We’ve been making our own yogurt at home for the last year or so. It’s really been more for fun than anything else. I have a hunch that it’s not exactly more economical (more on that at the end). But there is something that I find so exciting about the magic transformation that takes place. Another bonus is that we’re eliminating a lot of the waste that goes along with buying and eating yogurt on a regular basis (I mean, realistically one can only find so many uses for all of those plastic tubs).

There are lots of resources out there, lots of variables that you can play with, and a variety of options that will work – so don’t be too troubled if you find conflicting recipes. In fact, there are ranges of fermentation times and temperatures that you can use successfully. Here, I’m going to outline 2 methods: the precise approach and the laissez-faire approach. The precise approach is how we originally started making yogurt. When fermenting anything (especially dairy!), a precise approach from a reliable resource is always a good idea (we started off with Harold McGee’s: On Food and Cooking). Several batches of yogurt later, we began to get comfortable enough to “wing it”.

Several factors contributed to the confidence to go off-book here. Notable examples include a story about how my Oma used to make yogurt overnight on the heating vents, as well as a number of yogurt-making mishaps (including one time where the dehydrator went on the fritz right before I was ready to use it). Another push in the direction of a more carefree approach was our review of yogurt recipes: given that there are ranges of temperatures and times that will work, do we really need to monitor everything so closely? Different temperatures and times will yield different results (more/less sour, differences in consistency,…), so if we want to ensure consistent results every time then some attention to detail is important…but at the end of the day it will all still be yogurt, right?

The Precise Method

Ingredients:

• 650g milk (I like to use whole milk)
• 45g plain yogurt (most brands I’ve tried have worked, but it’s best to look for one with “live cultures”)

Tools Required:

• Probe thermometer
• (750ml-ish) glass jar with lid (clean, preferably sterilized with boiling water in advance)
• Dehydrator, immersion circulator (sous vide), or other device to keep your (pre-)yogurt at the right temperature.

Instructions:

1. Gently heat milk to 90°C in a small pot. Maintain at 90°C (as best you can) for 10 minutes, stirring frequently. If you’re working on the stove, chances are there will be some fluctuation in the temperature. A few degrees plus or minus is fine (don’t sweat it), but do keep an eye on it and adjust the heat on your stove as needed.
2. Remove from heat and let cool to 45°C. For me, this usually takes a bit more than 25 minutes. Of course, this time will vary depending on the ambient temperature, size and material of your pot, etc.
3. Meanwhile, preheat your dehydrator/sous vide/other device to 45°C.
4. Add yogurt to warm milk and whisk gently (you’re trying to blend it, not aerate it) until fully combined.
5. Transfer mixture to your jar and place immediately in the dehydrator (or whatever) for about 4 hours, until yogurt is set. Start checking around 3 hours, every 30-60 minutes until you have a better idea of the time (that said – I have definitely forgotten about mine for an extra couple of hours and no harm was done).

The Laissez-faire Method

*Disclaimer: Is it possible that something will go wrong with this approach? Sure. This nonchalant method leaves plenty of room for error. That being said, we have been making yogurt this way for quite some time and have not had any issues. Try the precise method (or any of the other variations of this method that are out there) a few times to get a feel for the process, then decide for yourself how/if you want to go rogue. The main thing to keep in mind is the role of temperature and time at each step: The milk needs to be heated enough (scalded) to denature certain protein molecules, making it easier for them to bond and ensuring a better network of bonds (i.e. firmer yogurt). When cooling the milk, think Goldilocks: it can’t be too hot when you add the yogurt as the heat will kill the live bacteria. You also don’t want it to be too cool or it won’t encourage the right type of activity (and could allow reproduction of the wrong kind of stuff). During fermentation, the bacteria is creating lactic acid (longer fermentation -> tangier yogurt) and changing the structure of the milk (liquid -> solid).

Ingredients:

• 650g milk (I like whole milk)
• 45g plain yogurt

Tools Required:

• (750ml-ish) glass jar with lid
• oven with working light

Instructions:

1. Gently heat milk until small bubbles and a little steam appear. Reduce heat to low and maintain for 10 minutes. Note that some recipes don’t call for maintaining temperature, so you don’t have to, but we think this extra step creates a better texture.
2. Let milk cool until “warm”, then mix in yogurt. If you’ve done the precise method a few times you should have a feel for the temperature you’re looking for. Some cues: warmer than room temperature, but not so hot that you can’t keep your hand on the pot. Meanwhile turn on your oven light (or prep other warming tool of choice).
3. Transfer to glass jar and place in oven with light on for 12 – 14 hours or until yogurt has set.

FAQs, Tips, Troubleshooting:

• What’s the best tool for the job? Why not just buy a yogurt maker? There are lots of kitchen gadgets out there that can simplify the process – sure, even including a yogurt maker. I hear most newer instant pots (programmable multi-cookers) also have a yogurt setting that helps with both the milk heating and fermentation process. Similarly an immersion circulator or water bath (for cooking sous vide), or control freak (if you fancy) can help to automate the temperature control process. That said, it’s pretty simple to begin with so long as you have a stove and somewhere that can reliably keep the milk in the right temperature range to let the bacteria do its thing. We have very limited kitchen real estate so I would definitely not buy a new tool just for yogurt.
• How should I go about tweaking a recipe to get the results I want? It comes down to understanding the different variables and their impact on the process. Some factors you can play with: fermentation time and temperature (lower temperature and longer fermentation will result in a different consistency than a hotter and faster fermentation; in general, longer fermentation will also result in a more sour/tart flavour), percent milk fat (higher fat milk will yield a creamier result, whereas apparently a lower fat milk will yield a firmer result due to extra proteins added to the milk). Of course, the simplest way to change the resulting texture is to strain the yogurt: empty the jar into a fine-mesh sieve and let sit for 20-60 minutes (or until desired thickness).
• I want to make greek yogurt, but I end up with less yogurt and it seems like a waste to toss the stuff that gets strained out. Suggestions? The yield is definitely less if you’re going to strain your yogurt, but there’s no need to toss the liquid (whey). There are lots of ways to use whey! It’s supposed to have good nutritional properties so some people will drink it or put it in smoothies – personally, we love to use any leftover we have as a substitute for water when making bread.
• Why don’t your recipes use milk powder? Some recipes (and some yogurts you find in the store) call for the addition of milk powder. This is supposed to help up the protein and result in a firmer end product. Personally, we’ve never found the difference to be too noticeable or worthwhile so we opt for omitting this.

Cost-effectiveness

I’ve always been skeptical about whether or not there are really any cost savings from making our own yogurt. Here’s a very unscientific cost comparison using some prices I pulled from a local grocery store website one day:

• Organic yogurt: $5.99/750g = $0.80/100g
• Organic milk: $9.99/4L = $0.25/100mL
• Regular yogurt: $2.99/750g = $0.40/100g
• Regular milk: $7.49/4L = $0.19/100mL

Based on an estimate of 650g milk yielding approximately 620-45=575g yogurt, and assuming 650g = 650mL milk (so according to the internet the density is about 1.03g/mL – close enough, yeah?) we get the following:

• Our cost: 650mL organic milk (at $0.25/100mL) = 6.5*0.25 = $1.63/575g = $0.28/100g organic yogurt
• Our cost: 650mL regular milk (at $0.19/100mL) = 6.5*.19=$1.24/575g = $0.22/100g regular yogurt

Can that be right? Someone check my math? That’s a big difference! I have been convinced that the cost difference was negligible, or maybe the other way around for the past year. Maybe because buying milk always feels so expensive (and we always seem to go through it so fast). Whatever the reason, I’m happy to report that it looks like I was wrong! Unscientific approach aside (yes – I only checked one grocery store, and yes – I only measured my yield that one time, and no – I am not going to estimate the electricity costs), I think the difference in cost is enough to be certain that it’s definitely cheaper to DIY in this case. Hooray! One for the good guys!