I've been making kefir for a few months now, and it is going well. I'm not completely convinced that my homemade kefir is quite as soothing to the stomach as the store bought kind, but it doesn't seem to be hurting anybody, and after my initial investment in a case of ball jars, a plastic straining spoon and (of course) a batch of kefir grains, we are presently making quart upon quart of kefir for merely the price of milk.
Basically, all you do is put kefir grains into a ball jar, add milk, cover, and let it sit at room temperature until it turns into kefir. Then you strain out the grains and start a new batch.
There are three factors that affect your kefir processing:
(1) The ratio of kefir grains to milk in your ball jar. They say 1 tablespoon of grains to 1 cup of milk (or 7 oz.) is ideal. If you have scanty grains, it will take longer to turn the milk into kefir. If you have a lot of grains, the process will happen a lot faster.
(2) The temperature in your house. They say that 70-75 degrees is perfect. If your house is warmer than that, the kefir will ferment more quickly. If it is colder, as it was here when the furnace broke (twice), your kefir will ferment more slowly.
(3) The length of time you allow your kefir to culture.
Common advice is to put 1 tablespoons of kefir into 7-8 oz. of milk and let it sit at 72 degrees for 12 hours for mild kefir and 24 hours for strong kefir.
Perhaps because our house is a bit on the chilly side, it seemed to take more time than that for my kefir, especially at first. They warned me that my first batch or two would not be good, and they were oh, so right. Finally for my third batch, I actually added a tablespoon of store-bought kefir to the culture and then let it sit for a full 36 hours. That time I got a usable product (I used the earlier batches too, in pancakes, but they were not drinkable by any stretch of the imagination). I never had to add store bought kefir again, after that one time.
As I continued, the grains began to multiply. Soon I was making two, and then three ball jars of kefir per day. This was fine when everybody was at home over winter break, because we could actually drink it all up (we make smoothies; it is imperative to put the stuff through the blender). After Laura went back to school, Shawn was in Germany, and I was overwhelmed with the amount of kefir I was getting, so I figured out a way to slow it down a little which also saves me a lot of work.
At the beginning, I was culturing the kefir for 24 hours. When it was done, I would strain it, put the strained kefir into a clean ball jar in the refrigerator, and start a new batch on the counter in the old jar. I was washing multitudinous ball jars every day (I even popped the middle knuckle of my right hand because I was forcing my hand through the small mouths of the jars with a cloth to get them thoroughly cleaned), and something had to give...
Since I definitely like my kefir thicker than the kefir I was getting in 12 hours, I learned to follow this trick: I culture the kefir on the counter at room temperature for 12 hours. Then I place the jar in the refrigerator with the grains still in it, just as is, until I am ready to use it. It can stay in the refrigerator like this for a number of days, and it just gets thicker. When I am ready to use it, I strain the kefir directly into the blender using a large, red, circular, plastic skimmer spoon (with the perfect sized holes) that I got at WalMart for (I think) $3.89. I lift the big balls of kefir grains off the spoon, gently shake the excess kefir off them, and put them into a clean ball jar. The rest of the thick stuff left on the spoon, I dump into the blender. This stuff is a mixture of thick kefir curds and tiny kefir grains. The grains are very probiotic, very good for you. I just blend them right into the smoothie along with the frozen fruit, and they are no bother at all.
(1) chilling down the grains routinely and
(2) blending up the tiny grains into our smoothies,
I have controlled the growth of the grains so that they are no longer overwhelming and unmanageable. I also sometimes feed them to our dogs and recently made a special effort to do so when our dogs got diarrhea and needed a cure (it worked, too).
(1) Nothing metal is supposed to come into contact with the grains. This is why I made sure to buy a plastic thing to strain with, and this strainer-spoon has become one of my favorite kitchen tools. I also fold up a square of plastic wrap and put it between the lid of the ball jar and the jar itself while I am culturing the kefir.
(2) You know the kefir has sufficiently cultured when you observe a separation in the jar. The separation may be near the top, in the middle just under the grains, or at the bottom. Usually the longer the kefir cultures, the lower the separation will be in the jar.
(3) Stirring or shaking your kefir will improve the outcome. The kefir is thickest and strongest right around the grains, so if you shake your jar routinely, you spread the cultured parts around and get a slightly smoother, more homogeneous product. Always give it a good, thorough shake right before straining, or most of the best kefir will just cling to the grains and go into the next batch. This won't hurt the next batch any, but you're missing out on the best part of what you made. If you decide to stir, use a plastic spoon.
(4) Keeping your kefir capped fairly tightly will give you a fizzy product. We like it fizzy. This is why we shake rather than stir (see #3 above)... we can keep the lid on when we shake. The lid should be a little bit less than fully tightened so that a little bit of gas can escape. I've read stories about jars exploding, but so far so good over here.
(5) I just use hormone free milk. It is cows' milk and not raw or anything, but I get it at Aldi for $1.75 per gallon and it works.
**(6) I use quite a bit more than 1 tablespoon grains per 7-8 oz. milk. I don't measure, but I would guess that I have between 1/3 and 1/2 cup of kefir grains in each jar. I put the grains in the bottom and then fill the jar with milk to the 3 cup mark on its side.