Mesophils
Those of you ordering mesophils need to know that in most cases, your yogurts will be thinner than your thermophils. Using UHT milk, I’ve noticed, negates a lot of this issue and results in thicker mesos.
If it’s happened to you that your mesophil is really runny, the first thing you need to do is make sure you didn’t order a drinking yogurt. There are a lot of them in the mesophil category. If you did order a drinking yogurt, you’ve got two options here.
Option #1: revel in the new experience and enjoy your drinking yogurt!
Option #2: monkey with it.
If you are going to monkey with your yogurt, take a sample of the third batch and tuck it in the freezer in case you break it. It happens sometimes that you break them while doing experiments. I like breast milk bags for this, since they rarely leak and are designed for freezing dairy. Target makes the best ones, in my experience (Up&Up brand), but they all generally get the job done.
Generally what I do with a drinking yogurt I’d like to see become a spoonable yogurt is double the amount of culture I’m adding. I do this only until I’ve talked the yogurt into forgetting who it really is and believing it can be a spooning yogurt, then I use the regular ratio again. I’ve never personally had one revert to a drinking yogurt without reversing that process (using half of the regular amount of culture for the next batch), but I’ve heard of it happening.
Be aware that doubling the amount of culture can do weird and sometimes unpleasant things to the texture. Give it 3 batches per experiment, because you’re really “reactivating” the culture according to the off-book standards you’ve decided it should conform to, so offer some patience.
Thermophils
In my experience, if this is still going on after the 3rd batch for someone in our community, it’s a heat issue. A lot of people seem to favor insanely hot milk, up to 120F. I don’t really understand this, because it weakens the culture in some dramatic ways. Me personally? I like 90F for longer time. It gives a more complex flavor profile and very thick yogurt without the need to strain. I personally am not inclined to go over 100F to culture my yogurts, no matter what method I’m using. Ideally, you’ll cap this at 110F. You can go higher, and there are a few niche yogurts that do like higher temps than 110F, but mostly not so much.
The only other reason I ever see post-activation runny thermos is because the person waited a long time to do their next batch. Don’t leave it in the fridge for weeks on end, y’all, without freezing some or reculturing.
Okay, okay. You’re right. I totally do this too, and I don’t lie about it. But if you did it and it didn’t pan, you are basically stuck restrengthening your culture (read as: activation batches again). So freeze or reculture every 7 days. I have a jar with at least a full cup of yogurt in my freezer because I know Child Tester wants to eat it, but she definitely doesn’t want to eat it right now. It’ll be runny when it thaws (smoothies, mashed potatoes, or baked goods to use the excess), but it will reculture the next batch perfectly!
Final Words
To recap, in nearly every instance, a culture can be saved. Please let us help you if you’ve done the three activation batches and your yogurt is still misbehaving. We are good at saving cultures, and are committed to you having a positive experience in saving some money and gaining independence by making your own yogurts!