How to Make Tasty Bacteria That Grows in a Cooler


I’ve been having a smoothie for breakfast almost every morning for the past few months. It gives me that sugary kick start I need in the morning, I crave sugar less (ok, just slightly less) during the day because I know I get to have a sweet snack in the morning, it’s easy to eat when my stomach is not quite ready for solid food and I look forward to the morning because I get to have something super yummy.

The problem with having a smoothie for breakfast every morning is that I go through the ingredients rather quickly. It’s not much of a problem since Costco has huge bags of frozen berries and mega jugs of juice, but I do wish their gynormous container of yogurt came in a non-fat variety. I had been switching between their large cheaper fatty version and Trader Joe’s smaller pricier non-fat plain yogurt, but it gets expensive and it’s a pain to go to the store regularly for yogurt or stock the fridge. Plus, what does one do with all those re-useable plastic containers?

I’ll tell you what one does, one makes their own yogurt at home and fills all those spare plastic containers right back up! As always, I followed the advice of a couple different recipes and incorporated the parts I preferred to create my own way of incubating bacteria. Here’s what I did:

  1. sterilize jars and measuring cup (assuming the cup is metal) by placing them in a large pot with a tight fitting lid. Add a couple inches of water and boil covered for ten minutes. Do not remove lid until ready to use sterilized items. (warning: they will be hot!)
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  3. Measure 7 C of milk into pot and bring it to a boil or near boil. (You can add powdered milk as a thickener. I did not.) Stir the milk occasionally and keep an eye on it. Once boiling, remove the milk from heat.
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  5. Let the milk cool to about 118°-115°F. You can put the pot in cold water to speed cooling.
  6. Measure ~1/4 C plain yogurt (read the carton’s label to make sure it has live cultures) in the warm milk and stir until it is smooth. Remove any skin from the warm milk.
  7. Warm fresh clean water to 55°C (130°F) and pour it into a clean cooler. I use the water leftover from sterilizing the jars. Carefully set the jars of inoculated milk in the water so the bottom of the lids are above the water.
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  9. Check to see that the water in the cooler is not below 50°C (122°F) or above 55°C (130°F).
  10. Close the lid and do not open for 6-8 hours. If it sits too long it will become sour, if it is not long enough it will be very thin or so I’ve read, but have not noticed myself. The best thing to do is experiment and determine how long it needs to incubate to create what you desire.


One site instructed that once the whey (the liquid part) is separated, it means that the yogurt is not going to get thicker. Unless you use powdered milk, it will be thinner than yogurt you buy at the store, but I carefully pour out the whey after six hours and it’s thick enough for me.

I have also read that putting it in the freezer for a while after incubating and before storing it in the fridge will lead to a smoother consistency. I took “a while” to mean a few minutes since I can’t imagine freezing it would be good for the consistency.

Have fun growing bacteria!


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