It’s taken too long for me to actually do it, but now I HAVE!! I’ve made homemade yogurt! Correction – WE experimented with making homemade yogurt! Despite my love of all things microbial and my dislike of spending lots of time cooking, I’ve not really made much fermented foods other than pickles about 15 years ago. Those days are changing! Several friends along the way have encouraged me to make homemade yogurt, but reading the book The Good Gut pushed me over the edge. Certainly we go through a ton of yogurt and heck – what kind of microbe-lover am I to not make fermented foods?

Ever since getting pregnant with Emily, my mid-morning snack has been a cup of plain Greek style yogurt that I add fruit to. Yogurt, especially the thicker Greek-style, is the one thing all members in my family enjoy – and so do our microbes. It’s a fabulous substitute for sour cream and often adds depth to butternut squash soup. Funny – reading this – it sounds like I like to cook and am a foodie. Truth is, that’s my husband, but I guess he’s teaching me to appreciate food more nowadays.

So – how did we do this? Simple. All it takes is heating up some milk, plopping in some bacteria to do all the “cooking”, and I get to sleep (hopefully) while the bacteria do all the work. Like one friend said, “It’s like magic”. Oh so true!


  • Get out your culturing containers. We used glass mason jars and a cooler. One friend does his culturing in an insulated thermos. I’ve heard of people using crockpots.
  • 2015_08_milkIn a dutch oven, thick bottomed pan, or double boiler heat up 4 cups of whole milk per yogurt starter to 180 °F. Our candy thermometer was handy for a change!


  • Stir so milk doesn’t stick to the bottom.
  • Let the milk cool to 115 °F.
  • Pour into jars.


  • Add ¼ c of starter culture, the contents of a probiotic capsule, or a commercial yogurt starter.Waiting for the milk to cool before putting into the jars. Note the starter cultures lurking in the background.
  • Whisk, gently
Adding the starter cultures. Bacteria – it’s the only culture some of us have!
  • Cap the jar.
  • Incubate overnight in a pot or cooler with a few inches of water around 105-115°F.
Cultures incubating in cooler
Cultures incubating in cooler
  • Sleep (my favorite step!)
  • In the morning move the jars to the fridge to set up a bit more.
  • Have a taste test
The taste test!! a) Greek yogurt, b)Single strain probiotic, c) Kefir, d) Multi-strain probiotic, e) unboiled milk control, f) regular yogurt

Easy peasy – eh? Yeah, the trickiest thing is getting the temperature right and I was probably a little more attentive to that than one needs to be. Sometimes my kitchen is more like my lab bench.

So with our experiment, we decided to play a little with different starter cultures. This is just me. I can’t simply make yogurt for the first time – I have to do an experiment with several different cultures. Simple isn’t really what I do. Thankfully, my girls were really excited about this and with lots of starter cultures everyone got to do something. Here’s the list of starter cultures:

  • Greek yogurt containing
  • A single strain probiotic
  • Kefir
  • A multi-strain probiotic
  • Regular yogurt
  • Unboiled milk


In another post I’ll talk about the actual microbial members doing the work.

All the samples – including the control milk – set up. I was surprised at this, but in later reading one of hubby’s books: On Food and Cooking: The Science and Lore of the Kitchenevidently it should gel! Rock on! What seemed odd was that only two jars had a yellowish liquid, the whey, on the surface.

Moment of Truth – The Taste Test

Finally – the taste test. Taste tests are something my husband often suggests and are lots of fun. Previous house hold taste tests: What apple varieties do we all like? Does Jac REALLY like white bagels more than multigrain (answer is NO – she doesn’t! ha!!)

To make it fair, I randomly numbered the tops of the jars and scooped a sample into bowls. One thing was quickly apparent – where fermentation had occurred, the texture was grainy or lumpy. The boiled milk was smooth. It was also really sweet. That was the milk sugar or lactose that had been broken down by the boiling. When that lactose is fermented – or digested by the bacteria – it is turned into lactic acid. It’s the lactic acid that gives yogurt a sour or tart taste.

Tasting helped us hone in more as to which bowl had what yogurt starter. Two bowls tasted like unflavored yogurt; they were the ones that had had the yellowish liquid on top. We all liked the flavor of the greek yogurt the best. The kefir-starter was the tartest tasting yogurt, with the multi-strain probiotic running a close second. The single strain probiotic was nasty tasting. In looking up more about this species in general, it was initially isolated from coagulated evaporated milk and can form lactic-acid. Perhaps it does, but we don’t care for the other by-products!

Issues and “Modifications for Future Experiments”

The one draw-back was the texture wasn’t very good. Also in reading the food science book, I’m wondering if I should have perhaps cooked the milk longer than I did. Maybe that would help?

I did drain some of the yogurt in cheese cloth to thicken it up a bit more and whisked it a bit and that helped a little. Still not the same texture as store-bought yogurt, but it sounds like commercial yogurt has additional thickeners. Still – I enjoyed it and so did the family.

Next – I’m going to mix a few different yogurts and probiotics together and see how that changes the taste. Might even break down and buy bacterial cultures – we’ll see. Also thinking of going to some of the fabulous local organic dairies around our house and using some of their farm fresh milk.

If any of ya’ll have more experience in this and can give me hints on how to get a better texture or what starters you prefer, please let me know in the comments section! I’d love to hear your experience. If you have any starter cultures you like – I’d love to hear. My friend Ming has already pointed me to The Art of Fermentation: An In-Depth Exploration of Essential Concepts and Processes from around the World. Looks like the author will even be in Baltimore soon for a workshop. hmmmmmm I might start enjoying being in the kitchen if my microbial pals are doing most of the work.


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5 thoughts on “The Great Yogurt Experiment – Test 1

  • October 6, 2015 at 3:02 pm

    Hey, I just found your blog through Science of Mom, and you have some really neat stuff here! The microbiome is a topic of great interest to me, so I think I will enjoy hanging around here for awhile to see what else you have to talk about. 🙂

    Homemade yogurt? Yum! I enjoy making it, and do so quite often. I make yogurt in 2 quart batches, pour in a casserole dish, cover with saran wrap, put in a barely warm oven. During the day I turn on the oven for 10-30 seconds at a time, a couple times during the day. Just leave it sit overnight, the oven holds heat quite well. My favorite starter culture is to use 2 tablespoons of Dannon Oikos Greek yogurt. I’ve tried a bunch of other brands/styles, they all work, I just get more consistent results with the Dannon and I like the final flavor the best. I also sometimes use a yogurt starter culture I bought from Natren.

    Incubation time varies widely. In the summer, 12-16 hours is plenty, in the winter, it may need 24 hours.

    Not sure what you didn’t like about the texture. Knowing that would help me know what to tell you! Sometimes it comes out kind of slimy for me, I do not know for sure why that happens but I think it is when the temperature wasn’t warm enough for long enough. Sometimes I get little grainy bits – that is when I was not being attentive to the milk while it was scalding. If the milk forms a skin on top, or cooks on the bottom, those solids will break up into gritty bits in the yogurt. To get the texture nice and thick, I line a colander with a dishtowel and pour the yogurt in. Cover with saran wrap and put in the fridge for a few hours (or longer if you want it thicker). I catch the whey in a bowl and use it for cooking. Its a great substitute for buttermilk, usually I use it in pancakes, biscuits, or muffins. You can add powdered milk (I use 1/2 cup) to the regular milk to help thicken it so you get more yogurt and less whey in your final product. I also usually pour the yogurt into a bowl and mix it with my electric mixer. I like the texture better when its been thoroughly mixed like that.

    I hope some of those ideas help you to get the yogurt you are looking for next time!

    • October 6, 2015 at 3:15 pm

      Wow, Marie – thanks for stopping by and for the fabulous tips! The texture issue was that it wasn’t very smooth, even after letting it drain through cheesecloth in a colander for several hours. So glad to know how to use the whey too. Also good to know about the incubation time since winter is certainly coming for us. 🙂

      Do you do any other fermented foods? My husband and I had a lovely “date night” a while ago when we went to a Sandor Katz workshop. Really inspiring workshop, but life has gotten in the way of us doing any experiments. We’re thinking of starting a kimchi if you have a favorite recipe.

      • October 6, 2015 at 3:54 pm

        For not very smooth, my suggestions are to stir the milk pretty much constantly while it is scalding (I like to use a whisk, and I have a rule that I MAY NOT LEAVE THE KITCHEN while the milk is heating otherwise I forget and am gone too long). Also, try mixing thoroughly with a handheld mixer. I suppose you could try a blender, but I never have because it seems to me that might ruin the texture by cutting it up too much. Best of luck on your further yogurt adventures!

        Sorry, yogurt is as far as I have gone into fermented foods. The motivation there was simply that its easy, we eat a LOT of it, and Greek yogurt is expensive. So sometimes I supplement by making my own.

        • October 7, 2015 at 9:43 am

          Thanks, Marie! I’ll try that next time. We didn’t stir constantly. That might also explain why our “control” with milk only curdled as well. Greek yogurt IS expensive and we eat a ton of it too. I’ll let you know how the next batch turns out.

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