- There are two strains of bacteria that you need to have in your starter culture if you want to be able to keep perpetuating and using homemade yogurt as the starter for the next batch: Lactobacillus bulgaricus and Streptococcus thermophilus, (sometimes shortened to L. bulgaricus and S. thermophilus). The Whole Soy & Co. yogurt that I used as my starter contained 4 different bacterial strains, but the two important ones were there, so I have been able to perpetuate and keep making yogurt for a few months now.
- To keep your cultures active and happy, you need to “re-culture” regularly. In other words, you need to make a new batch of yogurt at least every 7-8 or days or so. If you don’t make yogurt this often, you might consider setting aside a couple tablespoons of yogurt from a new batch and freezing it. Although I haven’t tried it myself, I’ve read that freezing starter from freshly made yogurt will allow you to wait about 2 weeks before you need to make another batch.
- Yogurt cultures need sugar! If you make your own soy milk or buy unsweetned soymilk, you should probably add a little sugar to the milk before heating it. Otherwise, the bacteria won’t have much to eat and your yogurt may not culture.
- You can also use another thickener if you don’t want to use cornstarch. Tapioca and arrowroot powder would both work well. You may need to adjust amounts to get the desired thickness.