There's no compelling reason for any sane person to attempt to make his own Greek-style yogurt, of course. Fage yogurt, which is delicious, has been available around here for at least a couple of years, and these days, I can walk into the local supermarket and pick up other brands, as well. But, well, there's a backstory here, so I'll just get into it.
I've been dieting, and because I find normal (aka sensible) dieting to be a nuisance, I decided to go with something a little more extreme so that I could get it over with. A friend of mine recommended a program that he was on. It involved two protein shakes and one regular meal each day, except that for two days out of the week, you skipped the two protein shakes and the regular meal, but you continued to take the elixirs and the supplements, which you were also taking on the days when you ate normally. I am utterly hamstrung here by my strong personal aversion to scare quotes, but you should read the last two words of the preceding sentence as if there were scare quotes around them, because there was nothing normal about that diet. Still, I decided to try it for a month, so I went to some place on the Internet and registered, and they took $377 out of my bank account and sent me a box with four canisters of protein powder, three bottles of pills and tablets, and three bottles of elixir, all of which was chock full of bee pollen and aloe extract and eye of newt and the blood of extraterrestrials.
Anyway, I followed this plan for a month, and I did, indeed, lose a significant amount of weight, but while $377 a month is not going to break me, it just seemed like an awful lot of money for what I was getting. I looked at the labels and figured that I could get very similar (or at least fully adequate) nutrition from a combination of yogurt, cottage cheese, and multivitamins. And you can buy a lot of cottage cheese for $377 a month. And, you know, it may sound like heresy, but when you're used to getting your breakfast from the McDonald's drive-through, a breakfast made of yogurt and/or cottage cheese blended with some frozen fruit is really very convenient and fairly tasty.
But it's significantly tastier if you go with just the yogurt. (I like cottage cheese a good deal, but I like it better either plain or as part of a savory filling.) The problem is that in order to get the same amount of protein that I was getting from the protein powder, I'd have to use a lot of regular yogurt. Regular non-fat yogurt has about ten grams of protein per hundred calories, so to get thirty grams of protein (what I wanted for breakfast), I'm at 300 calories before even adding the fruit.
Greek-style yogurt, though, has a very different nutritional profile. A 100-calorie serving of Chobani non-fat yogurt (my favorite: it's delicious and has five different kinds of active cultures) has 18 grams of protein. Exactly how this is possible, I have no idea. I know that Greek yogurt is made with milk that's been somewhat concentrated and that it's strained after it's made, but I really can't figure out why that makes such a difference. When I strain yogurt, it seems to me that most of what comes out of it is water and whey, and, since whey is protein, it would seem that most of the caloric loss would be from protein. On the other hand, strained yogurt is decidedly less tangy than unstrained yogurt, so perhaps much of what's lost is actually the lactic acid that the lactose turned into when the lactobacilli did their thing. Anyway, I've Googled and Googled until my little fingers were about to fall off, but I couldn't find a good explanation for why the 100 calories' worth of nonfat milk that had ten grams of protein and that became 100 calories' worth of nonfat yogurt with the same ten grams of protein becomes something that -- when you add enough extra to get back to 100 calories -- becomes something with 18 grams of protein. Maybe they do it with mirrors.
Anyway. No, really, I mean it this time: anyway. Anyway, I could just go and buy the Greek-style yogurt and use that, because when you're not spending $377 to make someone else rich to send you some protein powder and ground eye of newt, you can buy a lot even of Greek-style yogurt, which typically runs between $1.25 and $1.50 for a little 6 ounce container that provides 100 calories and eighteen grams of protein. But that pretty quickly becomes a lot of containers and a lot of money, even when you can easily afford it. So I though, heck, why not make my own?
As it happens, I was on vacation last week. The kids and I were staying in the remote part of Southwestern Pennsylvania where my folks have their summer home. I figured (correctly) that I couldn't get Greek-style yogurt there. I suppose I could use any sort of active-culture yogurt as a starter, but why not use my favorite brand with its five different active microbes? So I packed a couple of six-ounce containers of nonfat Chobani in my cooler and took it with me. I was able to find the other supplies there.
The other supplies in this case were skim milk, nonfat milk powder, some discarded food containers, a cooler, a thermometer, and a fine mesh paint strainer bag (which I acquired from Lowes, in the paint department). I figured that in lieu of trying to concentrate the milk through evaporation, I'd add some nonfat milk powder. I washed everything very thoroughly, then I poured a gallon of skim milk into a stockpot, heated it up until it was near the simmer (the thermometer I found only went up to 125 degrees Fahrenheit), stirred in a cup of nonfat milk powder, put the lid on the pot, and put the pot in a sink full of cold water until the temperature fell to 110 degrees. Then I whisked in about a third of the container of the Chobani (because I wanted to eat the rest). Then I poured the mixture into the emptied and cleaned ice cream tub and put the covered tub inside the cooler. I added 115-degree water to the cooler until it was near but not to the top of the ice cream tub, sealed the cooler, and let the whole thing sit for twelve hours.
In the morning, I had yogurt. It was a little bit thin, still, but it was still very warm, so that was to be expected. And it tasted suitably sour, though, in retrospect, I probably should have let it get sourer. I stuck the covered container in the refrigerator for the day, and then when I got home from an outing with the kids, I put the big mesh bag in a colander, poured the yogurt into the mesh bag, set the colander back over the ice cream tub, covered the top with plastic wrap, and put the whole contraption back in the refrigerator to drain overnight.
And the next morning, I had over a half-gallon of something that was a whole lot like Greek yogurt. It's the nature of Greek yogurt to be less tangy than regular yogurt, but mine was less tangy still, and while some people might prefer that result, I would have liked a bit more acidity (the texture is exactly right). Still, it was a great topper to my turkey-lentil chili, and it went marvelously with fresh fruit. And, well, wow do I have a lot of yogurt. A half-gallon didn't seem like all that much at the time, but it sure seems like a lot more now that I'm working my way through it. It does do a great job in a protein shake, in part because the flavor's very mild, and it's still very good with the fresh fruit. And it was a significant cost savings, and, truly, a lot of fun to make.
Next time, I'll likely go with more nonfat dried milk and a longer incubation period, but otherwise, the process worked pretty well and wasn't at all difficult. I think that -- even after I'm off the diet -- a cup-and-a-half or two cups of the yogurt blended with some good frozen fruit and perhaps a few ice cubes will continue to make a good weekday breakfast.
By the way, if you're like me and you can't resist buying the big bag of limes at Costco and so come home and zest and squeeze all of the ones you're not going to use immediately and put the juice in ice cube trays and then put the frozen lime juice cubes in ziplock bags so that your significant other can't say that you're always wasting food, you can take one cube of lime juice, let it melt, mix it with two tablespoons of sugar (I use Whey Low, as usual), and then stir in about two cups of plain, nonfat Greek-style yogurt. The result is divine. (If you don't agree, try adding another tablespoon of sugar. I won't tell anyone. I like it best with just two tablespoons, though.)