Effects of Green Tea Substituting Hops on Beer Fermentation Process, as well as Physicochemical Properties, Antioxidant Activity, Aroma Components of Beer

The development of tea beer has become a current research hotspot in the brewing industry. In this study, following standard beer production procedures, varying amounts of green tea were added during wort boiling to replace hops. The aim was to eliminate hop-related interference, investigate how adding tea affected the fermentation process, and assess the feasibility of using tea as a substitute for hops in beer brewing. The effects of green tea addition on physicochemical properties, volatile compounds, and sensory characteristics were compared both during fermentation and after fermentation was completed. The results indicated that a tea addition level of 8 g/L was the most suitable for brewing tea beer. Tea addition increased the total phenolic content in wort (182-415 mg/L), enhanced the yeast growth rate and maximum cell density, and improved both alcohol content (3.71-4.82%) and real degree of fermentation (54.79-68.42%). Antioxidant indices were also markedly improved, including DPPH radical scavenging capacity (2.58-4.12 mmol/L), ABTS radical scavenging capacity (2.80–18.28 mmol/L), and total reducing power (2.55-3.47 mmol/L). Volatile compounds in tea beer were further analyzed by HS-SPME-GC-MS, showing that tea addition increased the levels of common aroma-active compounds (ethyl acetate, ethyl hexanoate, and ethyl heptanoate), resulting in a richer aroma profile. In addition, several characteristic aroma compounds were identified (heptyl acetate, ethyl benzoate, and ethyl phenylacetate). Overall, these findings could serve as a reference for industrial production of tea beer and the development of novel beer products.