Green tea has great potential to enhance the quality of beer. In this study, green tea was added at different stages of beer brewing, and evaluated the antioxidant capacity, volatile components, as well as sensory quality. The results showed that the addition of green tea during the start of boiling has great potential for application, and the green tea beer (GTB) had remarkable antioxidant properties (ABTS radical scavenging ability, 8.67 mmol TE/L; DPPH radical scavenging ability, 3.97 mmol TE/L; reducing power, 3.28 mmol TE/L), and an excellent sensory quality (acceptance, 6.09/9). HPLC analysis indicated that the principal phenolics in GTB were catechin and caffeic acid, in addition, the relative amounts of ferulic acid, gallic acid can be used to differentiate between GTB and beer. HS-SPME-GC-MS analyses showed that ethyl caprylate, ethyl nonanoate, ethyl caprate, linalool, and phenethyl alcohol were potentially significant for the aroma profile of GTB.

Craft beer brewers need to learn process control strategies from traditional industrial production to ensure the consistent quality of the finished product. In this study, FT-IR combined with deep learning was used for the first time to model and analyze the Plato degree and total flavonoid content of Qingke beer during the mashing and boiling stages and to compare the effectiveness with traditional chemometrics methods. Two deep learning neural networks were designed, the effect of variable input methods on the effectiveness of the models was discussed. The experimental results showed that the CARS-LSTM model had the best predictive performance, not only as the best quantitative model for Plato in the mashing (R²p = 0.9368) and boiling (R²p = 0.9398) phases but also as the best model for TFC in the boiling phase (R²p = 0.9154). This study demonstrates the great potential of deep learning and provides a new approach to quality control analysis in beer brewing.

Crushing and enzyme treatment are pivotal factors that cannot be ignored in the mashing stage of qingke (hull-less barley) craft beer brewing. This study aimed to explore the impact of different mashing conditions on physicochemical, fermentation, and antioxidant properties of qingke wort as well as elucidate the mechanisms of mashing conditions affecting the quality of qingke wort. The results showed that wort with a high fermentable sugar content, including maltose and glucose, could be obtained using a crushed size smaller than 0.9 mm. Furthermore, enzyme treatment further led to an increase in fermentable sugar content, enhancing the fermentation capacity of qingke wort. Notably, crushing significantly affected the antioxidant properties of qingke wort, with smaller crushed particle sizes yielded superior antioxidant properties to the wort, mainly due to the increase in the content of phenolic compounds such as chlorogenic acid, caffeic acid, and epicatechin.