Changes in phenolics, γ-aminobutyric acid content and antioxidant, antihypertensive and hypoglycaemic properties during ale white sorghum (Sorghum bicolor (L.) Moench) brewing process

Abstract

Effects of white sorghum brewing process on free amino-acids, γ-aminobutyric acid (GABA), phenolics and bioactivity, including antioxidant (by ABTS+ and reducing power, RP, methods), antihypertensive (angiotensin converting enzyme-I, ACE-I inhibition assay), and hypoglycaemic activity (α-glucosidase inhibition assay) were evaluated. Brewing process decreased free amino acids, increased significantly GABA and phenolic contents, and modified positively the bioactive potential. ABTS and α-glucosidase inhibition activity correlated positively with at least one of the phenolic acids evaluated. Ale white sorghum beer presented high content of GABA (7.8 mg/L), phenolics (40.7 mg total phenolic acids/L), antioxidant activity (9.14 mmol Trolox equivalent/L, and 48.8 mmol ascorbic acid equivalent/L, for ABTS+ and RP, respectively), and exhibit ACE-I inhibition (1.0 µg captopril equivalent/L) and α-glucosidase inhibition (34.5 mg acarbose equivalent/L) activities. The level of bioactive compounds and its low ethanol content (2.3%), make beer obtained from malted white sorghum a potential functional beverage.