I have not yet attempted to make my own Kefir but I am planning on it soon so I have no first hand experience to assist I’m afraid.
From the little research I have done it seems that you can use the grains again, up to seven times I believe but that they will look like a collection of gelatinous bits and pieces and I think it only takes about 12-24 hours at room temperature to ferment.
I don’t know whether I’m allowed to post links to other sites but I have lifted this from a site I was reading earlier.
Here are some other tips for making kefir:
- A slightly warmer temperature will speed up the fermentation process, but don’t let them go over 30°C.
- The more kefir grains, the faster the fermentation.
- Refrigerate the kefir milk after removing the grains as it will turn too sour.
- Keep the fermentation out of direct sunlight – UV kills yeast.
- Don’t rinse the grains between batches as this removes the active bacteria on the surface.
The better the quality of milk, the better your kefir. You can use ultra heated milk, full cream or half cream milk, pasteurised or homogenised. We’d rather give our kefir grains (and us!) the full range of nutrients so we feed them the freshest milk (at the moment we are using milk from local farms where we are staying in France) and preferably raw, but if not at least only pasteurised. Lastly, don’t go giving them any of that silly lactose-free milk… the kefir grains won’t have any lactose to consume!
Apparently over-ripened kefir (which increases the sour taste) significantly increases the folic acid content (actually you get different health properties at different stages of the fermentation but you’ll have to research it to understand the others).