MBAA TQ https://doi.org/10.1094/TQ-60-3-0621-01 | 
VIEW ARTICLE
Lindsey N. Rubottom and Thomas H. Shellhammer. Department of Food Science & Technology, Oregon State University, Corvallis, OR, USA
Abstract
Different growing regions, as well as individual farms, have distinct processing and drying demands and/or constraints that influence how hop growers dry hops, including their desired drying temperatures. This review aims to summarize and give insights into the hop growing and processing landscape, with a discussion of the prominent technologies being used to dry hops, what is currently known about their impact on hop quality, and novel hop drying methods being explored in the industry. Generally, there remains room for improvement and innovation in hop drying. Methods currently utilized for hop drying are energy and time intensive and result in inhomogeneity with respect to final moisture content, which impacts overall hop quality. As the U.S. hop market continuously evolves from being historically focused on alpha varieties to focusing on aroma varieties, so too has hop drying evolved. The hop industry’s conventional wisdom is that hop drying temperature significantly impacts hop quality, although research from 2018 to 2023 has found that drying temperature does not impact quality to the degree that was initially predicted. In many cases, drying temperature has a minor to negligible impact, particularly compared with other on-farm parameters, such as harvest maturity, which may have a greater impact on overall hop quality and sensory characteristics. With a refined understanding of which parameters have the greatest impact on hop quality, better hop drying methods can be pioneered moving forward.
