Can I use Ultra Pasteurized milk? There is nothing else at the store. NEVER EVER use Ultra Pastuerized milk or Flash or UP or UHT or HTST milk. It's cooked, dead milk, and cultures cannot survive in it. Always use milk that states only pasteurized on the label. Also new to the market is ultra-filtered milk, one brand in particular says there is no lactose, which is what your bacteria needs to eat. The fact alone it is overly processed is bad news for a living culture.
I have access to raw milk. Can I use it? Yes, you have two choices. 1) Properly pasteurize the raw milk and continue with the normal directions. 2) If you want to keep the yogurt you consume as raw as possible, you must first do an extra step of making your weekly mother culture with pasteurized raw milk. You can absolutely pasteurize your own raw milk. This allows the yogurt bacteria to take hold in the milk and not be obliterated by the naturally strong raw milk bacteria. Your batches for eating that you make from the pasteurized mother can then be made with raw milk that has not been heated. For more information, please see our post on raw milk yogurt, or contact us here.
Can I use goat milk? You can use just about any animal's milk - cow, sheep, goat, camel, etc, but, it must be regularly pasteurized.
Can I use alternative milk? Eh, yes and no. It's a lot more work and it may not be successful. You'd have to do two batches each week.one to make an actual dairy mother, then a batch of alternative milk yogurt using the dairy mother. This means your batches for consumption will not be vegan or non-dairy, although the amount of dairy is very small. But, oftentimes the alternative milk is so full of additives that the culture has no idea what to do with the milk. It's best to use a Vegan Yogurt Starter (but that has its own set of directions).
How often do I need to make a new batch of yogurt so it will stay alive? You must make new yogurt within 7 days of the last batch (pick a day of the week and stick to it). Yogurt can be made any time before 7 days is up, but 7 days is the longest before the bacteria weakens/dies. It is crucial your mother batch each time is pure, never having been flavored, sweetened, or strained.
But I can make more yogurt from my own strawberry flavored and honey sweetened batch, right? Nope. Repeat, your mother yogurt culture must be what you save before you decide to flavor/sweeten/strain it. It must be plain.
How should I heat the milk? Over low to medium setting, heat the milk slowly so you don't damage the milk. Directly on the stovetop is fine if you keep stirring, or try a double boiler.
What about straining my yogurt? You never HAVE to strain it, only if you want what you'll eat to be thicker, but then say bye-bye to the probiotics of the whey. You can however use whey for soaking your grains or even jump-starting a vegetable ferment. Strain using cheesecloth or butter muslin, or even a commercial yogurt strainer. Remember, you cannot use strained yogurt as your mother culture for your future batch.
How else can I get thicker yogurt? If you want thicker yogurt without damaging the culture, you can slowly heat your milk to 160-180ºF, hold/stir it there for 20-30 minutes, then cool to 110ºF before adding the culture. This damages the cell walls so they coagulate and make for thicker yogurt in the end. You can also use 1 part heavy cream (but not Ultra Pasteurized) to 3 parts whole milk.
What if I want to do more than 1 quart? I have a big family (or appetite)! You can do 2 quarts at a time, just double the starter (not the time). It may be possible to make a larger batch than 2 quarts, but keep a back up mother culture in case the large batch fails.
Should I be careful of metal touching the mother culture? Use silicone or wooden utensils, or 100% stainless steel. Never use another metal as that may kill your culture.
What material should my container be? Culture in glass jars or directly in the IP's steel pot (or crockpot). Plastic is not recommended.
Why did my yogurt turn out lumpy? Your incubation temperature may be too hot, the yogurt cultured too long, or both. The mother culture might also be too old. This batch may not be reculturable.
Why is my yogurt gritty or granular? The milk likely was heated too quickly. Likely this batch is not reculturable.
It tastes bitter! Why? Overculturing is the main culprit. But, if you used too much starter, that can be an issue too, too much bacteria and not enough food. Likely a batch from this batch will also be bitter.
What if I want a more sour yogurt? You have to be careful (keep your back up mother handy), but you can try to make a more sour yogurt by culturing just a tad longer and a tad warmer (but not past 111-112ºF). Remember if you go too long or it's too hot, you can damage the culture. Splitting into curds/whey is a sign it's overcultured.