Making Yogurt at Home

I love requests! I just got one to do a post on how to make yogurt at home, which reminded me that someone else had previously asked about making paneer, which leads into the question of what to do with whey after you've separated the milk solids from it to make cheese (paneer).

So, one at a time, in this mini-series on homemade dairy products : ).

Yogurt

The basic concept behind yogurt is to allow certain helpful strains of bacteria* to culture and ferment milk.

• Yogurt is digestible by people who are lactose intolerant, because the bacteria that culture the milk break down the lactose in it - they "eat" some of it, and leave lactic acid as a by-product - hence that "tang" that yogurt has.


• Yogurt is incredibly nutritious and satisfying, being rich in protein, calcium, riboflavin, vitamins B6 and B12, and delivering to our gastrointestinal tracts an inoculation of "good bacteria." Our guts are all about population dynamics - imagine a war between good and bad bacteria: the more good bacteria, the less of a chance bad bacteria has.

I usually start with about a half gallon of whole, organic milk (I like Organic Valley or Ronnybrook). I take a pot, rinse it with water, pour the milk in, and scald the milk over medium heat.

[This does two things: 1) kills whatever else might be in the milk, so that later, when I "inoculate" the milk with the yogurt bacteria culture, it can spread like wildfire throughout the milk without competition; and 2) heats the milk, since ultimately I'm going to need the milk to be warmer than human body temperature for the yogurt bacteria to thrive.]

After scalding the milk, I let it cool away from the stove to a little warmer than human body temperature: 45 degrees Celsius or about 113 degrees Fahrenheit. [You can use a thermometer, or just taste test the milk, to figure out when it's ready: when it feels pleasantly warm and drinkable to you, like the temperature of a nice warm but not too hot shower, or a cup of tea that's cooled down just enough to become easily drinkable, it's ready. A hotter temperature would kill the bacteria.]

While the milk is cooling down, I preheat the oven to its lowest temperature (170 degrees Fahrenheit).

When the milk is that perfect, warm temperature, you stir in either live yogurt starter culture, following the directions for that (nowadays, freeze-dried starter cultures are sold in grocery stores like Whole Foods; Yogourmet is one brand), or a small amount of previously made yogurt (I like Erivan, and I add about half a cup's worth to a half gallon of milk; once you've started making your own yogurt, just save the last half cup to get the next batch started).

You have to then keep the mixture at that nice, perfect, warm temperature for 6-12 hours. I make yogurt at night, and leave it overnight, covered, in the warm, 170-degree Fahrenheit oven. (After it's reached 170 degrees and I've put the yogurt in, I actually turn the oven off when I go to bed, and the yogurt stays warm enough just being in that insulated place.) Other people keep it in a good thermos overnight.

In the morning, voila, you have home-made yogurt, just in time for your smoothie or yogurt-and-granola!

*Some yogurt-making strains of bacteria include Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, L. acidophilus, L. casei, and Bifidobacteria.