hops: please leave your puns at the door

And now for a word on everyone's favourite weed. No, not that one.

To be fair, hops aren't truly a weed, though local varieties do grow wild throughout the world. The hop vine tends to prefer a temperate maritime climate, with mild seasonal variation and plenty of moisture. In exchange for careful tending, it produces tightly-packed cones similar in appearance to young pine cones. Unlike those of their larger conifer cousins, though, the cones stay green and soft until the yearly harvest, when they're picked from the vines for use in brewing.

Hops have only recently become the flavouring staple we're used to in this age of craft obsession; they were originally employed (and remain useful) as a natural sanitising agent due to their high concentrations of “alpha” acids. These stabilise beer throughout its fermentation and maturation by killing off a vast host of potential bacterial and viral contaminants.

When alpha acids are heated above 70C, they gradually isomerise into iso-alpha acids, which provide the familiar bitter flavour behind traditional IPAs and English Bitters, and help to balance out the natural sweetness of the malt. We estimate the concentration of these iso-alpha acids, and thereby the expected bitterness of a beer, using a unit called the International Bittering Unit, or IBU. You'll see IBU numbers listed on every one of our beers if you check out the signs hanging in our cold side.

A Double IPA like our “Prometheus” Campari IPA will have an IBU rating around 75, while our Imperial IPA prototypes hover around the 100 IBU mark. These are clear beers with solid bitter backbones that dry the palate into a crisp finish. At the other end of the scale, our sour beers generally have IBU ratings below 10, as higher amounts would traditionally kill the bacteria employed in the souring process.

The other contribution we derive from hops has nothing to do with sanitation and everything to do with aroma. Packed into each hop cone are thousands of tiny lupulin glands, which contain dozens of highly volatile aromatic compounds ranging from citrus to passionfruit to winter spice. When you taste a great New England IPA (try the LD50 from Balkezes, or Brew Your Mind's Peach Please), most of what you're sensing isn't iso-alpha bitterness, but these potent aromatics, carefully preserved and amplified through every stage of the brewing process. This is much of what makes NEIPAs difficult to brew and pricier than their West Coast cousins: very demanding process requirements and hops dosage rates as high as 25g per liter of beer.

So the next time a barman asks whether you like “hoppy” beers, ask him what he means: bitter or soft, fruity or earthy, hazy or clean.

In two weeks, we'll be wrapping up our brew day introduction with the final hot side stage: the boil! Come back to find out how we control the hops profile of our beers, along with a few other tricks for refining our wort's initial flavour.

making a mash

Yeast makes beer; brewers make wort. Once this sugary substrate is sealed up inside our fermentation tanks, our brew day is done and we can wait for our microscopic friends to finish the job. So how do we get from bins full of crushed grains to sweet, delicious yeast food?

Our tiny hot side is centered around three big brew vessels – a hot liquor tank, a mash tun, and a boil kettle. Those brew vessels are at the heart of every beer we make, and we spend most of any given brew day tending to them, heating and cooling and moving grains and hops and water around on the way to the finished wort.

The hot liquor tank, or HLT, is basically just a staging ground, a 200L pot to hold each specially-formulated batch of water before we combine it with the grist. That said, a lot of thought and work has gone into its construction. Two beefy 5.5kW elements provide the heating, controlled by a beautiful custom panel from Grounded Brewtech which allows us to see and command every aspect of the hot side at a glance.

The HLT is also home to our Heat Exchange Recirculating Mash System, or 'HERMS'. Despite the daunting acronym, this is really just a large steel coil embedded in the HLT, a sealed loop through which we recirculate our brewing liquor during the mash. The HERMS allows us to hold our brew at a constant temperature without worrying about heat loss, and to raise or lower that temperature as we need.


The mash tun is the next step in the brew day. While our grains are milling, we move our 'strike' water from the HLT into the mash tun and begin recirculating it through the HERMS coil to stabilise its temperature. We then add our grains to the strike water, carefully mixing to break up any dough balls. A large perforated filter sits at the bottom of the mash tun, straining out the solid grain husks and grit, and allowing the recirculating water to gently wash the grain.

Anyone familiar with our beers knows that we like playing with high-alcohol and big-body styles (try our “Singularity” Irish Coffee Stout for a delicious example of both!) and for these we need to compromise a bit. Ideally, we'd like a lot of water per kilo of grain, to help the sugars dissolve more readily and improve our extraction rate, but our mash tun only holds 160L in total. So on our bigger brews, more grain means less water, a thicker mash, with lower extraction efficiency and a lot more manual stirring to avoid clogging the mash filter.

After 60 minutes of mashing, the starches in our grain have all been converted, into either fermentable sugars or body-building dextrins which will persist into the finished beer. It's time to move the wort into our boil kettle for the hops additions, but we want to pull as much sugar and flavour from the mash as we can. So as we slowly drain our wort into the kettle, we gently spray hot water over the top of the mash bed; this final rinse is called the 'sparge' and loosens up the remaining sugars to pull them into the boil kettle.

All told, our 25-50kg of grains will end up as roughly 150L of pre-boil wort, and if we're lucky we'll get 75-80% of their sugar content into our kettle. From there, it's time for everyone's star ingredient: hops! See you in two weeks!

water: the secret ingredient

Beer is mostly water, and water is far from constant. If you've ever drunk iodine-purified water in the wilderness, or a smoked beer that smells like a hospital, you already know the importance of starting with good water.

In Budapest, our water filters through an extremely limestone-rich aquifer before reaching our pipes; all that calcium carbonate is great for thermal baths, but it makes for very “hard” brewing water with a lot of dissolved mineral content. For this reason, we have two water supplies at Gravity: a normal tap, and a reverse osmosis filtration system which provides us with 150L per hour of thoroughly de-ionised water.

The tap supply is great for beers with a high proportion of acidic malt, like our triple scotch ale and stouts, but it still requires some care. Municipal water is purified with chlorine and chloramine compounds, which bind to smoked malt in particular to produce chlorophenols, imparting an unmistakable medicinal aroma to the finished beer. For that reason, every drop of water that enters our tanks goes through an active carbon filter to remove chlorine and other contaminants.

Not all our beers have enough dark-roasted, acidic malt in them to handle our tap water, so the lighter-coloured styles depend heavily on our reverse osmosis filtration. This beast of a system pumps municipal water at very high pressure across a membrane with pores small enough to strip out the electrolyte ions and deliver highly purified water into our hot liquor tank.

Once we've achieved the correct balance of tap and de-ionised water, we need to adjust it to the specific profile of our beer. Something as simple as the pH of our wort can throw off our malt extraction efficiency, causing a lower eventual ABV and generally mucking up the rest of the recipe, while individual ion concentrations are critical to the perceived mouthfeel of the final product. Acid, specially-treated malts, and salt additions allow us to regulate all these factors to end up with consistent, delicious results.

Next week we'll be getting into the core of our brew day: the mash. Come back to see how we convert all our carefully prepared grains and water into sweet, delicious food for our yeast!

malt and milling

You can't make good beer from bad ingredients. You can cut corners on equipment, personnel, marketing, and branding, and you'll mostly just cost yourself time and sanity. But start with bad malt, hops, water, or yeast, and your beer will suffer for it.

Aside from water, malt and other grains make up the largest proportion of any finished beer. For a typical 120L batch, we'll get through 25-40kg of malted barley, all of which has been painstakingly sourced, malted, dried, and in some cases roasted before it even gets to us. We make a point to seek out the best malt on the market, but different suppliers specialise in different styles; we tend to use Simpson’s Malt for our English and American varieties, and The Swaen for more continental malts. But what the hell is malt?

Barley, like oats, rye, and wheat, is a seed. Shed from the parent plant, it lies dormant and secure within its husk until spring, when warm weather and rains signal it to release its stores of sugar and grow into a new plant.

Those sugars are precisely what we need for brewing, but in their dormant form are tightly bound up in long-chain starches, protected from yeast and other microorganisms which might penetrate the grain husk. The job of the maltster is to trick these seeds into starting their germination, by introducing heat and moisture to them, and partially convert the long-chain starches into more easily accessible ones.

If you chew some malted barley, you can taste the results of the malting process: although the grain has negligible simple sugars at this stage, the converted starches are now short enough to be broken down by salivary amylase in the mouth, giving the impression of sweetness as they're chewed.

Chewing through 25kg of grain would be both exhausting and disgusting, though, so we need a better way to remove the grain from its husk. That's where our malt mill comes in: by carefully crushing the grain through a pair of steel rollers, it can expose the underlying nutrients at a rate of about 150kg per hour. The intensity of the crush is key – too narrow and it will shred the husk, resulting in a dusty, cement-like mess; too wide and grains will pass through whole, wasting them entirely.

The Scottish whisky industry lives by a 10-70-20 rule, in which 10% of the ground material, or 'grist', is powder, 70% is larger grit, and 20% is intact malt husks. We aim for a similar ratio, and 'conditioning' the malt is key to that effort. In our rather unique case, that means filling a small crop sprayer with water, and carefully misting and turning the malt as we feed it into our mill, to soften the husk and allow it to be slipped off the grain undamaged. The rule of thumb is 2% by mass, so we condition each batch with 500-1000mL of water, depending on the grain mass.

Once our grains are milled, it’s time to transfer them to the hot side to mash in – come back in two weeks to see and hear about it!

building a nanobrewery

As far as we're aware, Gravity is currently the only Hungarian brewery with a production volume under 500L – if you run something smaller, please get in touch, we'd love to chat! – but “nanobreweries” in the 100-250L range are commonplace in more mature brewing markets. The UK, US, and Czech Republic are strewn with tiny brewhouses, from pilot rigs for large breweries to amazing home setups in cavernous garages.

One challenge of this segment of the market is that the small volumes produced haven't traditionally attracted the wealth of equipment options that large production breweries rely upon. Recent years have seen increased attention to the nano scale, but we still just don't have purpose-built hardware for every eventuality.

As a result, our pilot brewery incorporates equipment from several countries, as well as an increasing number of unique solutions we've designed and built ourselves. It's also permanently under refinement and reconstruction – every day we learn new things about our setup and the science of brewing, and when we find a better way of doing something, we implement it.

Gravity's pilot brewery at Rakoczi 29 measures 18 square meters, which is just as tiny as it sounds. We've had to conserve every square centimeter we can, and come up with some creative solutions to the problem of being squeezed into a couple kitchen closets.


Every brew day begins in our malt storeroom, a creatively converted stairwell where we prepare the malt and other grains for the day. From there, we bring our ingredients next door to the 'hot side', where the actual brewing happens. Most of each 6-8 hour brew day is spent here, converting grains, hops, and water into 'wort', the sugary liquid which will become our beer.

Once the wort is complete, we transfer it into our 'cold side', which is the glassed-in row of fermentation tanks you can see from inside Neked Csak Dezso. They're one of our partner bars, along with Kandallo and Hollo es Roka, and receive a keg or two from each batch we make. The cold side houses everything that happens post-boil, from oxygenation and yeast pitching to dry hopping and kegging. It’s all on display, so if you see us in there and have a question about our brew process, feel free to say hello and ask us!

Finally, we have a small merchandise section within the bottle shop at Neked Csak Dezso, with all the usual swag – t-shirts, baseball caps – as well as some very cool custom bits and pieces. Check it out next time you visit!

Thanks for reading, and stay tuned for next time, when we'll be running you through the start of our brew day: malt and milling!

Greg KieckheferComment
welcome to gravity!

Happy New Year from Gravity Brewing, and welcome to our new blog! Since launching 6 months ago, we've been thrilled by the support and interest the community has shown us, and we've been dying to offer you some new insight into the brewery. So from now on, we'll be bringing you biweekly updates straight from the brewery, looking at our equipment, ingredients, new beers, and some exciting new developments for 2019!

From the beginning, then: Gravity Brewing is two guys, Tomi and Greg, who have been homebrewing together since 2015. Tomi was enrolled in a Master Brewer course at the time; Greg just wanted to experiment with styles he couldn't find in Hungary.

In the years since, the Hungarian brewing scene exploded, and our experience gradually grew through dozens of 20L batches, many successes and failures, and of course plenty of parties to drink it all. Inevitably, we decided to build a professional brewery and introduce our beers to the public.

The Hungarian craft beer landscape is dominated by investor-led breweries producing 500-1000L per batch; name a physical brewery and it almost certainly falls into this category (along with a few much larger ones). Many of them produce solid beers, but we find the endless hype-fueled release cycles of these top-heavy breweries exhausting, and we wanted to build a different sort of business.


We were inspired by some of Hungary's phenomenally talented contract brewers, from places like Brew Your Mind and Balkezes, who apply years of careful small-batch brewing experience to everything they bring to production – outstanding beers like Peach Please and GreyJoy don't simply happen by mad chance, they are the result of intensive experimentation and obsessive attention to detail, as well as financial and creative independence.

So Gravity was born from this notion: start small, with no bosses. We set about building the first professional nanobrewery in Budapest, assembled from the best small-batch equipment the world has to offer. As you'll see in future posts, our pilot brewery is an ultra-custom mashup of processes and technologies, not just from different countries but from the often disparate worlds of home- and production-brewing.

Every beer we make starts at that nano-scale: 120L per batch, 4 kegs divided up amongst our partner bars. As a result, our investment in each batch is expendable, we never have to push our product, and we can (and do!) dump batches that don't meet our expectations. At the same time, we can produce enough beer in each batch to elicit the invaluable community feedback that we depend upon for improvement.

That's the core of our pilot brewery, and it's how we aim to continue. We're in this to make excellent beers that real people can afford to drink, not just taste. Let us know what you love and hate, and we'll continue striving to make the next batch our best yet.