I just stumbled on an old set of instructions I had written to use my yogurt maker, back when we lived in Egypt where the local fresh dairy products were of questionable cleanliness, and we had a little kid. In those days, I used UHT milk to prepare my own yogurt rather than trust the local manufacturing.
I’ve reproduced my instructions below. What I want to know is - how come I sterilized 5 yogurt jars but not the sixth?
I’m sure I had a reason at the time, but it has been about 10 years and I cannot for the life of my figure out why the process below makes any kind of sense.
Yogurt
[ol]
[li]Measure 800+ ml milk into saucepan and put over high heat.[/li][li]Sterilize for 15 min in 1 Tbs bleach/1 gallon water: large Tupperware measuring cup, large stainless steel spoon, 5 yogurt jars with lids, thermometer, strainer[/li][li]When milk rises to top, turn off heat.[/li][li]When timer goes off for sterilizing supplies, put thermometer into milk (if it seems to have cooled some).[/li][li]Take starter yogurt out of the refrigerator.[/li][li]Dry sterilized supplies and set jars in yogurt warmer. Put spoon and strainer into the Tupperware measuring cup and add the starter yogurt.[/li][li]Wash and dry the sixth yogurt jar very thoroughly, add to warmer.[/li][li]When thermometer reads just under 100 degrees F, pour milk through strainer and stir into starter yogurt.[/li][li]Pour milk and starter evenly into the six jars, screw on lids, and plug in yogurt warmer. Set time reminder for 4 hours (if using whole milk) or 6 hours (for skim).[/li][/ol]
I don’t have a better theory, so maybe. But I don’t think I made a point of setting aside a particular jar to use as the source of the next starter. (And if I needed to, I probably would have included it as part of my instructions.)
It’s perplexing, as my culinary memory is usually eerily good, but I am drawing a complete blank on why I would have done this odd thing.
ETA: On re-reading the instructions, I think you are on to something. It might not have had anything to do with the bleach, just the source of starter. If the starter came from one of the six jars, but could not be used until AFTER the sterilization process, then it stands to reason it would not have been included.
That whole sterilization process seems a bit over the top, though. Does everyone do that when they make yogurt? Or was I just absurdly paranoid?
When I first arrived in Egypt, I attended a health orientation session given by a nurse who told us that basically everything in Egypt was completely unsanitary. She recommended washing all produce with soap and letting it soak in water with bleach in it. Her rationale was that night soil is used in Egypt to fertilize.
I bought into that for a while, but as I actually developed a life in Egypt and didn’t have 5 hours/day available for the intense level of sanitation that was recommended, I relaxed a little. Subsequently, I learned that those recommendations were not official in any sense; it was just that particular (and possibly crazy) person’s view of how to stay healthy.
By the time we left, I was satisfied with ordinary washing under running water, peeling, and cooking as means to avoid contamination.
(The quality of the dairy products was another matter, though. Something like a third of the locally produced dairy failed quality tests for bacteria levels - I got that from a trusted NGO source that did a study using international standards, not an individual who may have had an axe to grind.)
I also use a crockpot and do not “sanitize” anything when making yogurt. If you are in a generally clean environment it should not be an issue. Obviously, though, when making yogurt, you are creating an environment specifically to grow bacteria. Any stray micro-organisms that are present will multiply along with the yogurt.
That is not surprising. It is incredibly easy to contaminate milk prior to bottling, that is why the US mandates pasteurization.
I used to make yogurt many years ago when it was far harder to buy. It was standard practice to sterilize the gear with dilute bleach so that the only organisms you cultured were the ones you deliberately introduced. Most older recipes would recommend this practice. I don’t think you sterilized the final jar because it is the starter you took from the fridge and its contents, in part, are in all the jars of yogurt. It hasn’t been sitting around out of the fridge since the last batch was made but the others were once emptied.
I’d guess you didn’t want to specifically NOT sterilize the final jar, it’s that you’ve just emptied it of yogurt, so you trust it doesn’t NEED to be sterilized. So you saved yourself a bit of work either sterilizing another jar that you just emptied, or transferring its contents to yet another container before starting so you could sterilize that jar.
Also, sterilizing the jars wouldn’t have anything to do with whether the milk has undesirable organisms or not.
I also used to homebrew, and there sanitizing/sterilizing was definitely a bigger deal. But that may just because it’s a longer process, and the price of ingredients is such that the time & effort required to reduce the contamination risk as low as possible is worth it, while throwing out a gallon of milk because your yogurt is funky isn’t worth the sanitizing steps.
The sterilization seems a little over the top to me, but maybe not with kids. When I was making yogurt regularly, my understanding was that if the wrong bacteria colonized the crop, the yogurt won’t set and you’ll know it’s a bad batch. I’m not sure where I got that idea though, and I probably wouldn’t count on it these days.
I think this is the likeliest answer. The sixth jar was still sitting in the fridge, full of starter, while you were sterilizing the others. Plus, you were deliberately inoculating the other jars with its contents; there doesn’t seem to be much point in sterilizing it when you were doing that, so you probably just washed it to get any gunky residue out before refilling it.
Mrs. FtG, before she went all vegan on me, used to maker her own yogurt using no special equipment. Did it all in one dutch oven. Heat it to kill extra bugs, let it cool enough, add starter, put in a pre-warmed (but off) oven with the light bulb on, wait overnight. Let Mr. FtG clean the pot.