Optimization of Technological Parameters of the Dry Hopping Process With the Development of a Methodology for the Integral Assessment of the Quality of Beer
The development of craft beers with complex fruit, floral and citrus tones, the search for an original taste and the revival of old recipes are the prerequisites for the use of dry-hoping in the brewing industry. The dry-hopping process was carried out dynamically in an experimental setup with a hop apparatus, screen filter, fermentation tank and pump. Saphir and Chinook hops were used. The study included determination of physical and chemical parameters of beer: concentration of humulinones, iso-a-acids and a-acids; total content of polyphenols; pH; volume density. Sensory evaluation indicators included: hop aroma intensity and quality; flavor fullness; bitterness quality; and overall preference. Radial neural networks were used to approximate the results of the study. Optimal process parameters were determined: Saphir hops, process duration 12 hours, temperature 3,0 °C. The optimum process duration is 10,5 h and the optimum temperature is 3,0 °C. Processing temperatures below 3.0 °C result in a slightly lower optimization criterion than the 3.0 °C processing temperature. At temperatures of 1.5 and 2.0 °C the optimum process duration is 8.15 and 11.25 days respectively. The use of the combination of Saphir & Chinook hops offers no improvement in the overall optimality criterion compared with the use of Saphir alone. The process duration of 4 hours achieves an optimization criterion of more than 0.60, but only with durations of around 12 hours does an optimization criterion of more than 0.65 become attainable.