Yogurt Is Low Tech and Easier Than You Think.

I eat more yogurt than anyone I know. Maybe 2 or 3 per day and I don't get tired of it. If you add to that the Kefir I drink that would bring me way above the average. You may think that I eat so much because of some fad yogurt diet or all the talk about probiotics and how good they for you, but that's not the case. I just love the stuff!
Yogurt can have various textures from light to very heavy and creamy like Greek style. Greek style yogurt is more or less a strained yogurt that is actually very thick. A lot of the liquid is drained off leaving you with something that's thicker than sour cream. I am a big fan of the sweet kind with fruit on the bottom, since that's what I grew up on, but I also really like making dips and dressings or marinades with it as well. Yogurt makes a great marinade when it's mixed with herbs or curry for things like lamb or chicken. When it's grilled it caramelizes and makes sort of a crust on the surface.
The other day as I was thinking of another way of making an everyday item I would normally buy at the store, I thought I'd try to make yogurt in the most low-tech way as possible. Armed with only two 6 oz yogurts and a gallon of raw milk I thought I'd give it a go. After a little research on finding the prime temperature range for culture growth I then stumbled upon the one of the coolest ways of incubating without any extraordinary equipment. I took a large IGLOO cooler from the basement and washed it out just to make sure I was working clean. I was gonna use the "cooler" as a "warmer" instead. The insulation works perfectly to hold the necessary temperature of the milk while the cultures are working. The process takes about 6-7 hours.(Don't quote me on that length of time, you should see for yourself. I left the yogurt to set while I went to work.) The one essential part of which I read in the book "On Food and Cooking" by Harold McGee was the heating of the milk. His description of it is that "the milk can be heated to 185F for 30 minutes or 195F for 10 minutes". "Th[is] treatment improves the consistency of the yogurt by denaturing the whey protein lactoglobulin, whose otherwise nonreactive molecules then participate by clustering on the surface of the casein particles. With the helpful interference of the lactoglobulins, the casein particles can only bond to each other in a few spots, and so gather not in clusters but in fine matrix of chains that is much better at retaining liquid in its small interstices." Here is this link to read on yourself: http://books.google.com/books?id=oWqlY5vEafIC&lpg=PP1&dq=harold%20mcgee%20on%20food%20and%20cooking&pg=PA48#v=onepage&q=&f=true
This heat treatment will give you a smooth texture to your yogurt. If you want an even thicker yogurt you can add some dry milk powder to increase the protein and make it more dense.

So just to give you the correct procedure, I'll start from the beginning...

Procedure:

1 Gallon of Milk (unpasteurized)
2 (6 oz) containers of plain yogurt (With Live and Active cultures. This you can read on the side of the container)
1 gallon Pot
1 large Insulated Cooler
A Thermometer that read up to 212F
Containers you want to fill with yogurt and covers.

1. Open the 2 yogurts and them with whisk 2 cups of the milk
2. Pour the rest of the milk into the pot and set it onto a medium high burner to warm. Heat milk up to 195F, hold it for 10 minutes and then remove it. To prevent the milk from scorching on the bottom of the pan, whisk it very frequently and
3. Thoroughly cool the milk down to 125F.
4. When it's ready, add the yogurt and milk mixture and whisk it well.
5. Get hot water from your tap (about 135F will do) and pour it into the cooler.
6. Pour your milk mixture into your container and cover.
7. Set your containers into the cooler with the warm water being sure the water does not come too close to the lids. If so take out some of the water.
8. Close the lid and let it ferment until the yogurt is set. About 6-7 hours.

That is really all you have to do. You can make all the yogurt you want just by buying a couple extra plain ones when you shop! After you make your first one you can continue to make more as long as you save 2 cups of your last batch. Yogurt can get expensive, costing $5.00 for 4 6-oz containers, if it's not on sale. You can make a ton more for that much and choose what goes into it. Save some of your money by making your own yogurt so you can spend it on other things that you can't make yourself.