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Tuesday, July 11, 2006

The Great Ginger Beer Experiment

1.1kg ginger

I have been in Australia a year now and it is high time I began brewing again. Aussie beer isn’t that great and I’m missing a decent pint of bitter. Thankfully the Aussies are quite interested in home-brewing so 15 minutes with Google and I’d found a homebrew shop 5 minutes drive from where I work. $130 later and I have enough equipment and consumables to keep me happy for several months. Before I start to brew proper beer that tastes of something however I have unfinished business with Ginger Beer.

I have been trying to brew drinkable ginger beer since I was a child. The first abortive attempt was based on a recipe from the Food and Drink programme on BBC 2 in the 1980s. The presenters cooed and clucked over what was clearly a new idea to them. Egged on by their impressed pouting faces as they exclaimed how much better it was than the over-sweet and not gingery enough shop-bought ginger beer we boiled up our ingredients, bottled them with the right amount of yeast and left the bottles in the cellar to ferment until ready to drink. I religiously checked the bottles for a week to see if they were ready to drink always drawing a blank. Then one Sunday evening we were sat back in post-dinner post-muppet show reverie when we interrupted by a loud POP from the cellar. The bottles were either blowing off their lids or simply exploding. I was so surprised I nearly soiled my pyjamas.

The problem with ginger beer is that you need a great deal of sugar to keep it sweet. But the yeast you use to brew it consumes sugar and turns it into alcohol and CO2. If you give yeast a super-abundance of food it just keeps going until it runs out, or its’ own by-products kill it off. Yeast won’t tolerate alcohol much above 10% by volume but it is much less sensitive to CO2 and much more efficient in producing it. Thus ginger beer is much more difficult to brew than ordinary beer. In ordinary beer you don’t want any sugar left in the brewing process all the sugar turns to alcohol and you are left with the flavour of malt and hops. In bottle and cask conditioned traditional beer a small amount of priming sugar is added to the bottle or to the barrel to achieve the fizz. The mass produced beers that you buy in cans or bottles are actually brewed until flat, filtered, pasteurised and then artificially force carbonated in the same way that soft-drinks are. In Ginger beer you need sugar left in the mixture to keep a little sweetness or you end up with a very dry ginger ale.

This leaves the home ginger-beer brewer with a few problems. Pasteurisation to stop fermentation and force carbonation isn’t really an option because of the amount of kit needed. Teenage over-enthusiasm aside neither is producing a special-brew strength ginger beer, although from the research I’ve done the final strength of the original brew was around 11%. You just don’t need that much alcohol in it so a way to keep it fizzy but keep the alcohol levels down must be found. The way this seems to have been tackled in the late Victorian era was to maintain a steady fermentation in a jug, pouring off the product into a bottle to finish the fermentation/carbonation and serving the brew with the yeast still very much alive in it. This is how I approached a much later adulthood attempt at ginger beer.

Still using baker’s yeast to emphasize CO2 production and not alcohol I started a jug of warm water, sugar, ground ginger and yeast. You feed it a spoonful of sugar and a spoonful of ginger everyday for a week then pour off the fermenting mixture into a bottle, leave that for a few days then open and enjoy, or not, in fact decidedly not. The same sort of mixture results; very yeasty dusty and a bit gingery. Not pleasant at all. I did some research and discovered that there is actually a second microbe in the closest recipe you can get to the original and that this is normally available only from “yeast banks”. At this point I give up.

Ginger beer is very popular in Australia which has several different brands available in just about every corner store. Some of the breweries still produce ginger beers to original recipes. So why am I bothering to make my own? Because I’m a stubborn bastard and if you don’t learn to do something better when you fail at it you may as well not have tried in the first place. I want superior ginger beer with proper flavour and a bit of an alcoholic kick to it and I am not going to be discouraged by the thought that I can buy a bottle of ginger beer and add vodka to it. That seems just a little too easy.

A little problem solving needs to be used in constructing a recipe as not once have I succeeded in brewing anything gingery and drinkable whereas my ordinary beer results have been excellent. The main problems are flavour, alcohol, and pressure and they are all closely related.

There are two problems with the flavour; yeast and a dusty ginger taste. The dusty ginger taste seems to come from using ground ginger and in the case of the experiment using the jug to ferment the mixture, not cooking it. Fresh ginger is clearly the way forward. The older recipes also include a fair amount of lemon juice so that will be going in too. To make the taste a bit richer and smoother a vanilla pod will also go in and a tiny bit of cinnamon.

The yeast is down to a couple of things, firstly I have mostly been using baker’s yeast which has very different properties to brewing yeast and secondly the huge quantity of sugar in the mixture keeps almost all the yeast alive and in suspension in the final product. This time I will use brewing yeast but I will have to find a way of sweetening the mixture. Lactose is the answer. Lactose is the sugar in milk and because it is derived from an animal source the yeast I’m using can’t ferment it, I have my sweetener but I won’t be inviting any vegans to try my ginger beer (not that I would anyway, scrounging bloody hippies!).

I still want some alcohol in my final ginger beer but I don’t want knockout drops. This can be quite a big risk with home brewed beer as you can’t “feel” the alcohol like you can in commercial beer. You can keep additives to homebrew to an absolute minimum and you are fermenting the beer at almost optimum temperature so the alcohol is of only a single type and is extremely clean. This makes it tempting to bung in loads of sugar and make extremely strong beer. However if you add too much sugar you can corrupt the flavour and start producing different alcohol and nasty acids. I am also using brewing yeast which responds differently to different sugars.

The brewing yeast I’m using has evolved to brew maltose. Maltose is a fairly simple disaccharide sugar which in brewing is traditionally derived from roasting germinated grain. It is easily broken into two glucose molecules by yeast, glucose is an almost universal metabolic sugar and can be thought of as the most basic carbohydrate. Maltose added in the form of malt also carries additional flavour. Disaccharides like maltose provide a slower, steady and stable fermentation with no tainting from by-products of breaking more complex sugars like sucrose down into metabolic sugars. Because I also want the fermentation to get off to a vigorous start I’ll need a metabolic sugar to get things going, dextrose or glucose are the normal brewers’ choices. I’ve found a “beer improver” sugar pack which contains spraymalt, dextrose and glucose – perfect.

The bursting bottles incident shows that yeast is quite capable of producing enough pressure to cause problems. For every molecule of glucose broken down, two CO2 molecules are produced. Meaning that for every molecule of maltose there will be four CO2 molecules. CO2 has some fairly alarming properties not the least of which is that its’ solid form is a quarter the size of its gaseous form (it also has no liquid phase which is a bit strange in itself). The net result of this is that the product of fermentation is a lot larger in volume than the starting ingredients. The reason that beer doesn’t blow up its’ bottles is that, even in the live brews that I make, the beer is fermented until it all but stops and when the yeast falls out of suspension the brew is syphoned into bottles and a very small amount of priming sugar added (approx 1 tsp. sugar per litre). As I don’t need to keep fermentable sugar in the mixture to make the brew sweet, this is how I shall approach my ginger beer too.

Now I need to do a bit of maths to work out my quantities for the recipe and I will need to do this on a litre volume so that I can multiply it back up to suit. I would normally use approx. 3kg of malt syrup to make 23l of beer. If I assume that all of that is fermentable sugar I need 43.5g of fermentable sugar per litre to get an alcoholic brew of about the same strength (4.5 – 5% a.b.v.).
How sweet do I want the final brew? Sweet enough to be pleasant, but not so sweet that it becomes sickly. Sweet soft drinks like Coca Cola have up to 17tsp sugar per can in them and they are far too sweet. A can of soda is 330ml and a tsp of sugar is 4 grams so a litre of soda would have about 200g of sugar in it – I probably want about half of this amount so I need maybe a little over 100g of lactose per litre.

How much ginger do I need? The sensible person would probably have looked at the back of a ginger beer bottle at this point, consulted a few recipe books and made a very educated guess. I went shopping and bought as much ginger as I thought looked right, 1.1kg of root ginger. Splendid.

Let’s multiply it all back up to get final amounts. I have 12 750ml bottles at hand so that’s 9 litres, ergo I need:

390-400g fermentable sugar
900g Lactose
This works out at 120g of root ginger per litre or a little over 91g per bottle. This is when it began to dawn on me that perhaps I had over bought on the ginger. Never mind, get it on the stove see how it tastes.

1.1kg ginger puree

I peeled the ginger and zapped it in a blender with the juice of 3 lemons, added my vanilla pod, about half a teaspoonful of cinnamon and a few litres of water and brought this mixture to a boil and simmer. This is to serve a couple of ends; the vanilla needs to be infused into the mixture, the ginger needs to be cooked through and I’ve got a lot of sugar to get into not very much water so it will have to be hot. In went the lactose, and the fermentable sugar. On tasting the mixture the first thing that jumped to mind was that I seemed to have made several litres of fantastic cough syrup, which looks like lumpy custard. I also realised that this is going to be very gingery ginger beer indeed. Over exuberance has got the better of me and I will have to increase the volume and not worry too much about the rest of the measurements. I’m also going to need a few more bottles.

In went the remaining 100g of Lactose and a fair bit more of the fermentable sugar. The final brew isn’t going to be very sweet but it will be very gingery and it will be fairly alcoholic. I put the heated mixture in the fermenter and added enough cold water to make it merely warm, about another 7litres bringing it to way over the target volume. I revived a bit of the yeast with some warm water and sugar in a jug which means it will start more quickly and won’t suffer “cold shock” when I put it in the mixture. The fermenter goes into the cupboard under the stairs and I have to wait until the mixture stops bubbling and the yeast begins to die back a little before bottling. Given the amount of fermentable sugar now in the brew that could take well over a fortnight.

What I’m going to end up with is a strong sweet-ish ginger ale that will probably be clear amber in colour rather than cloudy and pale. I’m not actually sure how much I’ve made, as I had to add ice to the mixture too, to bring the temperature down to tolerable for the yeast. Dead reckoning and experience suggests I’ve made about 11litres – given the amount of sediment that all the pureed ginger will leave I reckon I’m not too far off the mark. I tried to take a hydrometer reading but the hydrometer I bought didn’t come with a sample jar, so I can’t even tell you how strong the brew will be, curses.

A week on and the bubbling hasn’t stopped but the under-stairs cupboard smells fantastic!

Updates as they happen.