Development of a coffee beer brewing process using coffee

The purpose of this study was to develop the optimal timing and ratio of coffee inputs in the coffee beer brewing process. Coffee beans used in the process were extracted and used in a leaching manner with a ratio of 1:2.8 between coffee beans and water. The wort and coffee were combined in ratios of 1:1, 1:2, and 2:1 before and after heating, and then fermented at 20°C for 5 days, aged at 20°C, and stored at 4°C for 7 days for comparative analysis. The final pH and brix of coffee beer were 4.81-4.92 and 3.35-4.93 °Brix, respectively, and the total acid and reducing sugars were 0.55-0.74% and 0.39-0.52%, respectively, showing a significant difference from the control group (CG). The alcohol content of coffee beer was 5.5-6.0%, the European Brewery Convention (EBC) was 86.66-493.33, the bitterness was 5.15-7.22 BU, and the yeast cells were 4.89-5.39 log CFU/mL. The content of caffeine in coffee beer was 0.00-1.74 mg/L, and that of chlorogeffffnic acid was 0.00-3.39 mg/L. Based on the physicochemical analysis, the AB3 brewing process, which showed results similar to CG, was determined to be the most suitable.