Abstract Storage conditions play an important role in maintaining the integrity of hop products during processing, transport and storage, and their ultimate quality when used to brew beer. Several groups have investigated variation in alpha acids, beta acids and polyphenols under different storage conditions, but there are few studies directly linking changes in hop acid composition under pro-oxidative conditions, to either: (i) industry standard measures of the oxidative quality of hop alpha acids (hop storage index [HSI]); or (ii) changes in the volatile composition of hops. The aim of this work was to present useful information regarding the variation in hop acids and volatiles in different storage conditions, such as temperature and exposure to ambient air. A comparison between pellets and pressed hop flowers was investigated. Long term storage in oxidizing conditions can lead not only to a decrease in the essential oil content, in particular at the expense of the more volatile fraction, but also to the degradation and/or transformation of some of the main compounds to their oxidized forms. With this work, we hope to give some insight into the inter-relationship of measurable hop quality parameters (such as HSI, hop acid chemistry and volatile chemistry), as well as demonstrate how easily hop chemistry can be affected by improper storage conditions.

中文翻译：

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啤酒花 (Humulus lupulus L.) 储存期间挥发物的变化

摘要 储存条件对保持啤酒花产品在加工、运输和储存过程中的完整性以及用于酿造啤酒时的最终质量起着重要作用。几个小组研究了不同储存条件下 α 酸、β 酸和多酚的变化，但很少有研究直接将促进氧化条件下酒花酸成分的变化与以下任一方面联系起来：(i) 氧化质量的行业标准测量啤酒花α酸（啤酒花储存指数[HSI]）；(ii) 啤酒花挥发性成分的变化。这项工作的目的是提供有关酒花酸和挥发物在不同储存条件（例如温度和暴露于环境空气中）变化的有用信息。研究了颗粒和压榨的啤酒花花之间的比较。在氧化条件下长期储存不仅会导致精油含量降低，特别是以挥发性更强的部分为代价，而且还会导致一些主要化合物降解和/或转化为其氧化形式。通过这项工作，我们希望深入了解可测量的酒花质量参数（例如 HSI、酒花酸化学和挥发性化学）之间的相互关系，并证明酒花化学很容易受到不当储存条件的影响。