Evaluation of polyphenols content and antioxidant ability of commercial herbal beer

Herbs are rich in polyphenols compounds that are often added to beer to boost its antioxidant ability. To prove herbs can efficiently enhance the antioxidant ability of beer, the total polyphenols and flavonoids content, the distribution of phenolics profile, and antioxidant ability in commercial herbal beers were analyzed in this work. The results showed that most herbal beers had stronger antioxidant ability than conventional beers. The total polyphenols content in most herbal beers (250.8–1063.5 mg/L) was higher than that in conventional beers (179.2–308.4 mg/L), especially free phenolic acids (3.151–26.469 mg/L) such as gallic acid (0.248–2.853 mg/L), chlorogenic acid (0.422–6.420 mg/L), vanillic acid (0.567–10.256 mg/L), and caffeic acid (0.422–10.093 mg/L), which can explain the strong antioxidant ability of herbal beers to a certain extent. Among them, roselle beer (ROL) and jasmine beer (JAS) performed the strongest antioxidant ability. Furthermore, according to the distribution of phenolics profile, it was found that ROL and JAS had highest content of flavonoids including catechol, epicatechin, and quercetin compared with all beers. This was an important reason why ROL and JAS had the strongest antioxidant ability. In a word, the addition of herbs in beer brewing can effectively improve the content of polyphenols and antioxidant ability of beer, especially the herbs rich in flavonoids have the most significant contribution to the antioxidant ability of beer, which is helpful to improve beer quality.