Water kefir

For most of my childhood, my parents carefully followed conventional health advice. That meant whole grains and low fat - though since most of what fat there was, was vegetable margarine, that may have been a blessing of sorts. However, on the plus side, it also meant sweets and soda pop were strictly rationed. Pop was very much a treat, a few times a year, and evokes happy memories of hot summer holiday afternoons.

Of course, these days I drink regular pop practically never. Apart from the myriad health concerns, it just tastes absurdly and unpalatably sweet. But, especially in the summer, I drink water kefir, aka tibicos, on a daily basis. For those who haven't tried it, it's a kind of fizzy homebrew probiotic pop, made basically from a sugar solution fermented with water kefir grains - little slippery, translucent, self-propogating crystals. The process is actually very simple, once you get the hang of it. About ten minutes every few days keeps us supplied. It's also a great source of probiotics, being fermented by a colony of bacteria and yeasts.

What I mostly make is ginger beer. I use a mason jar that holds about 3 litres, and e-z cap beer bottles. It's a 2-stage process. First I whizz up a largish chunk of raw ginger in the blender with water. Then I strain it into the big jar with a sieve (the leftover ginger mush I use up for cooking). Along with this goes about an ounce or so of sugar. Any old sugar will do, though I tend to use jaggery or light muscovado if I've got it; the flavour is stronger and you get a few extra minerals. Half a lemon, or lime, or an orange, unsqueezed. And the grains (you can get these easily online). Top up to the brim, and leave for about 24 hours.

Pretty quickly the fermentation becomes apparent. There's a constant bubbling and sometimes the grains will float up and down in the jar, which is quite entertaining to watch if there's nothing on TV.

Then comes the bottling. The easiest way I've arrived at to do this is to fish out the lemon, squeeze it into a large jug, and then pour the rest of the brew into the jug through a sieve (to retrieve the grains). Then pour into the bottles, seal and leave out for another 24-48 hours. After that they should be stored in the fridge or somewhere cold, or they'll carry on fermenting and either burst a gasket or turn vinegary.

Depending on how much sugar you use in the first place, and how long it ferments, this formula ends up something like a sparkling, very dry, ginger ale. Not sweet and with a complex, slightly beery flavour; in fact, it also goes some way to making up for the lack of beer on a gluten free diet. I make a batch one or two times a week. Between batches, the grains sit in sugar water in a much smaller glass jar in the fridge.

That's the ginger beer version. You can make all sorts of varieties. Fruit brews are particularly good - complex, fruity and winey; I made one with wild blackberries that was absolutely ambrosial, like a beaker of the warm south. White grape juice makes something like champagne, and apple juice a dry cider. In this case, though, it's better to keep the fruit element apart from the grains. Just add a bottle of finished kefir, or some sugar water from the resting grains in the fridge, to the juiced fruit and then proceed as before.

Safety note: when I first started making water kefir, I read all sorts of dire warnings about exploding bottles. I've never had a problem yet, but it's certainly possible if the fermentation allows too much gas to build up - if you use a lot of sugar and leave the stuff out for too long. This sounds scary, but with common sense you shouldn't have a problem. My initial fermentation jar doesn't have a completely airtight lid, so that lets excess pressure escape at that stage. Failing that you could cover the jar, or jug, with cloth or kitchen paper and a rubber band just to keep the dust and flies out. For the second stage - the bottle conditioning - you can use plastic pop or water bottles. Beer bottles are designed to withstand some pressure, though. If you're making something about as fizzy as beer, you'll be fine. And you pretty soon get to know how fizzy the brew gets, and how soon. A good thing to do is, at least for the first few batches, to open the cap once or twice a day to see how the pressure is building. A huge gust as you open it and you know there's a lot of pressure. It's also as well to try this over a sink, as occasionally you might get a geyser fountaining out. In my experience though, this only happens with very fruity beverages.

Safety note no.2: some alcohol will be generated. I've seen estimates ranging from 0-2%. Personally, I'd guess from the taste and lack of intoxicating effects that it's on the lower end of that. Perfectly ok to give children, in my opinion, though to be absolutely safe you might want to avoid quaffing literally pints of the stuff before getting behind the wheel. Of course, you might want a more alcoholic brew, in which case you could try upping the sugar content and going for a longer fermentation. (You could also experiment with adding hops, I suppose. Traditionally these were used in beer for their antibacterial action - suppressing the bacterial growth in favour of the yeast, the yeast being the more potent alcohol-creators.) Be warned, though - letting the mixture get too alcoholic in the initial stage when the grains are still present could well pickle and kill them. Better confine the alcohol pursuit to the second stage, and bear in mind the need for caution with pressure build-up, as above.