Hops are the star in many of the big hits of the modern beer world, from Sierra Nevada's iconic Pale Ale to Feral's Hop Hog and Stone & Wood's Pacific Ale, thanks to their punchy flavours and moreish bitterness. But, for all the t-shirts they adorn, slogans they've inspired and palates they've pleasured, really, what are hops?
In the second of our Beer Basics articles designed to give readers an introduction to beer, brewing, ingredients and techniques, Molly Rose Brewing founder Nic Sandery moves from malt to hops.
What Are Hops?
Hops – or humulus lupulus to use their rather wonderful Latin name – are voraciously growing perennial plants that are commercially trellised up metres-long strings each year to be harvested for their flowers, which look like upside-down pine cones. They grow best between 35 and 55 degrees of latitude in both hemispheres and prefer particular conditions too, typically cold winters, long summer days, flat terrain and shelter from the wind.
Inside these green cones is where the magic happens: if you get one in your hands – ideally freshly plucked from a bine (not vine) – peel back the outer leaves and you'll start to see the sticky yellow lupulin glands wrapped up inside. These contain the oils and resins that brewers are aiming to utilise within the brewing process.
Once harvested, usually through autumn, they are dried quickly and sold to brewers as compressed pellets (most common) or dried flowers. There are other forms too, including hop oils and more recent developments like lupulin powder, sometimes referred to as "hop hash" or "hop crack".
What do hops do?
These oils and resins bring much more to beer than just adding extra fruitiness to your favourite pale ale or a herbal zing to a refreshing pilsner. Aside from delicious flavour and aromas, hops contribute bitterness to balance the sweetness of malt, extra mouthfeel, improved foam and added flavour stability.
How did they end up in beer?
The number one reason hops beat out a range of other foraged herbs as a beer additive more than a thousand years ago is their antimicrobial capacity.
While the earliest recorded use of hops in beer is found in 9th century France, this switch to hops and away from mixed herbs (known as gruit, a term you'll occasionally see used on the rare occasions brewers are creating beers without hops) started to happen across Europe and the UK from around the 12th century. By the 16th century, almost all beers were made using some hops.
It was in this time period that the cultivation of hops really took off and those grown in various regions began to be sought after for their quality in the brew kettle.
How are hops used?
There are two main goals when brewers use hops:
- Extract the desired level of bitterness
- Extract the right flavours and aromas
Alpha acids are a family of compounds found in the yellow, sticky lupulin glands that are responsible for the bitter flavour in beer. In order for these compounds to be utilised in beer, the hops must be boiled. The longer hops are boiled, the more bitter compounds will be extracted.
Flavour and Aroma
I like to compare extracting hop flavour to cooking a spag bol with herbs. You have your woody herbs like thyme and oregano and your fresh, leafy herbs like basil and parsley. You add the woody herbs early on in the cooking process and the flavour integrates into the entire dish but if you try to cook your basil or parsley for longer than a few minutes you lose all of the fresh, bright aromatic flavour you love.
This is just the same with hops. Some are bright and aromatic and punchy and you just need to hold off on adding them until right at the end of the boil; others have a little more staying power and you can integrate them into the beer with a longer boil time.
If you really, really want to get some bright zing and punchy hop flavours and aromas into a beer you can wait until the beer is fermenting in a tank (at between 10 to 25°C) and then throw the hops right in there (called dry hopping). It’s kind of like garnishing that spag bol with a handful of basil.
In recent years, brewers have started adding hops at all times and in all manners to beer throughout – and sometimes after – the brewing process, but the above covers the basics: add hops early in the boil and you'll extract bitterness and "burn off" flavour and aroma; add them later and you'll increase the amount of essential oils in your beer, thus adding hop flavour and aroma.
Why do they all taste so different?
From around the 14th century, hop growing regions had developed in Germany, modern day Czech Republic and England, each with their own distinct characteristics. By the 18th century, hop farming had expanded to the USA, where wild US hops were added into the mix (these hardy plants will continue to grow and spread even untended, and you can find wild hop plants in parts of Australia where commercial growing is long gone).
Plant breeding advanced these unique characters even further. Most of the early breeding that was being done was to increase the amount of the bittering alpha acids available to brewers; these had become something of a commodity as it had been discovered they were the preservative and antimicrobial element of hops.
Traditionally, delicate flavours like spicy, earthy and floral were chased by breeders and any other characters, such as citrus or pine, were shunned as unrefined. This all changed when a certain hop in Oregon, USA, showed immunity to a disease that had wiped out that year’s crop of traditional hops: Cascade.
This was in the 1960s and, while the high cropping rate this new variety offered was attractive to farmers and brewers alike, the flavour was still not favoured and, over time, Cascade production began to decline. That was until a small brewery named Sierra Nevada took a keen interest and the modern American pale ale was invented.
As a result, from the late 1980s onwards, breeding programs in the US started selecting for these “New World” hop characteristics. The breeding programs spread around the world and now we (as beer consumers and hop lovers) have great new varieties coming out of Australia, New Zealand, Germany, France and England.
What do different hops taste like?
Since taste is very subjective, people may disagree with me here but I like to place hops into five categories and this is where your homework will come into it again. (Note: don't lick or eat hops as they're bitter as anything!)
These are traditional European hops, which have delicate and refined notes typically described as spice, earth and floral. The noble hops Saaz (Czech), Hallertau, Spalt and Tettnanger (all Germany) are said to be the most refined of them all. These hops can hard to put your finger on in a beer as they are very subtle and not trendy or cool.
Example: Trumer Pils
See if you can get your hands on a Trumer Pils for a decent whack of noble and other European hops – just make sure it has been stored in the dark*.
These hops are similar to European hops but often have more of a fruity and woody character as well as the spiciness and earthiness. They are also not overly trendy and are more on the delicate side compared to other hop types. English farmers are also responsible for the best name in hops: Fuggles, but other examples include Goldings, Bramling Cross and Bullion.
Example: 4 Pines ESB
Grab one of these to pick out herbal and earthy hop aromas and flavours alongside its bold malts.
When I think classic US hops, I think of citrus, grapefruit, pine and resin and the classic Cs; Cascade, Centennial and Chinook. Also fitting in here are Simcoe, Crystal and Columbus.
Example: Sierra Nevada Pale Ale
If I recommended any other beer here I would be upset at myself. Grab yourself a fresh Sierra Nevada Pale Ale for a look at how much you can do with one great hop. If you want really heavy and dank pine, resin and citrus go for the same brewery's Torpedo Double IPA.
These are the rockstars! They come from all over the world but all have some form of tropical and citrus punch: Galaxy (Australia – mandarin, lychee, mango, passionfruit); Citra (USA – lychee, mango, pineapple, citrus); Amarillo (USA – full on orange and citrus); Mosaic (USA – passionfruit, citrus, stonefruit and mango, often with a "candied" feel); El Dorado (USA –pineapple, melon, stonefruit); Motueka (NZ – citrus and tropical fruit).
Example: Beers using these hops are increasingly common, try to get your hands on a fresh New England style IPA (NEIPA). Or, if your local brewery doesn’t make one, grab a Pirate Life Mosaic IPA and taste the tropical, juicy notes.
The others category is an interesting one as there are some hops out there throwing weird flavours. One recently developed in the States is meant to throw flavours reminiscent of barrel aging… But think of vinous sauvignon blanc and gooseberry from the likes of Nelson Sauvin (NZ), berry and black pepper from Pacific Gem (NZ), red fruits, strawberry and bubblegum from Barbe Rouge (France).
Example: Grab an NZ pilsner, a style popularised by Emerson's, or Kiwi pale like those from Tuatara to taste Marlborough Savvy B in a beer!
There's much more that could be said about hops, with breeders continuously searching for new flavours and aromas and brewers exploring new ways in which to use them in beer, but this is a good starting point from which to launch.
You might like to hunt down Bridge Road's Single Hop IPA Series four-packs to get an insight into how four varieties of Australian hops present differently in what's otherwise the same beer or just pick up a selection of (fresh) pales, XPAs or IPAs to share with mates and see how their fruity, spicy, earthy natures differ from one to the next.
There's also plenty of literature on the subject and you can read more on this site here:
- A feature on the family running Victoria's biggest hop farm in the High Country
- An interview with US hop breeder Jason Perault
- And all manner of stories on wet hop beers, small hop farmers, the history of hops in Australia, the importance of freshness in hoppy beers and more here.
Next up: yeast...
* Green bottles let UV light come into contact with beer, which chemically changes the alpha acids into a new compound that has a flavour often referred to as "skunky" – think of a stale beer garden in summer. So make sure any green bottles have minimal exposure to light!