Hop Storage Index

The Hop Storage Index (HSI) is used to describe the freshness of raw hops and hop pellets. The analysis is done by spectrophotometric methods as described in the Analytica-EBC 7.13 and ASBC Hops-12.

Undoubtedly the HSI increases during storage and especially under the influence of higher temperatures and/or oxygen. However, the initial value after harvest is always different and not predictable. Many factors contribute to the initial HSI including varying parameters during hop growth, drying conditions within the hop growers’ facilities and the characteristics of individual hop varieties. As a consequence, the hops of each crop year have a varying initial HSI, even within the same variety.

Chart 1 shows the average data of fresh hops for the current crop year, represented by at least 10 samples.

The above chart clearly demonstrates differences of almost 0.10 between varieties of the main hop growing regions. This year, the highest and lowest values were measured for the two varieties Tradition and Saphir, with a variance of about 40%.

Chart 2 shows the HSI trend of 3 Hallertauer varieties over the last 5 years. The analyses were performed immediately after drying of the hop cones. Whereas the variety Tradition tends to have a similar HSI within the last crop years, Magnum and especially Saphir show huge variations.

Any conclusions about freshness of hops cannot be drawn without considering the annual and varietal influence.

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