Friday, 2 May 2014

A Crash Course in Home Made Yogurt

Good and good for you! Now you can learn how to make your own yogurt at home. Photo source Wikipedia, used under creative commons.

The key to making good yogurt is remembering at all times that you’re dealing with a living food. If you remember this at every step, you’ll avoid most of the pitfalls associated with yogurt making.
In its simplest terms, yogurt is the result of milk being fermented by a bacterial culture. The bacteria eats the naturally occurring sugars, lactose, in the milk. In turn, they give off lactic acid as their waste product. Lactic acid gives us yogurt’s distinctive tangy taste. Secondly, lactic acid changes the structure of the protein molecules in the milk, thickening the previously liquid milk into a semi-solid with the creamy texture that we so enjoy.

 So what kind of milk should we use? 

Traditionally, any kind of animal milk has been used. In this area, most commonly available sources are cow milk and goat milk. In other parts of the world, people make the yogurt from sheep’s milk or water buffalo or even camel.

An excellent source of calcium! Photo source Wikipedia, used under creative commons.

Any type of milk will do: full fat, 2%, skim milk, or you can even get decadent and mix in a little cream. Adding cream is helpful when you are looking for someone who needs lot of calories, such as someone who is recovering from some types of medical treatments. Of course, there are those people avoiding dairy consumption for ethical reasons or lactose intolerance issues. In this case, you’ll want to go with an appropriate milk substitute such as soy milk, rice milk, almond milk, or coconut milk. The only kinds of milk you really need to avoid are the ultra-heat treated, ultra-pasteurized milks in the foil tetra packs. These products are manufactured to be shelf stable at room temperature and consequently, are no longer an appropriate medium for fermentation.

Our top scientists have determined that milk from tetra packs is a no-go for yogurt making. Photo source Wikipedia, used under creative commons.

The second biggest factor is the presence of sugar. 

All natural milks have sugar in them: lactose. So if you’re working with a real animal milk that has not been treated to make it lactose free, you’re home free. If you are using any of the milk substitutes, you will require one that has been sweetened with cane sugar. Artificial sweeteners won’t work here. Your bacteria culture will starve to death.

The next thing that you will require is the bacterial culture. 

You can buy freeze-dried yogurt cultures online or in some of the grocery stores; however, these are really not needed. The far more economical approach is to take your favourite brand of yogurt and use 2 tablespoons of it as a culture in your batch of homemade yogurt. Of course, there’s some guidelines. Read the label. What you don’t want to see are the words “pasteurized” or “heat-treated”. The words you do want to see on the label are “live culture” or “active culture”.
Sorry, wrong type of culture. Photo source Wikipedia, used under creative commons.

Once you get going with the yogurt making, you won’t need to buy any type of starter. You’ll just keep a couple of tablespoons of last week’s batch, and use it to start the new batch. Yogurt will keep in the refrigerator for 10 days to two weeks; however, if your starter culture is more than a week old, you probably would want to replace it with something fresh. Since you need very little starter, you can buy just one of the little individual packages of plain, unflavoured, active culture yogurt. You’ll use 2 tablespoons, so you can eat the rest for snack.


You’re going to need: 
  • a heavy bottomed pot 
  • a probe thermometer
  • some heavy towels or blankets
  • a crock pot.

Note:  There are several methods for making yogurt at home that you can look on the Internet. You can use the oven. You can use a warming setting. You can use hot water baths. Personally, I find that the crock pot method is one of the easiest. The temperature remains stable and it gives me consistent results. Of equal importance, it helps me avoid having yet another piece of single-purpose kitchen equipment cluttering up my house.

Yogurt making steps

1) Plug the crock pot in and set the temperature to low. The purpose of this step is to heat the crock pot liner so everything stays nice and toasty warm.
2) Pour the milk into a heavy bottomed pot place on the stove to heat. You will want to use a medium-high heat. The idea here is to warm the milk smoothly without scorching. You are going to heat the milk to 180° F. The purposes of heating the milk is twofold. The first thing it does is pasteurize the milk, removing any potentially pathogenic bacteria. It gives us a clear slate, ensuring that the only bacteria that will be growing in it are the ones that we desire. The second reason is that heat helps break down the proteins of milk and this is what gives us a nice creamy texture we associate with yogurt. In other parts the world, people prefer their yogurt to have more rough or lumpy texture and so they don’t heat the milk. Here, we don’t particularly like “clabbered” milk products, so heating our milk to frothing temperature (180°F to 185°F) is an important step to ensuring that the product has a texture that we like.

3) Once the milk has reached a temperature of 180°F, we’re going to quickly cool it down to 120°F. The purpose of cooling this quickly is just to keep sanitary conditions intact. The ideal temperature for growing bacteria in this milk medium is between 105°F and 115°F. At 120°F, the bacteria start to die. So it is extremely important to make sure that the milk temperature is kept in this ideal growing range. This is why it’s so important to use a probe thermometer.

Remember: the thermometer is your friend. Photo source Wikimedia Commons, used under creative commons.
4) The quickest way to cool the milk is to partially fill your sink with cold water. Put the hot pot into this water bath and keep stirring the milk. Keep checking with your thermometer because the temperature the milk will drop very rapidly. The temperature is below 120°F, stop the cooling process by taking the pot from the sink.

5) Pour your milk into the crock pot that has been heating. UNPLUG the crock pot. We definitely do not want the crock pot to be turned on accidentally as the temperatures would destroy our yogurt culture.

6) Take a small amount, about a quarter cup, of the warm milk and mix it in with your starter culture. Thinning the culture out like this makes it easier to mix in with the entire batch of yogurt. Now pour the starter culture into the crock pot of milk and mix gently. Put the lid on the crock pot.

7) The last step is to cover up the crock pot. Using several towels or small blankets, wrap the crock pot completely. One layer should bundle up the entire crock pot. The additional layers can be just put on top because as you know, heat rises and were trying to keep the heat from escaping to the top of the crock pot.

8) That’s the end of our work in making yogurt. The rest is up to our bacterial friends. Leave the crock pot in and undisturbed place for 8 to 12 hours. The longer it sits, that tangier the yogurt will taste.

Finishing your yogurt

When you open up your crock pot, you may be disappointed to find that the end product is rather thin and doesn’t have the same creamy texture you associate with commercial yogurt. The reason for this is that you have not added the chemical stabilizers and thickening agents that are used by many commercial brands of yogurt. The way to turn your yogurt into something a little less runny is to strain the end product. Take a tightly woven cloth, like a clean kitchen towel, a muslin jelly bag, or a clean old T-shirt that nobody is going to wear again, and fasten it over a colander. Clothes pins are very handy for this purpose.

Alright T-shirt, you're going to a better place... Photo source Wikipedia, used under creative commons.
Place the colander over the collection container and pour your newly made yogurt into the lined colander. Put everything into the refrigerator and allows the liquid to drain out of the yogurt. If it sits for a couple of hours, yogurt will be a little bit thicker. If it sits overnight, the yogurt will be quite thick by morning. When you check on it, if it’s too thick for your liking, you can thin it out by mixing the straw-coloured liquid in the collection container back into your yogurt. This liquid is called “whey” and in later columns, will give you some ideas of how to use it.
There's a world of delicious toppings for you to explore!
In the meantime, feel free to explore different ways to enjoy your new yogurt. In Greece, they like to mix it with a little honey to sweeten it. You might choose to top it was some freshly cut up fruit or little dollop of maple syrup. Yogurt is a blank slate. How you dress it up is limited only by your imagination.

Thanks for reading. We’ll be back in subsequent weeks with the recipe ideas for your yogurt.

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