Biochemical changes in phenols, flavonoids, tannins, vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.

Objective: To investigate the changes in total phenols, flavonoids, tannins, vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.

Methods: The changes in total phenols, total flavonoids, tannins, phenolic acids compounds, flavonoid components, vitamin E, β-carotene and antioxidant activity during soaking of sorghum grains were determined.

Results: Total phenols, total flavonoids, tannins, vitamin E, β-carotene and antioxidant activity in raw sorghum were ranged from 109.21 to 116.70, 45.91 to 54.69, 1.39 to 21.79 mg/100 g, 1.74 to 5.25, 0.54 to 1.19 mg/kg and 21.72% to 27.69% and 25.29% to 31.97%, respectively. The above measured compounds were significantly decreased after soaking. p-Hydroxybenzoic acid, vanillic acid, syringic acid and cinnamic acid represent the major phenolic acids in Dorado variety. While ferulic acid, p-coumaric acid, gallic acid and caffeic acid represent the major phenolic acids in Shandaweel-6. On the other hand, protocatechuic acid represents the major phenolic acids in Giza-15. Regarding flavonoids components, Dorado was the highest variety in kampferol and naringenin while Shandaweel-6 was the highest variety in luteolin, apigenin, hypersoid, quercetin and christen. Finally, Giza-15 was the highest variety in catechin. Phenolic acids, flavonoid compounds and antioxidant activities were decreased after soaking.

Conclusions: Sorghum varieties have moderate quantities from total phenols, total flavonoids, tannins, phenolic acids compounds, flavonoid components, vitamin E, β-carotene and antioxidant activity which decreased after soaking.