Effect of Densification Conditions on Specific Energy Requirements and Physical Properties of Compacts Made from Hop Cone

• Main Authors: Niccolò Pampuro, Patrizia Busato, Eugenio Cavallo
• Format: Article
• Language: English
• Published: MDPI AG 2018-09-01
• Series: Energies
• Subjects: Humulus lupulus L.; hydraulic press; compressive pressure; durability; bulk density; specific compression energy
• Online Access: http://www.mdpi.com/1996-1073/11/9/2389

Hop cones, due to their essential flavor, are one of the four main ingredients for beer production. The paper reports the results on an investigation of the densification process of hop cones. This experiment investigated (i) the effects of compression pressure in the range of 40 to 80 MPa and pressure application time in the range of 10 to 40 s on the final density and durability of the compacts made from hop cones and ii) the specific compression energy required for the process. The specific compression energy requirements to compact hop cones ranged from 14.20 to 24.48 kJ kg−1. The final compact density values ranged from 515.2 to 876.6 kg m−3, while the durability percentage calculated ranged from 71% to 91%. The obtained results highlighted that compression pressure—in the range of 40–80 MPa—significantly affects the specific compression energy requirements, the final density and the durability of the produced compacts. In this experiment, pressure application time plays a key role in determining compacts density, while did not affect durability and compression energy requirements. Considering the specific compression energy values calculated in this experiment, it can be stated that the pressure agglomeration method described to compact hop cones is more efficient than pelletizing process which is typically characterized by specific energy values ranging from 19 to 90 kJ kg−1.