Homebrewing a Robust Porter

It took months of research, tasting as many craft beers as I could lay my tastebuds on, to figure out what and why I do and don’t like (I’m still not sure). The aim: decide what to brew.

Last week I assembled the all-important mash tun and procured the other pieces of equipment and ingredients. No more excuses not to brew.


Differentiating factor: Made with Wemmershoek River water

First consideration was water.

Having brewed with only extract before, I’ve never really had pH levels of a mash to worry about, but I learned that the wrong pH can lead to poor mash efficiencies.

I live on the banks of the Wemmershoek River and I wanted to use water directly from this river.

The pH level is an unknown though. I’ve been unable to get my hands on testing equipment, so in lieu of yet more delays, I scooped a bucket of clear Wemmershoek River water and hoped for the best.

Bill, Grain Bill

First time measuring and assembling a grain bill.

Marty Nachel’s Trans-Porter Robust Porter recipe (from Homebrewing for Dummies) forms the basis for my brew, modified for available ingredients.

I used BeerSmith to tweak the recipe to maintain the style parameters, and then scaled it down for the 4.5 litre fermenter I’m using for my little micro-batches of homebrew.

In the end the modification called for 1kg of Pale Ale Malt and a 100g each of Special B, Black Patent and Roasted Barley Malt. Not quite the ratio of the original recipe, so hopefully it will turn out palatable.

Based on the profile I assembled in BeerSmith, the beer is true to the style of a Robust Porter with OG, IBUs and estimated ABV all within range. The only thing slightly over is the colour, which at 58.6 SRM is darker than the upper 35 SRM desirable for the style.

I was actually aiming for a hue similar to Guinness – apparently black, but actually a ruby red when held to the light. Not sure this beer will have any red in it.

Mash In

Grains mixed in with the water. Settled at the perfect temperature. But big remaining empty space bamboozled my temperature calculations - it cooled down too fast.

The river-water was boiled before using it for the mash, so by the time the grains were weighed, the water in the hot liquor tank was 78°C. The pour into my homemade mash tun trimmed it to 75°C, which was perfect for the grain addition.

The grains were diligently stirred in to prevent grain clumps and ensure an even, well-soaked mash. After a good stir the mash settled at a perfect 68°C.

Now the temperature just had to be maintained for an hour. Some homebrewer setups lose just 1 degree over the course of an hour, but my cheapish mash tun is nowhere near as efficient. I wrapped it up in a blanket for what it’s worth.

Not sure which is more challenging: brewing in the tropics or brewing in winter climates

Half an hour into the mash I checked the temp. It had dropped to 65°C, which is the lower end of the ideal temperature range. Stirring in about 1.5 litres of 80°C water raised the mash temperature back up to 67°C.

I figured it would hold for the next half hour and put some extra insultation on the tap assembly, which had become quite hot and contributed to my heat leak.

Mash Out

Spent grains - got a decent yield from mash

At the end of the hour the mash tun was unwrapped to find the temperature just about 65°C.

It was time to mash out. The addition of even hotter water raised the mash temp to around 76°C to stop the conversion process and ready the wort for draining.

The challenge at the draining stage is to avoid a stuck mash, that unnecessary hassle, caused by running off the wort too quickly, compacting the grains in the mash and preventing the free flow of wort. The antidote is patience.

My patient, slow draining of the wort paid off and 30 minutes later my mash had yielded somewhere between 6 & 7 litres of wort.

I took a sample of the pre-boil wort for a gravity reading. It was 1.042, which was just 0.003 off from the 1.045 BeerSmith had estimated for my recipe. A good result.

A little something extra I tried here was First Worth Hopping. I added some of the finishing hops to the brew kettle when collecting the first runnings, which will hopefully impart a hop character to the beer that they say can’t be added in any other way. We’ll see how that works out.

To the Boil

I was going to use the pot on the left, but then my neighbour offered the unused pot on the right. Bonus.

I was gifted a big pot from a neighbour who said it was too thin and burned most things she cooked it in. I heeded the warning, but planned to stir my wort diligently throughout the boil anyway.

The 12 litre pot is perfect for my micro-batches as it leaves a generous space to contain any uncontrolled excitement of the wort during the boil.

I had a few boil-overs with my extract brews, which I boiled in undersized pots. Not only do boil-overs waste precious wort, but they create the mother of all messes.

There would be no boil-overs with this brew.

Lots of space in the brew pot - boil-overs be gone!

I got the wort up to a rolling boil, lowered the flame to keep the boil going without excessive heat and stirred the wort every 5 – 8 minutes to ensure no burning-on occurred.

My hops were added per schedule: Northern Brewer at 60 minutes, and Fuggles at 30, 15 and 5 minutes. The kitchen scale I use isn’t super accurate, so I weighed as close as I could and roughly estimated the relatively small amounts I needed.

In lieu of hop-socks, which I previously used for my hops additions but seem to be unavailable here, I added the hops directly to my boil. The hops all but dissolve in the boil and is hard to extract afterwards without a filter of some sort.

I’ve found that chilling beer makes most suspended particles drop to the bottom and I was hoping I could cool my boil sufficiently to achieve this effect with the hops, otherwise I’d have to run it through a strainer – not ideal.

Ridiculously small additions of hops were required. Almost too light for my scale.

After slightly more than an hour the boil was complete and had reduced to just about the perfect amount for the fermenter.

My batch is still small enough for an ice-bath to cool the kettle rapidly enough to avoid any complications.

The benefit of living next to a river is that the water from the taps, especially at this time of year, are ice cold. I dipped my pot in a bath of ice-cold water and while stirring the water in the bath clockwise, I gently stirred the wort anti-clockwise. Thanks to frigid water and a pot with very thin walls, my boiling wort had cooled in less than 7 minutes.

Pitch the Yeast

Just after I started the boil I took my packet of dry yeast from the fridge for it to gently thaw in preparation of joining the other beer ingredients.

Halfway through the boil I added the yeast to a cup of cooled, boiled water to make a slurry to pitch into the cooled wort. I forgot about the scale of my recipe and now I’m not sure if I should have used less yeast. I’m unsure how this will impact the brew.

The cooled wort was vigorously poured into the sterilised 4.5 litre fermenter. It splashed a lot as it went in, replacing all the oxygen lost during the boil for the yeast that needs it to do its part.

I filled the fermenter perhaps a little too high, and was left with about 600ml of wort in the pot. Thanks to the cold water and perhaps the stirring, most of the hops had stayed behind and the fermenter was pretty much particle free.

It remains to be seen how clear the brew will be in the bottling bucket after I rack it over post fermentation.

I took another hydrometer reading before pitching the yeast, and the starting gravity of the brew is 1.052, slightly lighter than what was expected, but close enough (photo is a hot sample of the pre-boil wort).

This was actually a hot measurement of the pre-boil wort. At higher temps the hydrometer reading is lower than expected - correct temp for hydrometer readings is 15C.

The last bit of space was reserved for the yeast slurry, which was added with gusto. The fermenter was filled to the brim, virtually guaranteeing a mess when the fermentation starts, so I put the fermenter inside the clean brew pot to mitigate what would come.

The ambient temperature was about 20°C, but here it drops to around 5°C at night. I didn’t really think through the low temperatures.

The fermenter was set at 15:33 and I got ready for the MyBeer event later that night.

When I returned home at about 22:40 – the brew was fermenting furiously, already standing in a puddle of wort, the path of how it ended up there marked by a rocky trail of bubbles coming out of the airlock.

It would continue for the next 2 days, but then slow down on the 3rd day, mostly, I suspect, due to the cold. The fermenter was cold to the touch and undoubtedly much than the lower limit for the ale yeast I’m using.

I’ve moved the fermenter to the hottest part of the house, with insulation to for when the sun goes down. I will have to find a way to keep future fermentations at a stable temperature. I’m thinking a hot box with a light might do the trick.

The brew will stay in the fermenter until Thursday, at which point I will transfer it to bottles, where it will stay for another 7-10 days before being ready for to drink.

A fermenter full of what will hopefully be an interesting Robust Porter.

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