- As a kid, one of my favorite games
was the bacteria name game. You know the one, where you sit in a circle and everyone has to go around and say what their name would be if they were a live and active bacteria. I always went with Lactobacillus Dan-icus. (Dan laughs) What's that? You never played that game? You think it sounds like a terrible game. You want me to stop talking
and get on with the episode? (playful music) Yogurt is an incredibly important staple in cultures across the globe. Its exact origins are a little bit fuzzy, but historians believe
that it was invented, maybe discovered, somewhere around 5,000
B.C. in Mesopotamia. It makes sense. Fresh milk exposed to wild bacteria developed into a thickened
food that tasted great, was more shelf stable than fresh milk and could be used in countless ways. Today's yogurts are far more standardized than their predecessors. They contain specific
mixes of live bacteria, in order to deliver consistent results. There are tons of options for buying yogurt at the supermarket, and, I'm not gonna talk about any of them. I am going to show you how to make the best yogurt
that you've ever had. And, I'm gonna show you why yogurt is one of the
most versatile foods. We're gonna go hot, we're gonna go cold and we're gonna go frozen. So how exactly does liquid milk turn into lush, creamy yogurt? First, milk is heated to pasteurize it. This step improves the
milk protein's ability to set into a lovely creamy texture and it kills off any wild bacteria that could negatively impact fermentation. Then comes culturing. Live bacteria are added to the mix and left to do their work. They are pretty picky about temperature, so the yogurt needs to be held at about 110 to 115 degrees Fahrenheit for them to get down
to the serious business of yogurt making. Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus, are the two symbiotic lactic acid bacteria that you'll find in all
commercial yogurt here in the US. Almost all other yogurts also contain other species and strains. Fun side note, it was a Bulgarian scientist
named Dr. Stamen Grigorov, who first identified that
crucial Lactobacillus subspecies. Hence, bulgaricus. Those two bacteria (bell dings) work as a tag team to make yogurt. Bulgaricus kicks things off
by producing amino acids. Those help thermophilus grow
and produce lactic acid. And when the pH drops to five, that's when bulgaricus
comes back on the scene and takes over the majority
of lactic acid production. As the milk turns more acidic, the milk proteins form a
network that traps water and forms a lovely, soft gel. Okay, so I know this all
sounds like kind of a lot, but the truth is, making good yogurt is all about setting the bacteria up to do their thing, and then getting out of the way. Making your own yogurt is easy. And best of all, it gives you complete control over taste, texture and richness. Don't like sour yogurts? You never have to eat them again. Love the ultra smooth, decadently rich yogurts popular in France? You can make that. Want flavored yogurt but
without all that sugar? We got you. Let's go to the kitchen and check out Cook's Illustrated's Senior Editor Lan Lam's recipe for homemade yogurt. We are starting with
ultra-pasteurized milk. Why? When milk is given a very short, uniform exposure to very high heat, it leads to a yogurt with a
creamy, homogenous texture. Which, as it happens, is how ultra P milk is treated. It's heated to 275 degrees Fahrenheit for less than five seconds and then rapidly chilled. Next, we need our starter. Now once you get into
the yogurt-making habit, which you absolutely will, you can use some of your last batch to start a new batch. But just starting out, you'll need a commercial yogurt that says live and active cultures on it. Choose a plain yogurt that you like, because many of its characteristics will carry over to your homemade yogurt. We start by warming the
milk on the stovetop to 115 degrees Fahrenheit, which is an ideal temperature
for our bacteria to flourish. Then, we thoroughly whisk
in our store-bought yogurt to start the fermentation process. And then we'll transfer it
to some big ol' Mason jars. From here, you can ferment right in your oven. Just submerge the jars in
a pot of 120-degree water. Place the pot in a turned off oven, with the oven light on and add a second pot of boiling water. That second pot will emit heat to keep the bacteria in their
fermentation happy place. Or, if you have a sous vide circulator, you can do all of this
right on the counter. At the five-hour mark, we'll use a clean spoon
to taste our yogurt. If you want it tarter and thicker, just let it keep going. Fermenting time has a
big impact on thickness. Check out this experiment. Here, I have two batches of yogurt. One was fermented for five hours and the other was fermented for 10 hours. Now just look at that difference. Now, you're just gonna have
to trust me on this one because we still don't
have taste-a-vision, but the 10-hour yogurt is much more tart than the five-hour one. Beyond time, there are incredible
and incredibly easy ways to customize your yogurt. This is my favorite part. Want a richer yogurt? Substitute a half a cup of heavy cream for a half a cup of milk. Want a denser, creamier yogurt? Whisk a quarter cup of
non-fat, dry milk powder into the cold milk before heating it. Here is my favorite batch. It has the heavy cream swap, the additional milk powder and it's been incubated for eight hours. It is perfectly tart and
has a lovely richness. So good. Now I hear some of you saying, "Dan, that's too thin for me. I'm a Greek yogurteer." Well, straining this
yogurt couldn't be simpler. Place cheesecloth over
the mouth of the jar, screw on the lid ring and drain upside down in a measuring cup, overnight in the fridge. Okay. So I'm sure you don't need me
to tell you how to eat yogurt. It's your yogurt, your house, your rules. But, I really think you should make my ginger frozen yogurt recipe. I'm talking tart, ultra creamy frozen yogurt, with beautiful ginger flavor and burn. It is leaps and bounds
over the commercial stuff. I guess that's today's theme. I guess we're sort of like, homesteaders today. (Dan scoffs) Look at us, huh? Should we start making our own clothes? Yeah, I think that'd be pretty cool. (jangly frontier music) Actually, maybe we just stick
with making yogurt today. Our froyo couldn't be
simpler to put together. (playful music) We'll use our strained yogurt, and we're also gonna use some of the whey that we drained off. We're gonna sprinkle a
teaspoon of unflavored gelatin over a half cup of it. Gelatin is a classic and
old-school ice cream stabilizer. After we zap it to melt the gelatin, we'll stir in both
fresh and ground ginger. And here's the part of the show where I plug my episode on ginger. It is absolutely fascinating. If you haven't seen it, there's a link below the
video to check it out. Next, we whiskey whiskey
everything together. We have sugar, Lyle's Golden Syrup, a little bit of salt, our strained yogurt and our cooled and strained whey mixture. Lyle's Golden Syrup is gonna help us in the iciness department because half of its sweetness comes from two small sugars
called glucose and fructose. These help lower the freezing point of our frozen yogurt mix. That means more of the water in the base will remain liquid in the freezer, giving us a smoother, more scoopable froyo. Yo. Then, we fridge it until it's 40 degrees Fahrenheit or less, and then pop in our ice cream maker until it looks like soft serve. You can eat it fresh outta the machine, which I highly recommend, or you could transfer it
to an airtight container and then freeze until hard, which I also highly recommend. Now, if you aren't into ginger, we also have recipes for orange, strawberry and double mocha surprise. Wanna know what the surprise is? We don't have that flavor. It tasted really gross. But homemade yogurt opens
up way more possibilities than just dessert. Make a batch of tanabour, the impossibly silky, Armenian yogurt and barley soup, that gets finished with a drizzle of Aleppo pepper-infused butter. And don't forget about the whey. Save any that you drain off if you're making strained yogurt. It can be used as a buttermilk
substitute for biscuits, a starter for your next batch of yogurt, or my favorite use, sub it for an egg white in cocktails. Here is one of my fave gin drinks, featuring Aperol, lemon juice and orange bitters. For this one, I used an egg white. And for this one, I used
an equal volume of whey. Yes whey. You know, I think I'll start my meal with this whey-foamed cocktail, then tuck into a silky bowl of tanabour, and finish things out with a cooling bite of ginger frozen yogurt. Who knew yogurt could do so much? You knew? This whole time. And you didn't say anything? I need another sip of that drink. Okay, that's the ticket. I wish you could all
join me for this meal, because this is absolutely
how to eat yogurt. (comical music) Thank you so much for watching. I wanna give a huge shout-out to Streptococcus thermophilus and Lactobacillus delbrueckii
subspecies bulgaricus, as well as all of the lactic acid bacteria that end up in our yogurt. We couldn't do it without you. Now, I wanna play the bacteria
name game with all of you. So hop in the comments and let me know what your
bacteria name would be. Thanks again for watching
and happy yogurteering.
