Explore the world of hops.
Monday 03 August 2020
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Ah, hops. If there’s one material change that’s defined craft beer as a movement since the 1980s, it’s our relationship with the mighty humulus lupus. You can read Matt Curtis’s excellent piece on page 37 for a fuller picture of how the early Californian pioneers seized on their punchy local varieties to inject a bit of vim into time-honoured European styles; for now though, we’re going to concentrate on the plant itself, how it’s developed and why it’s become a source of fierce regional pride for the areas in which it grows.
First, apologies to any long-standing readers who may have heard some of this before. It’s been a long while since we went over the basics though, and we want new readers to fully understand the magic of this wondrous botanical oddity.
The hop plant itself is a member of a very small group, in which its closest relative is hemp or cannabis. Botanically speaking, it’s a very unusual plant, in that its cone – the bit that interests brewers – is actually a modification of the branch that holds the flowers. It is not, as many assume, a fruit and does not result from pollination. The biological purpose of the cone is to disintegrate at the correct time of year (the plant is sensitive to day length) and disperse its seeds to the wind.
Because hops are sensitive to day length, they can only be grown in certain parts of the world. As well as different latitudes, each country where hops are grown has a different climate, so varieties of hop tend to be highly regional. It’s possible to cultivate non-native hops, but they either grow poorly or take on different characteristics; Centennial, for example, is grown extensively in both the US and Europe, yet the US specimens are far higher in alpha acids and aromatic oils.
Hops grow on tall stalks called ‘bines’, which are encouraged to climb poles and create a lush, green canopy several metres high. They are notoriously high-maintenance plants, needing active, season-long management to fight off the numerous pests and diseases to which they are susceptible.
It’s important to get the harvest date absolutely spot on, so the hop cones have a chance to develop properly without tipping over into ruin (which can happen very quickly). The rule of thumb us that the harvest traditionally should be complete before the autumnal equinox, in time for a festival of celebration and thanks.
Once harvested, hop cones will begin to compost very quickly, changing from green to brown and breaking down into an earthy, vegetal mess, in much the same way as cut grass. To prevent this, they need to have air circulated through them while they’re transported to an (ideally nearby) ‘oast house’ where the hop cones are stripped from the cut bines and gently dried to around 12% moisture.
Even though our dried hops now won’t rot, those all-important, flavour-imparting compounds are far from safe, as they’re highly vulnerable to both oxygen and ultraviolet light. To protect them (and make them easier to handle) – at this point they have lots of volume but little mass, like green snow – the whole cones are either pressed tightly together, or crushed down into pellet form. In either case, they are usually sealed in UV-resistant packs to keep them more-or-less inert until they’re ready for the brewer’s expert hand.
So why go through all this faff? How did these bitter, temperamental bits of shrubbery become an indispensable ingredient in the beer we love? Initially, it was for their anti-microbial properties, which allowed brewers to keep their beers from going sour for much longer. For centuries, British Beer was sour rather than bitter, as unwanted bacterial infections ran rampant in ways that would make cask ale lovers weep into their perfectly-kept pints.
The introduction of hop plants from Belgium allowed us to replicate the techniques they had long understood. Not only did the hop largely put a stop to sour beer, it also imparted a wonderful bitterness to balance the sweetness of good British malt and, most importantly, grew very nicely on this side of the channel.
Deliberate cultivation has continued over the centuries, and in recent times has taken an ever more scientific approach, as hop developers seek out new varieties and selectively breed for the characteristics that growers and brewers want: flavour, aroma, resistance, yield and – increasingly – novelty. For example, you can read about the great work being done by Simply Hops on page 14.
This process has been made much more interesting by the rise of craft beer, as brewers and drinkers clamour for new hoppy experiences, particularly from so-called ‘aroma’ hops; those varieties that don’t necessarily add bitterness in the boil, but are deployed in the whirlpool or dry-hopped to add layers of zesty, fruity goodness.
Whether they come from the classic European hop gardens, from the US, South Africa, Australia or New Zealand, our hops have never been as diverse or as exciting.
With its cool summers and high rainfall, the UK is at the northern edge of the hop-friendly zone. Nonetheless, we are home to some truly classic and internationally prized hops, including Fuggle, Ernest, Bullion and East Kent Goldings. While they’re not as in-your-face as their New World counterparts, they can offer subtle and delicious spice, dark fruit, earthy and honey notes.
US hops are much higher in alpha acids and volatile aromatic oils than the European varieties that had traditionally been prized by brewers. This gives a punchy and in-your-face palette of characteristics to play with, from mango and grapefruit to sharp, piney resin. These are the flavours that have defined the craft movement for decades and continue to set our expectations of, in particular, IPA. The innovation continues apace too, with Sabro – the latest must-have hop out of California – making waves across the world.
A real rising star in the hop world; brewers are clamouring to experiment with South African varieties at the moment, including the fantastically versatile and flavoursome African Queen. This demand has been further fuelled by the fact that, several years ago, a certain beer multinational bought up almost all of the country’s production capacity. Obviously, this has been like a red rag to a bull for the craft crowd.
The traditional home of hops, Europe is known for its subtle and elegant hop varieties, full of restrained spice, herbal and grassy notes, and well-defined bitterness. The continent continues to innovate and surprise though; outside Germany and the Czech Republic, Slovenia has risen to prominence, with it superb development programme and distinctive, floral Styrian hops.
Australia, and particularly the island of Tasmania, is as close to hop heaven as you’ll find. Lots of sunshine, rich soil and just enough water make it suitable for growing high-alpha varieties from other countries, as well as its own amazing creations. Galaxy is without doubt the pick of the bunch, and is much sought after on these shores for its incredibly fresh citrus, peach and passionfruit-bearing oils.
Kiwi hops have been riding high for years now, offering brewers entirely new fruity, floral characteristics to play with. Nelson Sauvin is probably the best known here – with its unmistakable white wine freshness – but other varieties such as Waima and Moteuka are increasingly making their way into our fridges, much to the delight of all the Beer52 staff.
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