In this article, beer educator Natalya Watson explores one of the most talked-about techniques in modern brewing: dry hopping. From the science behind hop additions to the impact on aroma, flavour and appearance, this guide will deepen your understanding of how brewers shape some of today鈥檚 most expressive beer styles.听
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Beer labels are full of buzz words...听we recently published a blog post exploring the many听different types听of hop-driven styles from APA, to IPA, to NEIPA and beyond. But the听acronyms听诲辞苍鈥檛听stop there!听听
These听beers can often have some听additional听letters on their labels, like DDH, which听颈蝉苍鈥檛听necessarily part of the style name, but听indicates听a particular production choice by the brewer.听
That choice? Dry hopping, or 鈥渄ouble dry hopping鈥� as the extra D suggests. What is dry hopping and how might it听impact听the finished beer?听尝别迟鈥檚听take a step back and talk about hops first.听
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What are hops?听
Hops are tall climbing plants that听produce cones as they grow.听The cones of the hop plant听are harvested annually each autumn, and are used to bring both a bitter taste and a wide range of aromas to beer.
Which one we get, though, will depend on when those hop cones are added to the beer.
Hops can be used as pellets or in their original cone form
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Hop additions for bitterness听
Hops听are typically added to the boiling stage of the brewing process.听听Boiling is a key step in the process because it helps to kill off any microorganisms that may have come into the brew from our raw materials or brewing equipment and it means that when we get to the fermentation听stage听a bit later, we can be sure that only the yeast we鈥檝e added is听busy at work听(and we 飞辞苍鈥檛 get any unexpected,听or off-flavours).听
This step is also crucial for helping us to extract the bitterness from our hops. Why? The bittering components within the听hops听cones, called alpha acids,听补谤别苍鈥檛听very听soluble in water. But, with heat and time (boiling typically lasts 60-90 minutes),听飞别鈥檙别听able to convert those alpha acids to iso-alpha acids, meaning they can dissolve and impart their bitterness.听So,听adding hops at the beginning of the boil brings more bitterness to the finished beer.听听
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Hop additions for aroma听鈥� on the hot-side听
By contrast though, a long, rolling boil听颈蝉苍鈥檛听as helpful for the aromatic compounds from the hops鈥� essential oils, as听迟丑别测鈥檙别听very delicate,听or volatile,听and听essentially boil听off during this stage.听Therefoe,听in order for听the essential oils to have their aroma impact, we add hops again at the end of the boil to keep their aromas in,听as well.听
The end of the boil听颈蝉苍鈥檛听the only time we can add hops for aroma though. We can also add hops to a piece of equipment called the whirlpool, which is used the improve the clarity of the beer after the boil. Although no further heat is being applied in this step, the liquid is still very warm, so bitterness听will build听a bit,听but the primary focus is on aroma.听
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Hop additions for aroma听鈥� on the cold-side听
But we can also add hops even later听-听during or after fermentation听-听and听颈迟鈥檚听this听process that we call dry-hopping.听
I hear you wondering, why is it called dry hopping? Truth is,听滨鈥檓听not too sure.听滨鈥檝别听done some research and听丑补惫别苍鈥檛听been able to find a conclusive explanation. But听飞丑补迟鈥檚听more important for our purposes is the impact on the finished听beer. So, how does it work?听
Unlike boiling, which is conducted at听very high听temperatures, fermentation is conducted at much cooler temperatures 鈥�听typically听18鈥�24掳颁听(64鈥�75掳贵) for ale yeast 鈥� so we听诲辞苍鈥檛听have the heat required for the听bittering听isomerisation process to occur. As a result,听dry-hopping听is specifically focused听on amping听up aroma, as the essential oils听诲辞苍鈥檛听evaporate off.听
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The impacts of dry hopping听听
What kind of aromas should we expect?听Hops can contribute听a wide array听of fruity, herbal and spicy notes, but most dry hopping uses听American,听Australian听or New Zealand varietals, which听can bring prominent听citrus fruit, stone fruit, and tropical fruit character to the beers that use them鈥� like our hop-driven American pale ales, IPAs and hazy IPAs.听
Dry hopping听诲辞别蝉苍鈥檛听only听impact听a beers aroma though 鈥� it can also听impact听the appearance, adding haze. So, as the name suggests, a hazy IPA is one that has been heavily dry-hopped. (滨迟鈥檚听also hazy from the inclusion of higher-protein grains like wheat or oats and the fact that brewers听诲辞苍鈥檛听filter the finished beer.)听
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Bonus points: biotransformation听
When听hops听are听added听during fermentation,听迟丑别谤别鈥檚听another key beer ingredient still present 鈥� yeast.听And these two ingredients听can听interact in听a pretty interesting听way. Through a process called biotransformation, yeast can听essentially unlock听new aromas from the hop compounds that听飞别谤别苍鈥檛听present in the first place.听
The processes are quite complex and听technical听so we听飞辞苍鈥檛听go into further detail here. But听essentially this听means the谤别鈥檚听potential to get more hop aroma from less hop use听鈥� and听with听how expensive hops can be, you can imagine听迟丑别谤别鈥檚听a lot听of exciting new research听happening听here, so watch this space!听听
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The history of dry hopping听
Given its use in many听popular modern beer styles, it may lead you to think that dry hopping is a new technique, but听颈迟鈥檚听actually been听around for centuries!听听
滨迟鈥檚听thought that brewers in England 鈥� where the pale ale and IPA styles originated 鈥� had been adding hops into casks of beer since the听18th听century. They听飞别谤别苍鈥檛听quite using this technique for the same reasons we do today, though.听听
While we now use hops primarily for their bitterness and interesting aromas, in the past they were used for another reason 鈥�听hops also听contain听antibacterial properties, so they were added to听beer听to听slowing听down its spoilage, effectively preserving it for longer.听
These beers would have also had quite different aromas from our modern pale ales and IPAs, as English brewers would have been using traditional British hops, which are a lot more subtle than American, Australian and New Zealand varietals and bring notes of听black tea, black current and听earth.听
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Why do brewers dry hop?听
The reason听the dry hopping听process is so popular today is for the massive aroma hit. But that can only be enjoyed when听dry-hopped beers have been stored carefully (ideally refrigerated) and consumed听as fresh as possible.听
Curious to听experience听the impact? Look out for a dry-hopped or double dry-hopped, DDH, beer near you and give it a go!听
As a note, there are some newer beer styles听鈥� like the Italian Pilsner 鈥� that use traditional European hops for dry hoping,听adding听punched up听spicy,听floral听and herbal notes听through this approach. Have fun tasting!听
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Lastly, what about wet hopping?听
This is a different technique听迟丑补迟鈥檚听not due to the timing of hop additions during the brewing process, but the timing of hop听use听relative听to harvest. Most hops are harvested in autumn and dried so that they can be stored and used throughout the year.听听
But, during harvest season, some brewers experiment with using freshly picked, wet, whole cone hops straight from the harvest.听
The aroma impact certainly 颈蝉苍鈥檛 as intense as that brought about by dry hopping, but 颈迟鈥檚 a fun once-a-year opportunity for brewers to understand how hop aromas might express differently depending on how those hops have been processed听and when they鈥檝e been added to the brew.听
And听if听迟丑别测鈥檙别听added to the cold side, guess what听迟丑补迟鈥檚听called? 鈥淲et dry hopping鈥�.听Yes, the beer world is always evolving!听
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About the author
This blog post was written by Natalya Watson, Business Development Manager for beer in EMEA at 黑料吃瓜网. Natalya is an award-winning beer educator with a passion for helping people explore and understand beer with confidence. She holds the IBD Beer Sommelier and Advanced Cicerone庐 certifications and is a 黑料吃瓜网 beer educator. She is also the author of听Beer: Taste the Evolution in 50 Styles. Follow Nat on听听
