Abstract Dry-hopping, which is the cold, aqueous extraction of hops into beer, has gained popularity in recent years as a method for achieving intense hop aroma and flavor in beer. With some brewers dry-hopping at rates up to 2 kg/hL (∼5 lb/barrel), considerable waste is generated in terms of both beer loss and spent hops. The retention of valuable volatile and non-volatile hop components within spent hops, as well as their extraction into beer, was investigated on both a pilot and industrial scale. On the pilot scale (80 L), an unhopped pale ale was statically dry-hopped with differing lots of whole cone Amarillo®, Centennial, and Cascade at a rate of 386 g/hL (1 lb/bbl) for 24 h at 13 °C (55 °F). Spent hop material was also collected from a local brewery that dry-hopped ∼60 hL (50 bbl) of beer at a rate of 1,592 g/hL (4.125 lb/bbl). Approximately one-third of the dry-matter composition of hops was lost during dry-hopping regardless of hop variety; however, there was high retention of both α-acids (77% pilot scale, 52% industrial) and hop essential oil (51% pilot scale, 33% industrial). The oil remaining in the spent hops was enriched in hydrocarbon compounds and depleted in oxygenated compounds. These results indicate that spent dry-hops contain considerable brewing value and have the potential for re-use.

中文翻译：

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干啤酒花的提取效率

摘要 干啤酒花是将啤酒花冷水提取到啤酒中，作为一种在啤酒中获得强烈啤酒花香气和风味的方法，近年来越来越受欢迎。一些酿酒商以高达 2 kg/hL（~5 lb/桶）的速率进行干投，在啤酒损失和酒花消耗方面会产生大量浪费。在中试和工业规模上研究了废啤酒花中有价值的挥发性和非挥发性啤酒花成分的保留，以及它们在啤酒中的提取。在中试规模 (80 L) 中，未酒花淡啤酒与不同批次的全锥 Amarillo®、Centennial 和 Cascade 以 386 g/hL (1 lb/bbl) 的速率在 13 小时静态干投 24 小时°C (55 °F)。还从当地一家啤酒厂收集了废啤酒花材料，该啤酒厂以 1,592 克/小时（4.125 磅/桶）的速度对约 60 升（50 桶）啤酒进行干啤酒。无论酒花品种如何，在干酒花过程中都会损失大约三分之一的酒花干物质成分；然而，α-酸（77% 中试规模，52% 工业）和啤酒花精油（51% 中试规模，33% 工业）的保留率都很高。残留在用过的啤酒花中的油富含烃类化合物，而不含含氧化合物。这些结果表明，用过的干啤酒花具有相当大的酿造价值，并且有再利用的潜力。