Homemade yogurt 自家製ヨーグルト

We do not like low-fat or non-fat yogurt. We go for the full fat version. Our favorite is Seven Stars Farm Yogurt from Pennsylvania. The only place we can get this is at Whole Foods. Even before Covid-19, we had periods when even regular plain Dannon yogurt was not available at our grocery store. This occurred at the start of Covid-19. In the face of this shortage, my wife decided to start making her own yogurt again. This is something she did many years ago as a means of milk inventory control. She used a recipe given to her by a Palestinian friend whose family used it to make yogurt in the middle-east. Unlike other recipes which require pedantic small jars heated for a long time in a yogurt heating appliance, this recipe can make large quantities of yogurt overnight in "one sitting". This recipe uses commercial Dannon yogurt as the seed. We remembered it as a success but my wife has not made it for sometime. Nonetheless, she found the old recipe and made a batch.

According to this recipe you can use any quantity of milk with any fat content. If using low fat milk, however, add 1 1/2 cups nonfat dry milk (NFDM) for every 1/2 gallon of low fat milk. (This boosts the volume of milk solids in the milk making the resulting yogurt thicker). Bring the milk to a boil. Add the NFDM and allow the milk to cool in a bowl until it reaches 110 to 115 degrees at which point add 4 oz. of Dannon plain yogurt. (The same amount is used regardless of the quantity of milk). Wrap the seeded bowl of milk in several towels to keep it warm overnight. The next morning you have yogurt.

My wife used to heat up the milk in a dutch oven but this was the most tedious part of making yogurt since you have to continuously keep stirring it to keep it from boiling over and to prevent scorching on the bottom. She read somewhere that a slow cooker could be used to heat up the milk. So, we took our slow cooker, which we have not used for ages, out of storage. She heated the milk in the cooker set on low for three hours then turned it off. She took about a cup of the hot milk and using an immersion blender added the NFDM whipping it until all the NFDM dissolved. She then added the whipped portion to the rest of the milk and stirred it until everything was incorporated. (She did this because she found from experience sometimes the NFDM does not dissolve completely and forms an unpleasant layer in the yogurt on the bottom of the bowl). She let the milk cool for two hours until it was about 110 to 115 degrees before inoculating with the seed yogurt. She put the slow cooker bowl with the lid on into an ice chest to keep it warm overnight. The final product is shown below.

As you can see the consistency of this yogurt is quite different from the original Dannon. It is, nonetheless, quite firm and creamy. A major difference as shown by the yogurt dripping off the spoon is that it is very elastic. When the bowl is gently shaken it jiggles almost like jello. My wife made some Greek yogurt from this batch. The resulting Greek yogurt is very creamy and a dip we made using the Greek yogurt was much better than one with just strained Dannon. I also made some salmon salad and potato salad using this yogurt and it was much better and creamier than when I use the regular Greek yogurt.

My wife also learned that she was not alone in this yogurt making endeavor. While people were stuck at home during Covid-19, they were making yogurt in addition to baking bread. She read an article in the Washington Post about yogurt starters from "Culture for Health" and ordered some. The heirloom yogurt starter she got contained 4 different kinds. She used the "Viili" starter first which is described as "A Finnish yogurt variety, very mild and creamy, with a fairly thick consistency. It’s a versatile favorite that’s perfect on its own or in any yogurt recipe." According to the recipe, this starter does not require a heated environment. Following the instructions she used one cup of cold 4% milk and dissolved the starter in a glass jar, covered it with several layers of cheese cloth fastened by rubber band around the opening.

After 24 hours, it was still basically a glass of milk. The instructions said it could ferment for up to 48 hours. By then it had congealed a bit but was still basically a drink of milk rather than yogurt. She moved it to the refrigerator. The instructions recommended refrigerating it for at least 6 hours before tasting. The picture below shows the batch after a few days in the refrigerator. It firmed up a bit and had some curd. It also had a nice tangy/acidic yogurt flavor without any "off" taste. But it was way too runny.

Somewhat disappointed she fired off an e-mail to the company explaining the situation and asking for advice. They responded very quickly saying that the dried starter may take some time to fully "wake-up" to its full potential. As long as the first batch still smelled good they recommended starting a new batch using the ratio of one tbs from the 1st batch to 1 cup of cold milk. They recommended making 1 to 2 cups with that ratio (no more no less). Then they suggested she make successive batches with the most recent batch as starter until the desired consistency is attained. My wife used 2 cups of 4% milk with 2 tbs of the first batch for the second batch. After 48 hours it congealed significantly more than the 1st batch. The picture below is after 1 day in the refrigerator. It coagulated a bit more with a creamy consistency.

She then used 3 tbs from the second batch with 3 cups of milk for the 3rd batch. It was yet more solid (below picture). In addition it firmed up in 24 rather than 48 hours. We thought this consistency was not bad. She then used 4 tbs of batch 3 with 4 cups milk for batch 4. As shown below, after 24 hours this is just the right consistency and has developed a more pronounced tangy yogurt flavor. Success!

Well, now we have no shortage of yogurt. We have two options for making it and both are very good; one for low fat milk that results in yogurt that tastes like full fat and one for "high-octane" i.e. 4 % fat milk. It's a good thing we like yogurt and eat a lot of it. As long as milk is available we will no longer ever be without yogurt.