How to make yogurt

A friend didn’t know it’s easy to make yogurt at home (or that it’s possible at all). There’s not much to it, really, and it only takes a few hours from start to finish. This is lightning quick in Fermentation Land, where normally finished products take weeks, months, or even years to create.

The lovely thing about making yogurt at home is that it doesn’t really need any special gear. Anyone who tells you it requires a special yogurt maker, InstaPot, or any other such nonsense is just looking for a payout. People have been making yogurt for thousands of years, and they didn’t need a special kitchen appliance to do it.

The basic process is to add a starter to warm milk, then give it a warm place to ferment for a few hours, then you have yogurt. That’s it, but here are the specifics:

Hardware

• A pot with a well-fitting lid
• An instant read thermometer (a’la a Thermapen)
• A whisk
• A warm place where the milk can ferment overnight (see the Ferment step below)
• Something to strain the yogurt (optional, but you’ll probably want to do this); some potential options…
  • A collander lined with cheesecloth or a clean kitchen towel, or
  • A jelly strainer, nut milk bag, or other special tool, and
  • A large bowl for catching the strained whey
• Something for storing the finished yogurt (I use a lidded, plastic Rubbermaid container)

Ingredients

• 1 or 2 litres of 2% or lowfat milk
• A couple tablespoons of yogurt starter, which is either…
  • from a previous batch of yogurt, or
  • from a cup of plain, store-bought yogurt if you’re just starting out or don’t have a previous batch

Method

Prepare the milk

1. Pour the milk into the pot and slowly bring it up to 180°F/82°C. Stir frequently to keep the milk from sticking to the bottom of the pan as it heats. Do not let it boil. This step not only prepares the milk proteins for fermentation, it also would kill off any bacteria that might compete with the happy little lactobacilli you’ll add from the starter.
2. Take the pot off the heat and allow it to cool down to between 80-100°F (27-38°C). Hotter than this and you risk killing the bacteria in the starter. Cooler and the bacteria won’t do their thing very quickly (or perhaps at all).
3. Whisk the starter into the warm milk.
4. Put the top on the pot and move to the Ferment step.

Ferment

1. Set the covered pot in the warm place for about 8 hours.

Yes, that’s the only step here, but that “warm place” needs some explanation…

Basically, the starter has innoculated the milk with lactobacilli bacteria. They’ll process the lactose in the milk into lactic acid, which then acts on the milk proteins to create the creamy structure of yogurt.

These bacteria need time and warmth to do their thing. Time is easy: prep the milk before you go to bed and the yogurt will be ready in the morning. Warmth, though? There are two low-stress ways to manage this:

• If you have a gas oven that has a pilot light, pop the pot into the oven, close the door, walk away.
• No gas oven? Get an electric heating pad and a blanket. Open up the blanket, place the heating pad on it, then put the pot on the heating pad, and cover everything up with the rest of the blanket. Turn the heating pad onto its lowest setting, then walk away. This is my “warm place” of choice for my yogurt and it works like a charm.

Nota Bene: The time is flexible. If you forget about it and don’t check on your yogurt until later in the day? No problem! Remember, yogurt is a way to preserve milk, so it’ll still absolutely be safe to eat.

Strain and store

The expensive Greek yogurt you see in the store is simply regular yogurt that’s been strained to remove a lot of the whey. Whey is the liquid that you’ll sometimes find pooled in your yogurt after you take a scoop of it then let it set for a while. There’s nothing wrong with whey, but you’ll find that your homemade yogurt will “leak” whey a lot more than anything you get from the store. That’s because theirs have a lot of stabilisers in there like gelatine and what have you. Yours does not.

To strain your yogurt, place your straining device (towel-lined collander, jelly bag, etc) over a large bowl, add your yogurt to the strainer, then walk away.

Check back from time to time to make sure the whey doesn’t overflow the bowl or reach the level of the straining device. I also like to mix up the yogurt at these times. Otherwise the part of the yogurt closest to the strainer gets more strained than the interior of the mass of yogurt. Mixing helps things strain more evenly.

When the yogurt has reached a consistency you prefer, pop it into something large enough to hold it all then refrigerate it. It’ll last as long as you need it to, as long as it doesn’t start to grow mold. While the bacteria prefer warmth, they’ll still very slowly keep doing their thing, so the flavour of the yogurt will continue to develop.

Other notes

Local yogurt!

The yogurt you buy in the store uses a mix of a small selection of standard, lab-grade bacteria. This keeps things predictable and repeatable, characteristics that are required for mass production, but it doesn’t really do a lot for adding flavour or interest to a yogurt.

Therefore, your first batch of yogurt will also use those same bacteria, so it may not be too interesting. That first batch, though, will have started picking up wild lactobacilli from the local environment. That’s good! These wild bacteria will give your yogurt a character that’s unique to your location (terroir). These locals will be outnumbered at first, but as you start each batch with a bit from the batch before it, they’ll start to predominate. Eventually the balance will settle out and you’ll have the yogurt that perfectly reflects your location. For me, it’s a fairly tart and funky yogurt. Conveniently, that’s the way I like it. :-)

How about other milks?

I’ve found that fat-free milk makes a uninteresting yogurt. It’s not worth it, in my opinion. Full-fat milk makes for a lovely, loose yogurt that holds onto its whey, so it doesn’t strain well but it doesn’t matter much unless you prefer a firmer yogurt.

I’ve not tried this with milk from another animal, only with standard grocery store cow milk. Will it work with sheep, goat, or buffalo milks? Sure, but it’ll be different. These each have their own percentages of lactose and fats that will contribute to a different yogurt. I encourage you to experiment.

What you should not try this with are lactose-free milks, either cow or vegetable-based (nut, soy, etc). The happy little bacteria that make this fermentation work are lactobacilli. They work on lactose to create lactic acid. No lactose? No yogurt. Many unhappy little bacteria. Don’t disappoint the bacteria; only use milks that contain lactose when trying this yogurt method.

WTH do I do with all this whey??

That’s a good question. Lemme know when you have a good answer.

Seriously though, whey has a lot of protein and is full of those same happy little bacteria. Drink it! Or use it to cook. Or add it to the compost pile. Or head to your favourite search engine and find the myriad ideas that people have shared over the years.

Me? I dump it. I make a 2-litre batch of yogurt every week or two and I can’t keep up with the amount of whey it generates.

Large batches

I have no idea how well this method scales up. The largest batch I’ve made this way is a little under a gallon (~ 4 litres) of milk, but a batch that size is a pain in the ass for me to strain with my setup and is just unnecessary for me anyway. A 2 litre (half gallon) batch lasts me for a week or so of breakfasts and it’s easy enough for me to make more, so why scale up?

You need a larger batch anyway? OK! I’d suggest using more starter then letting it ferment a couple hours longer. Experiment with it; you’ll figure it out.