1. Don’t be overly anxious.
I’ve had readers report sleepless nights in anticipation of a successful batch of yogurt. Getting up to check on your incubating yogurt like it was a sick child with a fever is not really necessary, although I can understand how exciting your first attempt can be.
Resist checking your incubating yogurt every 30 minutes to see if it’s “done” yet. Jostling or moving the bowl may spoil the process. After 5-6 hours it is OK to slightly shake and watch for a gelatin-like jiggle. If a slight shake causes a splash (of the milk, not just the whey sitting on top), apologize for interrupting and excuse yourself for another hour or two while the yogurt bacteria continue to multiply.
NEVER STIR yogurt before it has set.
Also, once you pour it into a strainer or another bowl, it is done incubating. If it didn’t set already, you will have to use as is or try again with more “starter”.
2. Don’t use old milk.
Using it to make yogurt is not a good way to salvage milk on the edge.
3. Don’t incubate yogurt in your oven right after using it to bake dinner.
Doing so can lead to mass murder of yogurt microbes and the sudden cancellation of your yogurt project. You might be surprised how long it takes a 400-degree oven to cool down to 100 degrees.
4. Don’t skip the heating process just because the milk you are using has been pasteurized.
I don’t completely understand the chemistry but heating milk to 175 degrees, pasteurized or otherwise, whether in the microwave or on top of the stove, rearranges the proteins in a way that is beneficial to yogurt bacteria. Skipping this step will result in thinner yogurt more suitable for drinking than straining for Greek yogurt.
5. I know it’s hard to stop, but don’t eat every last drop of your precious homemade yogurt.
Save a tablespoon to use as starter for your next batch. It’s the best (and cheapest) starter there is.
Here is a tip worth the price of this post. Go right now and put a little bit of your freshest homemade yogurt in a small plastic container. Place it in your freezer and save it for a rainy day e.g. the day you forget and accidentally eat the last of your yogurt…or when your spouse or kids unknowingly eat it all …or when you go on vacation ….or when you want to take a break from making yogurt but don’t want to give up the idea forever.
I tried it several times and absolutely could not tell the difference between yogurt made using my own 3-day-old homemade yogurt as starter and that made with my homemade yogurt stored in the freezer for 3 months. I have not done extensive testing to know how LONG one can keep it in the freezer, but it should keep at least 3 months according to my experience.
If you have a precautionary tale gleaned from your own yogurt-making experience, I would love to hear about it.