2018 ASHS Annual Conference

Hops (Humulus lupulus), a perennial herbaceous plant cultivated primarily in the United States and Europe for its mature cones, are an essential ingredient to the production of beer. Like many other fresh horticultural products, hops require drying post-harvest to preserve quality and allow for successful long-term storage of plant material. Increased demand for hops has resulted from growth in the popularity of highly-hopped beer styles coupled with increased production of craft beer. As a result, small-scale (0.1 to 0.2 ha) hop farms have become established in many non-traditional hop production regions. Given their small size and limited economic resources, small-scale farms may not have ability to construct or purchase a traditional hop drying facility, known as an oast. As an alternative, small-scale hop farms dry hops utilizing a variety of mechanisms to include ovens, fans, and food dehydrators. Although effective at drying hops, popular small-scale hop drying methods may reduce hop quality. To assess the impacts of drying method on visual quality of dried hops, 54 hop samples comprised of two hop cultivars, ‘Cascade’ and ‘Neo1’, were dried by convection oven, through application of cool air, or by passive evaporation on 21 June 2017. Visual quality of hops pre- and post-dehydration was quantified using a colorimeter. Hops dried by either convection oven or movement of cool air reached targeted moisture content within 24 hrs, whereas hops dried passively required 72 hrs before reaching adequate moisture content for storage. Oven dried hops had significantly (P<0.001) lower hue and were lighter (P<0.05) in color than those dried by either application of cool air cool air or passive dehydration. Changes in hue were significantly greater (P<0.05) in ‘Cascade’ than ‘Neo1’ regardless of drying method utilized. Results indicate that greater visual quality of hops is maintained when dried using movement of cool air or allowed to passively dehydrate. Given the 3-fold increase in time required for passive dehydration, application of cool air is likely the most efficient way to dry hops post-harvest while maintaining high visual quality. Additional research, however, is needed to better understand the influence of drying method on hop oil quality to maximize both visual and consumptive quality of hops.