Impact of Process Parameters and Bulk Properties on Quality of Dried Hops

Abstract

Hops are critical to the brewing industry. In commercial hop drying, a large bulk of hops is dried in multistage kilns for several hours. This affects the drying behavior and alters the amount and chemical composition of the hop oils. To understand these changes, hops of the var. Hallertauer Tradition were dried in bulks of 15, 25 and 35 kg/m² at 60 °C and 0.35 m/s. Additionally, bulks of 25 kg/m² were also dried at 65 °C and 0.45 m/s to assess the effect of change in temperature and velocity, respectively. The results obtained show that bulk weights significantly influence the drying behavior. Classification based on the cone size reveals 45.4% medium cones, 41.2% small cones and 8.6% large cones. The highest ΔE value of 6.3 and specific energy consumption (113,476 kJ/kgH2O) were observed for the 15 kg/m² bulk. Increasing the temperature from 60 °C to 65 °C increased the oil yield losses by about 7% and myrcene losses by 22%. The results obtained show that it is important to define and consider optimum bulk and process parameters, to optimize the hop drying process to improve the process efficiency as well the product quality.

Special Issue “Advances in Postharvest Process Systems”

“…Food processing technologies include the applications of different physical, chemical, or microbiological methods and techniques to enhance the food quality and also to ensure more diversity for the increasing demand of different consumers. Raut et al [5] discusses the impact of process parameters and bulk properties on the quality of dried hops. The results showed that it is important to define and consider optimum bulk and process parameters in order to optimize the hop drying process to improve the process efficiency as well the product quality.…”

“…This special issue consists of three sections, focusing on food storage and preservation technologies [1][2][3][4], food processing technologies [5][6][7][8], and the applications of advanced mathematical modeling and computer simulations [9][10][11]. We wish to acknowledge the expert contributions of all authors here.…”