beverages made from tannin-containing sorghum bran

Authors: Ardoin, Ryan; Smith, Brennan; Lea, Jeanne; Boue, Stephen; Smolensky, Dmitriy; SANTANA, ADINA - Kansas State University; Peterson, Jaymi

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: The bran layer of grains such as rice and sorghum are removed during milling, and usually go to low value production streams. Sumac sorghum bran contains valuable health-promoting compounds such as polyphenolics. Our research used this antioxidant-rich sumac sorghum bran to develop a model acidified bran beverage. The compounds were extracted by "cold-brewing" the bran in water, then filtering and adding other ingredients (citric acid, sugar, gum). Chemical analyses showed that the beverages contained many of the polyphenolic compounds present in the bran and demonstrated antioxidant capability. Sensory testing demonstrated that consumers were open to the novel concept of an antioxidant-grain-based beverage. The sweetened version, with lower bitterness intensity, was more acceptable than the unsweetened version. These results will be used to guide further research and development of acidified bran beverages using other grain sources (i.e., rice).

Technical Abstract: Introduction Sorghum bran, as milling byproduct, contains bioactive polyphenolic compounds. However, new food product development with sorghum bran is limited due to bitterness and astringency. Some consumers (supertasters) may be more sensitive to bitterness, and therefore avoid polyphenolic-containing foods. The present research developed a novel acidified beverage made from tannin-containing sumac sorghum bran. The objectives of this study were to characterize beverage phenolic profiles, measure in vitro antioxidant activity, and evaluate consumers’ perceptions of the beverage concept. Methods A sweetened (SB) and an unsweetened (UB) beverage were formulated and tested. Cold-brewing occurred at 3-4 ' for 24 hrs using 40 g sumac sorghum bran : 1 L water. Brews were acidified to pH 3.9 (citric acid), and held at 82 °C for 1 min. Other ingredients were minimal (sugar, gum) to focus on perceptions of basic tastes. Antioxidant profiles (HPLC), condensed tannins (vanillin-HCL), total phenolic content (TPC), oxygen radical absorbance capacity (ORAC), and 2-diphenyl-1-picrylhydrazyl (DPPH) assays were employed. Proximate analysis and color were measured. Consumers (N=114) evaluated beverages’ appearance, aroma, mouthfeel, and flavor (9-point hedonic scales); sweetness, sourness, and bitterness (JAR scales); and purchase intent (yes/no) before and after a sorghum-antioxidant message. Supertaster status was determined using an existing propylthiouracil and sodium chloride tasting method. Results Cold-water extraction (cold-brewing) of sorghum bran yielded beverages containing tannins (0.33 mg CE/mL) and other flavonoids (TPC = 0.53 GAE/mL) and displaying antioxidant capacity (3.96 mmol Trolox Equivalents/mL SB). Use of anionic kappa carrageenan kept proteins and associated polyphenolics suspended after acidification. Consumers’ supertaster status did not affect acceptability or perceived bitterness of beverages. SB was rated significantly (a=0.05) higher in mouthfeel (mean=6.2, 9-point hedonic scale) and flavor liking (mean=5.1), and lower in bitterness intensity (mean=1.8, 5-point intensity scale) than UB (mean=2.6). The sorghum/antioxidant information message significantly increased purchase intent of SB to 56%. Significance Novelty of cold-brewed acidified sorghum bran beverage was demonstrated in a US consumer population sample. The sweetened bran beverage (SB) was favored regardless of consumers’ sweet vs. unsweet tea preference, and sweetness suppressed bitterness. Using tannin-containing sumac sorghum bran, beverages with antioxidant capacity were developed, and acceptance was not associated with supertaster status.