Introduction: How to Make Nonfat Greek Yogurt
This is an entry in the
Science of Cooking
I wear an apron and not a lab coat, so when I learned the process for making yogurt at home, I was fascinated. All you need is milk and a small container of yogurt and science does the rest. I made my first batch expecting to be disappointed. The opposite was true. For the first time, I actually liked the taste of plain yogurt. Now I make yogurt once a week. Specifically, I make nonfat greek yogurt using a yogurt maker. Here's how I do it.
Step 1: Tools & Ingredients
- Yogurt Starter (1/2 cup store bought plain yogurt or 1/2 cup saved yogurt from your last homemade batch)
- 5 1/2 cups milk (not ultra-pasteurized)
Set time: 9 hours.
Strain in refrigerator: 1 hour.
Estimated yield: 1 3/4 cups greek yogurt.
Estimated nutritional value per 6 oz serving: 100 calories, 0g fat. (per documentation from Dash Greek Yogurt Maker).
- Pan. Non stick is recommended for easy cleanup.
- Cooking Thermometer. I use the kind that you can clamp to the pan
- Yogurt maker (Optional. See step 5)
- Ice bath (optional)
- If you prefer thicker yogurt, mix 3/4 cup powdered milk with the 5 1/2 cups milk
- Take the yogurt starter out of the refrigerator at the start of the process. It will need to be at room temperature when you get to the mixing step.
Step 2: Heat Milk
Heat milk to 180 F. This takes me about 45 minutes. The milk shouldn't boil, so I use a med-low setting. I use a thermometer that clips to the pan so I can instantly see the progress. Note the thermometer in the picture. It has 180 degrees marked. I find this really helpful.
During this step, you will likely see milk skin form. If this bothers you it is easy to remove with a fork. Otherwise, you can just stir it into the milk.
Step 3: Cool Milk
Remove the milk from the stove and place it in an ice bath to cool to 110 degrees F. 110 is marked on the thermometer for this step also. With an ice bath, this step takes about 10 minutes. Keep an eye on it. You don't want it to go below 110 before the next step.
- An ice bath is handy to speed up the process, but it is optional. Alternatively, just let is cool naturally.
Step 4: Mix Milk and Culture
Make sure the starter is at room temperature. Add it to the yogurt maker container. Add milk. Mix gently.
Step 5: Keep It Warm and Wait
Now everything is in place. The milk has been prepped with conditions that are ideal for the bacteria in the starter to grow. A yogurt maker will be used during this step. It will maintain the proper temperature and keep track of the time it has been culturing. The folks who make the yogurt maker recommend culturing 9 hours when using skim milk. This generally works for me, but if it is firm enough, I find that 8 hours is enough. The longer it cultures, the more sour and firm it will be.
Note the photo with the spoon resting on the yogurt. This shows the firmness of the yogurt. Note the liquid in and around the spoon. That's whey. The whey will be removed in the next step.
- Since the goal of this step is to maintain a warm temperature, a yogurt maker isn't actually necessary. I am told that some people put it in the oven with the oven light on and this keeps it warm enough. Others put it in a container and keep it warm with a blanket. I like to keep things simple, so I prefer a yogurt maker.
- Since the bacteria eats the lactose, culturing longer means less lactose. That's why some people with lactose issues can tolerate yogurt, but not milk.
Step 6: Strain
When making regular yogurt, straining is not applicable. However, since this is Greek yogurt, this step involves using an ultra fine mesh strainer or cheesecloth to strain the liquid from the yogurt. The liquid is a watery yellow substance called whey. Since this is nonfat yogurt, there will be more whey than fatter yogurts. A strainer and a second container come with my yogurt maker. This allows me to easily strain from one container to the next. I generally end up with about a pint of whey.
- Save the whey in a jar and put it in the refrigerator. It is good in soups and smoothies.
- For best results, put in the refrigerator while straining. Set your clock for an hour. If you strain for longer, too much liquid will be removed and you will have something that resembles cream cheese.
Step 7: Store
Store in jars or an air-tight plastic container. I like to make berry jam and put 2 tablespoons at the bottom of a mason jar. Top it with yogurt and you have yourself a container of fruit at the bottom yogurt. Yum.
We have a be nice policy.
Please be positive and constructive.
45 minutes seems an AWFULLY long time to heat the milk?
Thanks for your excellent information Cheese Queen. I knew the "how" behind the process. Now I know the "why".
The reason your recipe called for 45 minutes is because it takes TIME to denature the milk proteins, which is part of what allow the proteins to bind to one another and make a strong curd.
You can, if you wish, bring your milk up to 180° quickly, but you'll want to maintain that temperature for at least 5 minutes and preferably 15 minutes, so the microwave won't work well for this process.
Even if you don't or can't denature the proteins, your milk will still make yogurt, but it will have a looser structure and will "stir out" more easily. Since you want to make Greek (strained) yogurt, perhaps this won't matter to you
If you care about the science, yogurt is technically an "acid set" cheese, which means it depends strictly upon low pH to cleave the protein bonds in the casein rather than a rennet which is used for hard or storage cheeses.
I have made cheese and fermented milk products professionally for many years. Making it at home can be challenging!
I agree. I was surprised too that it takes so long to reach 180 degrees F on medium low. I usually start heating on medium-low and then change to low when skin starts to form. This takes a bit longer. I checked another source and the time is similar. One of these days, I'm going to try the microwave. If you get different results, please let everyone know. Thanks for your comment.