New friendships and new methods…as Leuven and Norfolk brewers collaborate

As brew collaborations goes our twinning with Adept Brewing, of Leuven certainly pushed the boundaries!

It was great to welcome Dimitri to Norfolk and to Moon Gazer barn, and the idea of recreating a 16th century Flanders Hoppenbier with a traditional UK mild certainly peaked the interest.  However, as the day went on Dimitri was heard to say “I now know why they stopped brewing this type of beer.”

Its nothing to do with the taste, rather that the technical challenges are many compared to the modern barley-based brews we craft today.

Allow me to explain – in layman’s terms.

Hoppenbiers were made from 100% oats – that was the main cereal crop used at the time, and like the barley we use today was the source of all the good stuff we need for brewing.  Essentially, by steeping in warm water we are looking to extract starches that modify into sugars that ultimately the yeast will convert to alcohol. This steeping process is called mashing in and is carried out in a vessel called a mash tun.

So far so good. The only problem is that with oats – unlike malted barley – the grains want to clump together when we are soaking them.  This makes it really hard to extract the water filled with the goodness  from them. Imagine taking a bowl of the thickest porridge, pouring some milk on the top and trying to get that milk through the ‘cake’ of oats and out of the bottom. That was our challenge.

How they coped with this way back in the 1500s doesn’t bear thinking about. Today, we have some tricks of the trade. One of which is adding in some rice hulls – basically to help stop the oats sticking together. These hulls impart nothing into the water and simply help to create a filter. However, this is not an exact science and is very much a ‘suck it and see’ in terms of how much to use.  Also,  typically brewers today will only use about 15% of oats in a brew.  We were aiming for 67%!  The other 33% was to be modern day barley.

The next challenge we set ourselves was that in Belgium stepped infusion is commonplace – this basically means that they soak the grain at a starting temperature in a mash tun that then has heating elements which can raise the temperature so at each key stage different reactions are happening.

Problem 1 – heated mash tuns are not commonplace in the UK as here we tend to do a single temperature mash. Certainly, that’s all we have at team Moon Gazer.

Problem 2 – oats and barley need to be steeped at different temperatures to release the good stuff!

Oats are optimised by soaking initially at 37C, then rising to no less than 60C.  Maris Otter needs soaking at 64-65C for optimisation.  That’s a temperature rise of pretty much 30C.

Problem 3 – once soaked at the correct temperatures the grain needs taking even higher – to 70C + to stop further enzyme activity.

OK, the short summary…

Problem 1 – easy – oats in, rice hulls in – 37C no problem.

We then added more water at a higher temperature – to balance the whole liquid at the 60C needed. Water added, so far so good. We then circulated the water out of the bottom onto the top to evenly distribute the temperature.  Worked like a dream only we ended up 2C short of where we needed to be. Not helped by the aforementioned oat clumps holding much of the water!

Now that may not sound a lot – but it’s crucial in extracting the good stuff!   Sure enough a quick check of the liquid showed we were about 30% short of the good stuff we needed.

So, time for some out of the box thinking. Transfer the liquid from the mash tun, into the kettle, warm it up and transfer it back to soak the cake.  Care was needed to make sure we didn’t dry out the cake of grain in the mash tun as it would then collapse and be useless.  A tricky and nerve-wracking balancing act.

Fast forward 40 mins and the liquid was back in the mash tun – however we were still 1C short. We had been doing well and the reaction we wanted to happen were happening but still not quite enough.

So, time to repeat the process, and this time when transferring the heated liquid back we added some more Maris Otter a joint decision based on the Belt and Braces hand book!

By this time the malts were smelling amazing and must have felt like VIPS with the amount of TLC they were getting and the good news is we had rescued the grain from 30% under to a little less than 5% under where we needed to be.

This is where having a Belgian brewer on had helped as Dimitiri suggested the addition of Candi Sugar typically used in Belgian brews to make up the final bit of our shortfall.

So, although being 2 hours behind where we expected to be we seemed to have created a base which was smelling like nothing we had smelt before – amazing complexity  of malt flavours.

All that was left to do now was boil, add the hops and pop into the fermenter. Then one final test to see if we had hit our sweet spot.

Thank fully the answer was yes, indeed we were a slight bit over, which added one final unforeseen task, but one which involved a very quick change to the artwork for the pump clip so we could now aim for a 5% abv brew.

What was great is that it pushed the boundaries of our collective minds and also pushed our equipment to new limits – so lesson learnt!  It was also great fun.

Look out for more updates as the beer ferments and matures.

Thanks again to visitflanders for supporting this project.

This and 3 other ales created by other Norfolk and Belgian brewers can be enjoyed at this years City of Ale