Homemade Yogurt (read on…it’s surprisingly easy…and scientific!)

Over the next few weeks, I’m going to be moving my blog journey to the kitchen!  I’m going to be sharing with you a few of my favorite, fun and creative adventures in the kitchen.  I want to preface this adventure by telling you that when I left the professional science world to stay at home, I missed the thrill of “doing science” for a while.  Don’t mistake me here, I was NOT bored or needing anything else to do.  My mind was consumed lots of other things. I’m just saying that I didn’t have very many non-cleaning related scientific challenges.  That is, UNTIL I learned to make my own yogurt.

About six years ago when my oldest was a baby, I was very particular about what kind of food he ate and going through a long line of reasoning (including our budget, food quality, the thrill of the challenge), I decided to learn how to make yogurt for him.  I won’t go into all the reasons why yogurt is good for you…there are lots of other great articles on that, like the one here.  Instead, I want to spend our time today teaching you how to make yogurt!  After several years of learning, tasting, testing and trying, here’s the easiest, most fool-proof method for making yogurt I’ve found.

Budget

Around here a quart of decent yogurt costs $2.50 or so.  Even better yogurts and Greek varieties are higher.  Meanwhile, a gallon of good milk costs $3.69 and up.  So, if you made that gallon of milk into a quart of yogurt, it would cost you $3.69 per gallon or $0.92 per quart.  Since we eat a lot of yogurt, this is a decent amount of savings for us.

Ingredients

1/2 gallon milk (or milk substitute)

1/4 cup non-instant milk powder (or 4 tsp. gelatin)

1/4 cup plain yogurt (or yogurt starter)

Materials

2 quart size glass jars

thermometer

1 or 2 large pots

funnel

heating pads

towel

Preparation

1.  Sterilize 2 quart size glass jars and a funnel.  Fill the jars with water and LOOSELY place the lids on top.  Place them into a water bath (that is, a saucepan filled half full of water).  Heat over high to a boil.  Alternatively, you can wash the glass jars in a VERY HOT cycle through your dishwasher, but you’ll use the hot water later, so it may save you some time to do it this way.  This step kills any germs on your glass before you add your yogurt and set up the perfect environment for growing bacteria.  So, you want to make sure the only bacteria you’re growing are the “good” bacteria from your yogurt/yogurt starter.  Don’t stress…just sterilize.

2.  Meanwhile, place 1/2 gallon (8 cups) of milk into a saucepan and heat over medium heat.

3.  Once the temperature of the milk reaches 150 degrees Fahrenheit, remove the saucepan from the burner.  This step kills any residual (“bad”) bacteria present in the milk.  There may not be any bad bacteria in your milk or there may only be an insignificant amount for milk-drinking purposes.  However, even if there’s a very small amount of “bad” bacteria in your milk (which wouldn’t make you sick if you drank the milk because its numbers are just too small).  As you go on to the next few steps and introduce the “good” bacteria in your plain yogurt or yogurt starter, incubate the milk at the perfect temperature for growing bacteria, you’re going to grow ALL the bacteria in your milk, good and bad.  So, this step kills the bad bacteria before you add the good.

4.  Allow the milk has to cool to 110 degrees.  Add 1/4 cup of non-instant milk powder and 1/4 cup of plain yogurt or yogurt starter.  Stir until well combined.  You need to allow the milk to cool so that the milk is not so hot that it kills the good bacteria in the plain yogurt or yogurt starter when you add it.  The non-instant milk powder (or gelatin) is optional; however, it makes the yogurt thicker (which I prefer).

5.  Very carefully empty the water from your serialized glass jars and place the funnel in the top.  Then, very carefully pour the milk mixture into the jars using the funnel.  If you used a pot of hot water to sterilize your glass jars, save the water for the next step.

6.  Place the filled jars back into the water bath you used to sterilize the glass jars (or a fresh pot filled halfway with 110 degree water if you accidentally dumped yours or if you sterilized your jars using the dishwasher).  As you can see here, the temperature of my water is 125 degrees, since it’s going to lose some heat as I’m moving the pot around and setting up my incubation station I’m not worried that it’s higher than my ideal temperature of 110 degrees.  Also, 110 degrees is the goal, but realistically, I aim to stay within a range of more like 105-115 degrees.

7.  This time around I placed the pot, jars, and thermometer in a the oven (the oven was OFF).  I placed the setup inside to insulate it and help maintain the temperature of everything at 110 degrees.  In the past, I have tried using a burner on the stove to maintain the temperature, but it always seemed to get too hot…making that setup a hassle because I had to babysit it a lot to make sure the good bacteria in my yogurt didn’t die.  The BEST place I’ve found to place the pot, jars, and thermometer is in a cooler, which I believe works better than an oven.  Coolers are usually smaller and don’t have a vent like ovens do, so it makes sense that less heat would escape from them and you can more easily maintain a set temperature of 110 degrees.

8.  Once you’ve found a suitable place to insulate your water bath and help maintain the temperature at 110 degrees, cover the whole setup with a thick bath towel to insulate it further.  Close your oven door or cooler lid tightly.  Then, set a timer for 10 HOURS.

9.  Periodically, check the temperature of your setup.  I checked every 3 hours or so.  When I used the cooler, I believe I only had to add hot water once to my water bath to bring it back up to 110 degrees.  When I used the oven, I had to adjust the temperature about 3 times.  So, using the cooler setup, you could either make your yogurt in the morning and let it grow all day…or you could make your yogurt in the evening and let it grow all night.  However, the oven method probably works best during the day when you are able to check on it now and then.  In any case, once your yogurt is firm and looks like yogurt, remove it from the water bath and refrigerate it for 3-4 hours before enjoying your own, fresh, MADE BY YOU yogurt!  We like to sweeten ours with honey and vanilla.

10.  One more thing…if you like the even thicker consistency of Greek yogurt, take your CHILLED yogurt and strain it through cheesecloth (or a clean dishtowel) for 2-3 hours or overnight.  Enjoy the thicker yogurt on top and discard the liquid whey that drained out the bottom (or use it in a smoothie).

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