I made yogurt! And it was easy!
As a lactose intolerant sort of person, yogurt is one of the few dairy products I can eat without significant consequences. In fact, it seems to keep my somewhat ornery stomach in check and I try to have a serving every day or two. However, all yogurts are not created equal and the high fat, low additive yogurt that works best for me is expensive, at $6.00 a tub! In addition to high cost, many of the yogurts on the market today are hardly representative of the yogurt that has been consumed by humans for thousands of years. They are extremely low in fat, high in sugar and contain setting agents such as gelatin, pectin and agar agar in addition to a variety of other additives and preservatives. I was pretty surprised when I learned that yogurt is not a complex substance that requires a long ingredient list, but just milk and a little bacteria. Once I knew homemade yogurt was possible, I decided to ditch the additives, containers and high cost and start making my own.
My yogurt-making technique:
(1) First, I heat two litres of milk over medium heat until it reaches a temperature of 180 degrees ferinheight (a candy thermometer can be used to measure the temperature throughout the process) while stirring regularly. I use a combination of organic whole milk and cream. You can use milk of any fat content you like, but higher fat milk will result in a thicker, creamier and more traditional product.
Heating the milk is necessary in order to unfurl the proteins of the milk so that they will set smoothly, rather than in curds.
(2) Next, I take the milk off the heat and let it cool, at room temperature, down to 110 degrees while I stir it occasionally.
(3) As the milk is cooling, I pull my yogurt starter (3-4 tablespoons of yogurt, either from my last batch or from a store bought yogurt containing live active cultures) from the fridge and let it sit at room temperature. Once the milk has cooled to 110 degrees, I add half a cup of the warm milk to the starter, stir them together and pour the combined mixture back into milk. I stir it up well to evenly distribute the bacteria.
If you add the starter back into the milk at a temperature above 120 degrees, you will kill the bacteria. If the milk is below 90 degrees, the bacteria will not be activated.
(4) Once the mixture is combined, I pour it into my yogurt maker, plug it in and leave it alone. My yogurt maker keeps the yogurt at an even temperature of 110 degrees throughout the incubation period.
Now that I understand the yogurt making process, I wish that I had bought a crock pot rather than a specific tool just for yogurt. Alternatively, some people use thermoses wrapped in towels, water baths, or a pot in the oven with just the pilot light on. If you do use a crock pot, you must make sure that your "low" or "simmer" setting remains at a constant temperature, somewhere around 110 degrees. This will vary based on crock pot.
(5) Next, I wait. The incubation process can be anywhere between 4 and 12 hours, depending on the type of yogurt you would like to achieve. A shorter incubation will results in thinner, milder yogurt that tastes very much like milk. A longer incubation will result in a thicker and more tart yogurt.
During incubation, the warm and cozy bacteria are multiplying and metabolizing the lactose in the milk. This process turns lactose (milk sugar) into glucose, galactose and lactic acid. Because I am lactose intolerant, I want to get rid of as much lactose as possible and wait through a full 12 hour incubation. The longer you allow for incubation, the easier yogurt will be to digest as the bacteria has already done part of the work in breaking down both milk sugar and milk protein.
(6) After the incubation period, you have a few choices. You can either put the yogurt directly in the fridge to set, strain the yogurt immediately or put it into the fridge to set and then strain it. I have attempted all three approaches and prefer the last. My goal is to produce Greek-style yogurt (it's not true Greek yogurt because I am not in Greece) which requires straining to reduce/remove the whey. Many people seem to confuse whey with whey protein (which is a very small component of whey), but whey is composed predominantly of carbohydrates (the broken down glucose and galactose). Removing whey leads to yogurt with a higher fat and higher protein content. Whey removal will also remove some nutrients, but everyone seems to have a different opinion on the content and importance of these nutrients. I just go with personal preference and the desire to eliminate as much lactose I as can. So, I let the yogurt set in the fridge overnight and then strain it in a muslin bag for a few hours.
(7) Once strained, I spoon the yogurt into jars for consumption. Two litres of milk will give around 5-6 cups of yogurt (and lasts me a week), but this depends on how much whey you strain out. I always set aside some starter from my current batch in a separate container and use it within 6 or 7 days.
(8) Eat! There are endless ways to use homemade yogurt. I often use yogurt in muffins in place of oil and in sandwiches in place of mayonnaise. But, my favourite way to eat yogurt is for breakfast, with a sweet topping of homemade cinnamon apple sauce, honey or homemade strawberry sauce. Yum!