Back in 2006 while on a permaculture design course in Gippsland, I visited the biodynamic dairy farm of Ron and Bev Smith at Fish Creek. The class was offered a taste of kefir milk and I've never forgotten the taste. Finally this summer I got round to buying kefir grains from Australia's own kefir guru, Dominic Anfiteatro.
Dominic mails out the kefir culture in a small sealed plastic package with milk. The first step is to strain it and put it in fresh milk in a ratio of about 1:7 (kefir:milk) by volume. The lid must be left slightly ajar as the fermentation process produces carbon dioxide.
After 24 hours culturing at room temperature, you strain out the kefir culture and drink the cultured milk. Even though I like the milk, I'm most excited about kefir yoghurt, which Dominc calls kefir-leban, after the middle eastern labneh. So I hung the cultured milk in a piece of cloth (I cut up an old sheet) for 24 hours to drain. And lo and behold, I had labneh.
Its hard to describe the taste of kefir labneh - it is 'peakier' than normal yoghurt or labneh, but that is offset by a unique freshness and texture. Labneh can be made by hanging normal yoghurt as well - I like this stuff better.
One of the most gratifying things about the process is how straightforward it is. You don't need to sterilise equipment, just keep everything reasonably clean, including your hands. This is, in general terms, because the organisms in the starter culture compete so effectively for resources relative to the spoilage organisms.
You can use any type of milk: homogenised and pasteurised, unhomogenised and you can even use low-fat milk or any of the other 'enhanced' milks on the market, although I would recommend you keep it as unprocessed as possible and go for organic and/or biodynamic unhomogenised milk, or if you can get it (lucky you), truly fresh straight from the cow/sheep/goat.
The kefir culture is like sourdough in that it needs to be fed regularly. When you're not culturing a product, you store it in milk in the fridge. If you want to take a break from culturing it, the starter culture apparently lasts in the same milk in the fridge for over a month. As you continue to culture the kefir to make products, it increases in volume, and therefore so does your end product. When you think you have too much for your needs you can store it according to Dom's instructions or give some away to friends.
Like sourdough, kefir culture is a mixture of yeast and bacteria and like sourdough the particular species vary by location. A section on the microbiolog of kefir and lactose digestion is included below.
I've only just scratched the surface of what can be done with kefir labneh. In addition to the herby cream cheese concotion above, I've also put it in a veggie curry as a thickener, added honey to it for a sweet snack, smeared it on sandwiches and toast instead of butter and, my favourite so far, added homemade horseradish (see June 2009 post) to it and served it on steak. Dominic's site includes recipes for all sorts of goodies, including soft and hard cheeses. Think I might try a soft cheese next.
Much of the non-scientific literature about kefir refers to its reputation as suitable for people who have trouble digesting lactose. I did some research on this and found that the scientific literature is clear that lactose digestion is improved from fermented dairy products in general, such as yoghurt, as compared to milk. While it seems clear that kefir is equally as effective as yoghurt in terms of aiding lactose digestion, the evidence for it being better than yoghurt is probably inconclusive.
A microbiological diversion
For those of you with an interest in the microbiology of kefir and lactose digestion, here is the lowdown. An article on kefir in the Journal of the American Dietetic association describes its composition and fermentation action as follows:
"These grains are mass of bacteria, yeasts, polysaccharides, and other products of bacterial metabolism, together with curds of milk protein . . . . Kefir typically has a larger and more diverse range of microorganisms in its starter culture than does yogurt. For example, the kefir used in this study contains the following cultures: Streptococcus lactis, Lactobacillus plantarum, Streptococcus cremoris, Lactobacillus casei, Streptococcus diacetylactis, Saccharomyces florentinus, and Leuconostoc cremoris. The dual fermentation by the lactic acid bacteria and yeasts in kefir results in the production of small amounts of carbon dioxide, alcohol (0.01 to 0.1 g/100 g using starter cultures), and aromatic molecules that give kefir distinctive organoleptic properties compared with yogurt. Kefir typically has a tart flavor, is slightly carbonated because of the naturally occurring carbon dioxide, and is somewhat thicker than milk." (http://dx.doi.org/10.1053/jada.2003.50111)
Lactose digestion is attributed to the activity of the enzyme p-galactosidase which is present in our intestinal mucosa (interestingly, the level of activity of this enzyme varies with ethnic origin). When there is low mucosal P-galactosidase activity, lactose is poorly digested and reaches the final section of the small intestine (the ileum), where it is fermented by the native bacteria there. The volatile end-products of bacterial fermentation of this undigested lactose (i.e. volatile organic acids, carbon dioxide, methane and hydrogen) cause the symptoms of poor lactose digestion.
Lactose digestion is enhanced if it is consumed together with fermented milk products such as yoghurt. This enhancement is attributed to the presence of β-galactosidase in the starter culture bacteria for yoghurt, particularly the lactobacilli species (lactobacilli are bacteria that convert sugars, including lactose, to lactic acid). Because yogurt has good buffering capacity, it allows some of the bacterial cells to survive the gastric acid in the stomach and reach the first section of the small intestine (the duodenum) intact. At that point, it is thought that bile acids play a role, either by causing the breakdown (lysis) of the bacterial cells, thereby releasing β-galactosidase or by altering of the permeability of the cell membrane so that lactose can easily enter into the cell. Whatever the mechanism, the β-galactosidase gains access to the lactose substrate. Thus yoghurt is said to have an "autodigestive capacity".