...and Curious Technophiles
There are elements of the ginger beer recipe that might spawn a few questions if you have brewed your own beer before or are generally knowledgeable about bubbly yeasty things.
The process is similar to beer brewing, but rather truncated to avoid the alcoholic beverage and get something 'soft' instead. In beer brewing, we do a primary fermentation followed by a secondary fermentation then kick-start or 'prime' the final brew as it goes into the bottle to give some desirable carbonation.
The initial work of the yeast is a somewhat 'messy' process in a "primary fermenter." For me that is just a large plastic bucket with enough head-space to allow the big foamy mass to collect on top of the working liquid ("wort") for a few days, then collapse after the bulk of the sugars have been consumed and turned to alcohol by our yeasty animal friends. After that process, discerning beer makers 'rack' (siphon off) the wort into a secondary fermenting vessel - typically a large glass item called a "carboy," which is fitted with an airlock. There, the low-level secondary fermentation continues to consume sugars, while ensuring that wild strains of yeast and other contaminants don't get into your beer. This can last for a week or so after which the yeast has pretty much become dormant.
Beer brewers then rack the liquid off the sediment again in preparation for bottling. The yeast is given a new lease on life by adding a tad more fuel in the form of some malt or glucose or corn sugar as the beer goes into its bottles. After that, the beer sits around for a few weeks to mellow, and when you pop the lid thereafter you not only get the satisfying phhhst, but the beer you pour produces a nice foamy head and is carbonated to your liking.
The grenade effect mentioned earlier is in play here, as you can over-prime the bottles and the yeast can produce so much carbonation as to make them 'splode. Purists won't prime at all, and will rely on the remaining natural fermentation to give you little carbonation without adulteration of the brew. Read about the reinheitsgebot if that gets you all aquiver.
With our ginger beer we are preempting the massive conversion of sugars to alcohol, by arresting the primary fermentation and exploiting it mostly to carbonate our beverage. So, after a brief working period, it is straight into bottles, and we preserve the sweetness which goes so well with the ginger flavour.
Alcohol is still a byproduct of the yeast of course, we're not able to avoid that. But measuring the specific gravity of the pre- and post-brewing product I've calculated that the alcohol by volume is somewhere south of 0.5%, so not likely to get a gnat tipsy.
This shortened brewing process also makes the threat of wild yeasts getting a foothold unlikely. The boiling process starts us off clean, and the vigorous work of our cultivated yeast ensures the competition doesn't have much chance, then it's straight into the refrigerator, so we're protected.
In the casting of the yeast, I'd suggest an extra step for those interested. Rather than directly cast it into the wort, you can re-hydrate it first. The benefit of this is that you give it a bit of a head start, but mostly you can verify that it is viable before committing. Especially if, like me, you're sometimes using old yeast that you've had a bit past its shelf-life. Use a cup of boiled water into which you've dissolved a tablespoon or so of sugar and cooled to 32C in a clean bowl. Again, careful with that temperature! Cast the yeast in, and give it a stir, then let it sit for 10 or 15min. If you look very carefully, (I've even used a magnifying glass) you can verify if the yeast is working by the first little explosions of yeast production bubbling up, as they wake up, eat sugars and make more of themselves.
If you don't see any action after 30min, you probably have dead yeast, so get more rather than risk your batch.
Finally, in the tuning of the flavour, the maximum gingeriness can be gained by paying attention to the sediment in the bottom of your crock-pot after the overnight session. After you strain out all the lumps, those ginger bits still contain a fair bit of bite. You can use a brewing trick here too by rinsing, that is using some boiling water to rinse more flavour out of them. Your beer brewing friends know this as "sparging." Even pressing the bits a little with a spoon as you do so will get the sharp flavour hints out.
Okay, I think I've done the ginger beer to death by now. If you make some, tweet me at @ottaross and let me know how it worked out!
