Saturday, September 26, 2009

Sugar in brewing.

Recently there's been an interesting post by Ronald Pattison (xtreme beer-history buff) on use of "sugar" in brewing. In the comments following it's become apparent that some people hold very strong views on the subject. It's looking like one of those religious issues. It also seems that some people are quite confused about the whole thing.

Nowadays we use sucrose or invert sugar in brewing not so much for economy, but rather to allow us to control the fermentability of our worts. To understand how this works, it's important to be aware of the difference between what's commonly called sugar (sucrose) and sugars generally. It might be better to talk about carbohydrates really, but I'm comfortable with sugars v. sugar , so try to keep up. Wort carbohydrates include the monosaccharides fructose & glucose, the disaccharides sucrose & maltose, maltotriose (a trisaccharide), and more complex sugars (often called dextrins). Our yeast can only eat fairly simple sugars - the 'mono' and 'di' saccharides and some others.

A typical British Pale Ale wort with an original gravity (OG) of 1040 might contain a little more than 9 grams of sugar per 100 millilitres, of which less than 7g will be fermentable (including 0.5g sucrose - table sugar). This leaves something like 2g / 100ml of the higher sugars to contribute to taste and body in the finished beer and final gravity (FG) of around 1008.

Broadly, we can say that a beer with high levels of unfermented sugars will be sweeter, with more body than a beer with relatively low levels of these dextrins. But of course, we don't always want sweet beers with lots of body. Indeed, Belgian brewers speak of the digestibility of their beers, by which I guess they mean the relatively light body (considering the alcoholic strength) of many of their offerings. Digestible beers don't fill you up. A relatively light body, with dryness are also characteristics of some British beers, it's part of what makes our session beers so sessionable - so how do we go about achieving this?

To a certain extent we can control the fermentability of the wort by controlling mash temperature. The various enzymes in the malt have different optimum temperatures for their actions. So a little bit warmer (say 67C) might give us a less fermentable wort (lower proportion of fermentable sugars), while a bit cooler (64C) might give us a more fermentable wort leading to a drier (thinner) finished beer.

We can also make a difference by our choice of yeast. Yeast tends to consume sugars in sequence. It's like a child eating the chips first, then the sausage, followed by the beans. So the simpler sugars are utilised first, the more complex ones (which require the mobilisation of more yeast cell machinery) only when the easy stuff is used up. A yeast that's highly flocculent, i.e. falls out of suspension quickly, will tend to leave a higher proportion of the more complex sugars unfermented, even though it has the right machinery. A less flocculent yeast might produce a drier beer, by hanging around for long enough to have a good go at all the fermentables. Some yeasts are constitutionally unable to use maltotriose - they just don't have the tools for the job.

We can control the fermentable / unfermentable balance of the wort by directly adding fermentable sugars while keeping the OG the same (i.e. reducing the amount of malt somewhat). We can chose to add mainly simple sugars, a useful technique allowing us to use more flocculent yeasts (good for producing clear beers in a short time with simple equipment), without leaving too much unfermented at this stage.

This is the basis for brewers adding invert sugar to their wort. Invert sugar is sucrose (table sugar) which has been treated to break it down into glucose and fructose. This is often done by heating an acidified solution of sucrose. It's Quite Interesting to note that as the hydrolysis proceeds, the optical properties of the solution change, with more fully hydrolysed solutions rotating polarised light in the opposite direction to a sucrose solution - which is why we call it invert sugar...

The fermentability of commercially available invert sugars seems to be in the range 94% - 99%, although some of the really dark ones, which will have more unfermentable stuff in them, will be less fermentable (90% or so). Other, starch derived products can be got with more or less whatever fermentability you want, and are commonly used as brew-length extenders (which is a good way of saying profit enhancers).

Anyway, throwing good old sucrose into the boil works well (although you'd be advised to make a solution / syrup up first unless you particularly want to be chipping burnt toffee of your elements all the next day). In the acid conditions of the boiling wort a proportion of the sucrose is hydrolysed for you. I should think.

Friday, September 18, 2009

That time of year again.

In Ulverston (where we are) there's a sort-of dress-up weekend during which the out-going types are encouraged to wear clothes harking back to the 1850's (approximately). Given that we aren't really dressing up kind of people, our contribution to the Dickensian Festival is a strong ale (6.5%) called (as a nod to Dickens) "Genuine Stunning", and that's what we're making today. Last year, we didn't sell any to anyone in time for the festival, but at least we knew.

There's a free pint for the first person to spot the secret ingredient. But you'll have to wait until November before we let it out.

Tuesday, September 15, 2009

A Modern Porter...

... is what we're brewing today.

There's an awful lot of guff stuff written about porters. The point's been made (elsewhere, at length), that they're historically interesting - blah... blah... the first truly industrial British beer. Early porters were great, later ones - mass produced bastardisations of the lovely brown beers that pre-dated them. Blah. But we're not a historical reconstruction society (there are family members who were in Ye Sealed Knot so we've a real feel for the hideous awfulness of that phrase), hence we'll be making a modern porter called (confusingly perhaps) "Revival Porter".

There's a lot of really good beers out there called "porter", it's a very broad church nowadays. Good.

Ours should be: On the brown side of black, about 4.7%, slightly sweet with a fruity chocolate aroma, moderate bitterness and a dryish finish. Or something. Anyway, it's in the fermenter now, and I've chucked in some yeast.

Good news: The new pumps for the cooler arrived! We got two, so now there's a spare. Of course, something else will go next.

Saturday, September 12, 2009

That beer's so last month.

Brewers usually put a best before date on containers as they go out of the place. It's pretty usual to only consider requests for returns (ullage and that) for stuff before the best before date. It's also usual for retailers to require a sensible amount of time in which to get around to selling the beer - 22 days would be a typical request. Wholesalers might want a month.

In effect the brewers are warranting that the beer is going to be OK up to the date, but anything might happen after that (explode, go sour, taste of goats, etc) for which they won't be held responsible. Some beers will keep for ages: Strong beers, dark beers, and particularly strong dark beers. All live beer will change as it ages, and for some beers this will be a good thing, for others a bad thing. We condition our weaker beers for at least a week before they go out, so they'll be fit to drink as soon as they're vented and drop bright. We'd normally suggest that they're drunk within a couple of weeks after they get to the pub - these are beers meant to be enjoyed while they're fresh. As they become aged the lower alcohol pale beers can tend to dull a bit, still good - but not as good.

The bad news for the day is that the recirculating pump on the big chiller has packed up and that we don't have a spare. Let's see if we can get a new one by tuesday, otherwise we'll have trouble cooling down the fermenter full of Golden.

Tuesday, September 01, 2009

Normal service resumed.

Well, pretty much. We did some Best Bitter tuesday, and today we're doing the West Coast Blond. "Oooh", you might say, "Push the envelope why don't you". It's beer we need - to sell - the stock is looking a bit depleted. We had our "production meeting" and have pencilled in something (well 3 things) more experimental for the rest of the month, about which more later.

Jeff Pickthall came to see us today, so Becky had to prove she can brew while I chatted. Very relaxing it was, and of course (in spite of her tiny hangover), everything went fine. While talking, I was reminded of visiting herself when she was working in Belgium. Now that's a place where it's just about impossible to get truly bad beer. Apart from all the super-lovely beers that everyone goes on about, even their cooking lager makes our cooking lager look stupid. The Stella is actually quite nice and Jupiter Jupiler (which seemed to me what most Belgians actually drank most of) takes Carling outside, beats it up and steals its girlfriend.

P.S. I'm adding this (7.9.09) to admit that I haven't been to mainland Europe (except to change planes) since 1995 - so I don't really know what I'm talking about anymore (if I ever did).