(This link has the full article from 2012, which details how I make yogurt.)
I had a request, recently, for more information on how to make yogurt for dirt cheap. So, I thought I'd share what I do, and what I've found that works for me.
The primary cost is the whole milk. I look for it on markdown -- milk that is close to it's sell-by date. Turning milk into yogurt extends the life of that milk. So, if there's just 1 week before the sell-by date on the milk, I know that I can make it into yogurt the next day and have the yogurt still be good for another few weeks. Traditionally, yogurt-making was a simple food preservation technique. The yogurt contains cultures which produce lactic acid, which, in turn, retards spoilage of milk (see here, article in Mother Earth News).
So, buying whole milk when marked down, due to nearing the sell-by date, is my first step in making yogurt for dirt cheap (most of the time, I spend under $2 for a gallon of whole milk, which makes 3 1/2 quarts of thick yogurt). If I find more whole milk on discount than I need for yogurt-making right away, I freeze the milk and make yogurt at a later date.
My second step for dirt cheap yogurt is free yogurt starter.
I've been making yogurt for 2 1/2 years now, about 2 times per month. For my first batch, I bought one 6-oz container of Yoplait vanilla yogurt for 39 cents. I've been using descendants of that first batch for about 50 batches, now. Based on a price of 39 cents per container of Yoplait, I've saved over $19 on yogurt starter.
What's my secret? I have a method that seems to work for me. I freeze my own homemade yogurt as starter for successive batches.
Some people chain-yogurt (using a bit from each previous batch to make the current batch). I prefer to freeze my starter in quantities large enough to make several batches. The advantage, here, is that if I don't get around to making a new batch of yogurt for a few weeks, I have viable starter waiting for me in the freezer. Yogurt cultures only remain viable in the fridge for about a week to 10 days.
Every 4 or 5 batches, the day immediately following making a fresh batch (after I'm sure it has set), I scoop 6 ounces of yogurt each into 5 or 6 freezer containers.
This is important -- I wait until the day after I have made yogurt (and the yogurt has incubated in my cooler filled with 115F degree water plus has had a chance to finish setting-up in the fridge) to take some yogurt to freeze for future starter.
I label and date each container. Frozen yogurt can remain viable for many months in the freezer, but why push it. This last batch (1/6/14) was made with yogurt dated June 2013. So, I know for sure that my freezing methods work for 6 to 7 months from the point of incubating to the point of using it as starter. I keep these containers of starter in a 0 degree F freezer.
I never let myself use the last container of frozen yogurt, but always keep one in reserve, just in case I do something wrong in the yogurting process.
I've read that eventually the bacterial strains will die out, and I'll have yogurt that doesn't set. But I'm putting this off by freezing several batch-starters at a time. Meaning that I'm probably only about 8 descendants from my original batch made with the 39-cent container of Yoplait.
My yogurt costs me 55 to 60 cents per quart. For our budget, that is dirt cheap.
Update on freezing yogurt starter and its viability
It's March 2019 and I am still using yogurt starter from previous batches. I recently found 3 containers of starter in a 0 degree F freezer, dated June 2017. I successfully made batches of yogurt with that starter. The yogurt is just as thick as my original batches. My hope is that you have as much success with freezing 2nd day homemade yogurt to use as starter as I have.
Another update on freezing my homemade yogurt for use as starter
Here it is January of 2020. I never would have believed this would be possible but I am still using quantities of yogurt as starter which are descendants of that original container of Yoplait, bought in 2012. Yes, I've been freezing small amounts of each batch of homemade yogurt, then using those as starter for subsequent batches. I have never had to buy more yogurt to use as starter. The resulting yogurt is thick and tart -- just the way I like it.
Happy yogurting!
