Consumer perceptions and antioxidant profiling of acidified cold-brewed sorghum bran beverages

Abstract

Sumac sorghum (Sorghum bicolor L. Moench) bran contains polyphenolic compounds with health-promoting properties. Functional food product development can add economic value to sorghum bran, but acceptability may be limited by bitter taste. An acidified cold-brewed sorghum bran beverage was developed, and simplified sweetened (SB) and unsweetened (UB) versions were analyzed for antioxidant profiles (total phenolic content, phenolic profiling via HPLC, condensed tannins, oxygen radical absorbance capacity, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging) and sensory properties. Beverages contained condensed tannins (average of 0.33 mg catechin equivalents per milliliter) along with other flavonoids and demonstrated in vitro antioxidant capacity (3.32-3.96 mmol Trolox equivalents per milliliter). One hundred fourteen consumers, grouped by 6-n-propylthiouracil (bitterness) taster status, rated acceptability (9-point hedonic scales), bitterness intensity (5-point scale), and purchase intent (PI; yes/no) of model beverages. Although the concept was novel, SB was clearly more acceptable to consumers regardless of preference for sweet versus unsweet tea (as a reference product concept). Mean mouthfeel and flavor liking scores were significantly higher for SB (6.2 and 5.1, respectively) than UB (4.8 and 3.0, respectively). Bitterness was suppressed by the sweetness in SB (mean bitterness intensity of 1.8 vs. 2.6 for UB), although 21% of consumers still found it "too bitter." However, consumers' taster status did not affect beverage acceptability nor bitterness perceptions at present phenolic levels (0.53 gallic acid equivalents per milligram). After a sorghum/antioxidant information message, positive PI increased to 56% for SB, impacting more females than males. Enhanced familiarity and effective product messaging can improve acceptability of acidified cold-brewed sorghum bran beverages as a novel functional food product concept. PRACTICAL APPLICATION: New food applications of cereal bran can provide value in terms of byproduct utilization and delivery of health-promoting ingredients. Sorghum bran beverages demonstrated antioxidant activity, and the sweetened formulation showed decreased bitterness and increased acceptability. Consumers were positively influenced by antioxidant information, although most had not previously consumed sorghum.

Keywords: beverage; cold-brewing; sorghum bran; supertaster; tannins.