Saturday, March 2, 2013

Making Homemade Yogurt

Anyone that has spent even a small amount of time around me will know that I like to make things, and often it's not for the sake of saving money, but so I can say to myself that "I've done that" and strike it off my list of accomplishments - and sometimes it's because I'm intrigued into how something is made or done.  

Homemade Yogurt was one of those items, but as it is really simple and very cost effective, I now do it on a regular basis.  Having young kids and being generally a family with a heavy appetite for yogurt, there was no way we'd be spending about $15 a week on a few litres the stuff.  Instead, I spend about $4 and make about $15 worth.  As for time needed, the bulk of this is done whilst I sleep.

To give you the layman's background, yogurt is milk that has had a bacteria go through it, converting the lactose (a form of sugar) into lactic acid.  In other words, it's fermented milk.  The lactic acid then acts on the major protein in the milk ("Casein" - its the bit that holds all the calcium, phosphorus, carbohydrates and amino acids) and causes it to bind into a substance that you know as yogurt.

The bit that always confuses people is if you're making your own yogurt, where do you get the bacteria?  The good news is, you just buy some yogurt at the store with "Live" or "Active" cultures (cultures = bacteria), introduce it to some warm milk and leave it for a number of hours to chew through the lactose.  Literally, that's it.  You can save a bit of your new yogurt to create the next batch, but it runs out of steam after about six re-uses... at which point you'll probably want to buy a different yogurt from the store and try experimenting with that.

You'll see a whole bunch of recipes on the Internet that call for various paraphernalia and heating pads, towels, thermos flasks, and you really don't need any of it.

So, here's the recipe that I did.

The ingredients:
  • 1 liter of whole milk.
  • 3 tablespoons of plain yogurt with "live" cultures.

The method:
  • First, heat the milk to 185°F in a saucepan over a medium heat. Keep stirring as you don't want to burn the milk on the bottom of the pan.  This is just to sterilise it of any bad bacteria you might have in it, and it breaks down the milk structure to make it easier for the bacteria to process.
  • Now, turn off the heat.  Let it cool to 110°F.
  • Add 3 tablespoons of store "Live/Active" yogurt.  Mix well.
  • Pour the milk into a suitable container with a cover.
  • Pop it into an oven with the light on.  (In my oven, the lamp alone warms things to 90-91°F).
  • Go to bed, leaving it for about 10 hours.  Do NOT jiggle, jostle or poke it once in the oven.
When you open up the oven in the morning, you're greeted with what is unmistakably yogurt.  It's warm, but it's yogurt.  The longer you leave it, the tangier it becomes, the shorter you have it, the less tangy.

The next bit is all about preference for the yogurt style;  The yogurt you're looking at has a watery substance in it - This is whey (what to do with whey other than chuck it down the sink is a topic unto itself).  You can leave it and mix it in for a very runny yogurt, or take it out, to thicken things up a bit.  I elect to take mine out using this method:

1.  Put a sieve over a bowl.  Put a paper coffee filter or paper towel in the sieve.
2.  Spoon in as much yogurt as will fit and leave it for 5 minutes to drain.
3.  Spoon it out into a (sanitised) container for refrigerating.  

If you want to go greek style, put the strained yogurt in a coffee filter and leave it to strain in your fridge overnight, to remove even more whey.

So to recap:
  • Heat the milk to sterilize it and break it down.
  • Cool the milk to the point where the heat won't kill the active bacteria from the store bought yogurt.
  • Leave it in a warm place, undisturbed, to do it's thing.
  • Optionally strain out as much or little whey as you want when it's done.
That's it.  No machines.  No fancy ingredients (though obviously, feel free to add flavours, fruit, colours, etc - if you ever wanted blue yogurt that tastes like habaneros, well now is your chance).

If you use semi-skimmed or skimmed milk, it still works just as well, just the yogurt is a little more runny due to the lesser fat amount.... and the way the store bought yogurt deals with that is thickeners... you can probably just add some milk powder or cream if you really need thicker yogurt.