Yogurt, by definition, is a dairy product. However, with the need to provide non-dairy equivalents to dairy products, yogurt makers struggled with various formulae to make yogurt from soy, coconut milk and so forth.
The problem, of course, is that yogurt is made from specific bacteria which thrive on the lactose which is found in dairy but not in non-dairy products. The challenge is to either find different bacteria and/or trick existing bacteria into culturing non-dairy products.
Is this hard to do? Well we have struggled for many months to try to culture soy "milk" (milk is a term reserved for dairy products) but with little success. Although there are many recipes and ideas floating around the Web, until we discovered that soy protein should be added to instant soy powder with sugar, our soy yogurt turned out thin without any favorable taste at all.
Here is the recipe:
2 quarts water
2 cups instant soy
8 scoops soy protein
4 tbs sugar
1 tsp salt
2 tbsp corn starch
2 tsp lemon extract
1 tbsp vanilla extract.
You can mix it all together and boil it until no more foam rises on top. This is important because there are certain enzymes in soy which can counteract certain medications which you may be taking.
Then we cooled, cultured it and put it in our yogurt maker for 8 hours and it was the firmest yet we have made. The taste was considerably better than any we had made in the past.
We believe that using flavorings will enhance the taste of soy yogurt - and have heard that, for example, strawberry flavoring does mask the strong soy taste.