Sticky yeast

My yeast is stuck again. It's fermented about 3/4 of the sugars into alcohol and decided to stop. Most inconsiderate and inconvenient of the little fellas.

I've got a 'to do' list to fix it, many of these tricks will probably apply to the keen home brewer too.

1. Add oxygen (but I don't think it's that - added loads of oxygen after learning from last time)

2. Give it a good ol' rousing. The yeast I'm using forms a lovely yeasty-Carbon dioxidey-beery foam on the top but doesn't really swim around in the beer very well. Mixing it up (with a very sterile stick!!) gets some of the yeast back into the beer.

3. Give it a zinc hit. Zinc is vital for yeast growth and fermentation. Often if your beer is stuck at a higher gravity and won't budge, a little zincy hit will liven it up.

4. Re pitch it. This is a last resort (mainly because I've not got any more buckets of yeast lurking in the fridge) and it shouldn't really need it as we put loads of yeast into the beer which is more than enough for fermentation. Why add more than needed? Skimming over the subject...

I've roused it and added a zinc booster, all I can do now is wait.... I'll keep you posted.

In tip-top condition

Before I start, here's a quicky for those who don't know what bottle conditioned beer is...
Basically its replicating the cask conditioning stage where a little bit of yeast is left in the beer to ferment a little more of the beer. It adds far more character and develops flavour, as well as makes the beer a bit more lively. This is called secondary fermentation and is what makes real ale, real. In a bottle, you encourage roughly the same process, although you often add a weenie bit of sugar as tasty food for the yeast. Normal bottled beer is filtered and so doesn't have any yeast which means this process doesn't happen. Often you can have both cask and bottled versions of the same beer and they taste totally different. Also, bottled beer is often brewed else where, a bit like baking a cake in a different kitchen. In theory they're the same beer but in practice they may be quite different.

We're going to bottle condition some of our beer for the Welbeck Farm Shop. Also, as of this weekend, we'll be having a cask of beer in the shop to sell fresh beer in 4-pint carry kegs (you should go and get some).

But I've never bottled beer before. I know the theory but am not really sure about the nitty-gritty business...

The question is, if I bottle condition a pale ale at 4.3% ABV, will it indeed be in tip-top condition?
Will it ever drop bright or will it be cloudy?

Apparently above 5% is a good guide to go by, because you need a higher alcohol content to make sure the yeast settles out at the bottom of the bottle to give you a clear beer.
I could do a lower ABV but very dark beer because you wouldn't be able to see if it wasn't crystal clear, but then that seems a bit like cheating.

Also, this priming business with the beers (which means adding a teeny tiny bit of sugar for the yeast to munch on). I'm a bit apprehensive about it because it's very easy to under prime which means you don't really get much conditioning, but equally you can over prime.

Last night I had a bottle conditioned beer which was really gorgeous. It was a bitter brewed with crystal malt, roasted barley, and black (or chocolate?) malt (so my excitable taste buds tell me). It was only 3.8% and quite pale. When I opened it it fizzed all over me and the kitchen for about a minute! I'm presuming this may be a case of over priming, and you could see it wasn't quite clear either, but I didn't really care because it was scrummy.

Running this brewery is a very very steep learning curve to say the least. All advice gratefully received.

Oh, and I'll find the name of that beer, but I have given the bottle to my avid home brewing friend already! Also whilst we're on bottle conditioned stuff, I tried the Marstons Very Special Old Pale a couple of weeks ago, which was rather good. It's available at Morrisons I think.

Small Beer

Small beer. A beer for small people? This is something I was reading about the other day, and being a fan of brewing history, thought I'd share it with you. Apologies for not blogging FOREVER by the way, been terribly busy!

From what I gather, a 'small beer' was made from the second sparging of the original mash. What does that mean? After the barley grains were steeped in hot water and this liquid was collected it was used to make a strong beer. The soggy grains left would then have more hot water put through them to get as much of the remaining sugar out. This second lot of sugary water was then used to make a second, very weak beer.

So who drank this really weak beer and why did they even make it? The history of brewing dates back thousands of years when sanitation was poor and nasty water-borne bugs like cholera killed many people. It was known that the process of brewing involved boiling the water and adding hops which have antibacterial properties, which effectively made the water potable.

The problem was that to drink this 'safe' beverage all day, its consumers would quite probably end up trolleyed as it was high in alcohol content - not particularly conducive to a productive day. The medieval solution was a home-brewed 'small beer' which was given to children, women, and labourers. It was usually under 2%, and often under 1%ABV which meant it served the purpose of hydrating without intoxicating. Marvellous.

I fancy making a small beer. Make a lovely barley wine with the first runnings and then make a really low alcohol 'small beer' with the second. Maybe one day...

PS Apparently 'small beer' was also something to do with porridgey stuff which I don't understand, and it's also a term use to be mean about modern beer which tastes a bit like dishwater.

Part Maths, Part Art, Part luck.

After the last hop addition, the wort is finished and ready to ferment with the tasty yeast. We transfer it all to the fermenting vessel, leaving behind the squashy hops. It's dead important that the sugar content (specific gravity, or just gravity) of this wort is spot on, because it's the sugar which yeast turns to alcohol and we need the beer to be the correct ABV (we'll have worked this out before hand to use the right amount of malt etc). Boiling wort serves several main purposes, including developing hop bitterness, getting it clear, caramelising the sugars, and reducing it to enhance all the flavours.

After doing this, the gravity can often be to high because so much water has been evaporated. To correct this, we'll need to dilute it before fermentation. This dilution is called a 'hop sparge' because we sparge (spray on hot water, or liquor) through the hops and then also drain this liquor into the fermenter. Hopefully by doing it this way, we have collected up all the remaining wort and imparted lots of lovely hop aromas into the liquor- much better than just shoving in straight liquor. You can aim for a high gravity,meaning you'll have to do a hop sparge which extracts maximum hop flavours for a really aromatic brew.

So that's the hops.

Next is the dilution calculation step which is in theory a way of working out how much liquor to use in a hop sparge to give finished wort at the correct gravity. Although it is an actual calculation, we use a fiddle factor. The fiddle factor (which itself is frequently fiddled) tries to account for the amount of wort left in the pipe work and the hops, as this contains sugar and will contribute to the gravity.

In short, it varies so much between brews that it rarely works first time and often takes a couple of small hop sparges to get the gravity right. If we're really brave we might just cross our fingers and do one big hop sparge after working it out using a big fiddle factor. This is a bit risky though as over sparging means the wort gravity will be lower than intended.

So why is over sparging bad? Well the sugar is needed for fermentation, firstly in the fermenting vessel, and secondly during cask conditioning. To get beer at the right percentage, its essential that enough sugar is fermented during this first stage. We always ferment the beer to the right alcohol content in the fermentation vessel (or as close as we can), but there wont be as much conditioning in the cask because of the lack of remaining sugar. The reduced conditioning doesn't really make a significant difference to the alcohol content, but without this little extra fermentation the beer might be a bit flat. This is because fermentation gives you alcohol and carbon dioxide. The beer will be a little less sweet too, although these are two elements you might not really notice a difference in.

So a majorly over hop sparged beer might give you a flat, less sweet pint. I over hop sparged my special, I hope that's not too flat but I'm going to try it tomorrow and will let you know the verdict.

The sound of beer

'You brew with your ears, not your eyes'.

That was one of my first, and most important lessons from Iain.

All of our brewery vessels, and the connecting pipework, are made of stainless steel. Quite clearly you can't see through this. Unless you're Superman... Everything is moved between the vessels through this network of pipes which are linked and separated by valves. We use a series of stationary and a mobile pumps to do this, so you've got to remember which valves to open and which pump to use.

Effectively, we brew blind and listen for key sounds.

When you first walk into the brewhouse, its noisy. There's the sound of several pumps, the copper burner, cask washer, hammering. Oh and the radio. The sounds which the brewers should be listening for are those which signal the end of a job - like transferring a volume of liquid, but also those of things which aren't quite right, like loose pipe joints or the sound of air being pulled into a pump.

When I started, I couldn't distinguish certain sounds, but I very soon grew used to it. When you give up looking or trying to work it out, the more you can hear - It's best just to give in, even if it feels unnatural.

Anyway, just thought I'd let you know. Carry on.

Also, just watched Pearl Harbour which is a rubbish film. Fact.

The Monster Mash

He did the mash
He did the monster mash
He did the mash...




Well actually a brewer does the 'mash' most days. The degree to which it's a monster depends on many a thing.

Mashing in is the first stage in the brewing process. It's where we blend the ready mixed malted barley and other grains (now called grist) and hot water (we call it liquor) to make a porridgey mixture. This steamy 'mash' is a sweet, satisfying smell close to heaven, particularly on a snowy -6 °C day in Sheffield. When we mash the grist with hot liquor, it has to be at the correct temperature for all the sugars to be released from the grain. This is the basic food for yeast, alcohol being the product of the sugar fermentation. Soaking the grains in hot liquor also releases proteins which make a lot of the beer flavour. After the mash has stood for a little while, we start to run off the liquor with everything dissolved in it - this is called wort, which is turned into our lovely beer.

For the geeks amongst you, the temperature must be 62 - 65°C to activate the right amylase enzyme. This enzyme breaks down the starch stored in the malted barley into fermentable sugar substrates for the yeast. Ideally we need lots of the disaccharide maltose which is produced from the amylase enzymes breaking down amylose. This maltose is fermented by yeast to produce Carbon dioxide and ethanol:

Maltose + Nitrogen (amino acids) + O2 + vitamins and inorganic mols → New yeast cells + ethanol + CO2

So that's the process and science, now for the monster.

Mashing in is done by eye - its where the art and experience come into it. It's important to 'mash in' at the right consistency so that we can get the best possible extract. The rate of hydration (liquor addition) is controlled by a valve which is adjusted by hand. This is important, as a brewer must keep the correct and uniformed consistency when the grist is released from the hopper into the mash tun. Unfortunately, when mashing in during the cold weather all you can see is lots of hot steam and no mash which only leads to what feels like burning your face off, and sneezing like mad. This is an unpleasant, awkward and mildly monsterish characteristic. As my head brewer always says, you've got to use your spider senses and trust your intuition to get it right.

The real monster is the mash tun. This is the big tub which we pour the mash into and leave it to stand, and in a micro brewery we have to dig it out by hand. For a 20 barrel brew (36 gallons per barrel, therefore 720 gallons) it's about 400kg of dry malt, so the weight of spent grains is much more. These spent grains have to be shovelled out of a little door, so a 30 barrel brew length, which is the biggest batch we brew at Kelham, is a bit of a monster to dig.

And it's blinkin' hot. That's another monstery characteristic.

So what happens to the spent grains? It's an awful lot of malt which we can't use again, so a farmer comes to pick it up in big tubs and his cows enjoy it for their dinner. Lovely.

The mash is a bit of monster, but I love it really and without it, there would be no beer.

Skimming over the subject

So at the most simple scientific level, brewing is when sugars from malted grains, mainly barley, are used by yeast to grow giving alcohol as a tasty byproduct. Yeast also makes lots of other stuff in this process which gives beer many of its distinctive flavours. When we brew beer, the healthy yeast sticks together in Carbon dioxide bubbles on the top to make a thick foamy layer.

Fermentation has to be monitored all the time - we want to measure how much of the sugar is turned to alcohol to give your ABV (alcohol by volume, i.e percent!) and this must be consistent. When enough alcohol has been produced, the brewers have to take off as much of the healthy yeast as possible to stop it fermenting too much further. This process is call skimming and it makes my arms hurt an awful lot.

Skimming the yeast usually takes me anywhere between 5 and 30 minutes depending on how much there is - sometimes it's a layer only 3 inches deep, sometimes its over a foot! No matter how long it takes I'm always covered in the stuff, I think yeast must love me a bit. I think its because I sort of lean in to the fermenting vessel to reach it all, although I'm getting better at it now.

This leads me, in rather a tenuous but I think timely manner, to talk about one of the differences between lager and ale styles of beer. The ingredients and processes of making the two styles are quite different, and whist it's a minor factor this does includes our tiny friend - the yeast.

In a very basic explanation, lager is brewed at cold temperatures, a practise originating from cave and underground fermentation processes back in the day. The strain of yeast which thrives at these temperatues, about 10°C, lives at the bottom of the fermenting vessel (ale is at the top, remember?) and it can break down more sugars than ale yeast strains, turning these to alcohol and leaving the lager with less natural sweetness. Ales are fermented at about 18 - 24°C which is optimum for the yeast which floats on the top and ferments fewer of the sugars extracted from the barley.

For all you uber science geeks out there, ale brewers yeast is Saccharomyces cerevisiae while lager yeast is Saccharomyces carlsbergenesis. It is a diploid eukaryote that reproduces by budding which you can see on this lovely artifically coloured electron micograph. Every time yeast is skimmed from the beer we save it in sterile buckets in the fridge (yes, just like the Bosch one at home) and re-pitch this into the next brew. This makes sure that we're always using the same strain to give a consistent product. Breweries sometimes swap their yeast strains to experiment or brew similar recipes.



And here endeth the lesson for today. Any questions, please raise your hand/comment on here.