When selecting hops, the harvest year is
often one of the first criteria brewers consider. A newer crop is commonly
associated with greater freshness, higher quality, and stronger aromatic
potential.
However, hop quality is more complex than
the harvest date alone. Like any agricultural product, hops vary naturally from
one season to another. Besides the growing region, individual settings at the
farmers side, microclimate and many more parameters influence the composition
of hops, that continues to evolve after harvest.
Two key factors must be considered:
· Year-to-year variability,
driven by growing conditions / the mentioned parameters above
· Changes during storage,
influenced by temperature, oxygen exposure, and time.
As a result, the harvest year provides
useful context, but it is not a reliable indicator of quality on its own.
Analytical data and storage history are often far more informative.
1. Harvest year naturally affects hop
composition
Weather conditions such as temperature,
rainfall, sunshine, and humidity directly influence the accumulation of
compounds important to brewers, particularly alpha acids and aromatic
compounds.
It is therefore normal to observe
differences between harvests of the same variety. Research has shown that
climatic conditions can significantly impact bitter acid levels and essential
oil composition, among other parameters such as ratio of certain resin fractions
or more importantly the initial HSI right after harvest.
What this means for brewers
The latest crop is not necessarily "better." For example, the same hop variety may contain 14% alpha acids one year and 11% the next. Brewers simply need to adjust hopping rates to achieve the desired bitterness.
The harvest year describes the growing season, while laboratory analysis reveals the actual characteristics of the lot.
2. Storage conditions matter just as
much
After harvest, the composition of major
substance groups changes over time. The extent of the change in this natural
process depends mainly on storage temperature, oxygen exposure, and storage
duration. The main key to maintain the original crop year’s composition is the
oxygen-free and inert packaging of pellets, followed by cold chain until usage
at the brewery.
Hop Storage Index (HSI)
The Hop Storage Index (HSI) can be used as
one of the criteria to assess hop freshness and storage quality. In many cases,
it provides a better indication of a lot's condition than the harvest year
itself, but still, the HSI is influenced by numerous factors and fixed numbers a/o
limits are not meaningful. Respective remarks have been published by the MEBAK
analytical committee, proposing a « delta HSI « that considers the
increase of HSI for the assessment rather than fixed values [1].
Studies consistently show that cooler
temperatures and limited oxygen exposure significantly slow the hop’s natural degradation
and help to preserve alpha acids and aromatic compounds.
Variety and Product Form
Storage stability also depends on:
· Hop variety
· Product form (whole cones or
pellets)
· Storage conditions
As a result, two lots of the same variety
harvested in the same year can have very different quality profiles depending
on how they were processed and stored.
3. Essential oils
Essential oils are responsible for much of
a hop's aroma. Like the bitter
substances, they may also decrease and change over time, if not handled
properly. Again, processing to pellets is the key to remain the initial quality,
also because of inert, oxygen-free packaging besides ideal temperature at cold storage.
Within the Best before date, no significant changes occur on both, aroma and
bitter substances. Once bags were opened, they should be handled with care, to
avoid any degradation [2].
4. What is the impact on beer?
As unprocessed leaf hops age, oxidation
products such as humulinones and hulupones are formed. These compounds still
contribute to bitterness, meaning that a reduction in alpha acids does not necessarily
eliminate a hop's bittering potential in a notable range [3]. Brewing trials
have shown that well-preserved hops generally produce beers with better sensory
stability. More importantly, the actual condition of the hop at the time of use
has a greater influence on brewing performance than the harvest year alone.
5. How should brewers evaluate a hop
lot?
The most useful indicators include :
· Alpha acid analysis
· Storage conditions and
packaging quality (intense quality checks on the foils and the sealings)
·
Sensory check upon delivery (this
is practical without analytical efforts)
· Get an overview on the crop
year’s performance and the officially launched AHA-alpha acid values which are
usually published shortly after harvest, representing the crop year performance
in a best way. [4]
When multiple harvest years of the same
variety are available, the best approach is to compare them using adjusted
dosages based on analytical data.
Conclusion
Hop quality cannot be judged solely by its
harvest year. Seasonal growing conditions influence hop composition, while
storage conditions determine how well those characteristics are preserved over
time.
The harvest year should therefore be viewed
as background information rather than a definitive measure of quality. For
brewers, analytical data, aroma profiles, and storage history remain the most
reliable tools for evaluating a hop's true potential.
In practice, different harvest years of the
same variety can both produce excellent brewing results. What matters most is
understanding the actual characteristics of the lot rather than relying on the
crop year alone.
[1] https://www.mebak.org/en/methode/r-300-12-110/hop-storage-index-hsi-in-whole-hops-and-hop-products/2619 (02.10.2026)
[4] Example for 2025 : https://brauwelt.com/en/topics/raw-materials/648792-the-alpha-acid-content-of-hops-from-the-2025-crop-year-with-updated-averages-over-multiple-years
For 2026 the update is still pending, will be launched these days !
