Thursday, April 11, 2013

Making yogurt

If you'd have asked me a year ago if I'd ever make yogurt you might not have gotten a favorable response.  Not that I didn't like it then, it's just one of the weird things that I had never considered making.

Quart of yogurt at Aldi's is $2.  Tiny cup of it at Kwik Trip is $.79, half gallon of milk is about $1.50.

Of course, you either need some starter or some yogurt to make more I bought the $2 bucket to see if I'd use it all before it rotted.  Turns out that I did.  I used the last of it today to make a quart, I wonder how it'll turn out.

I did make some a week or so ago, it turned out pretty thin.  It had a decent flavor, for plain, but very thin.  After reading some pages on the interwebsnet thingy, I may have found out why...and if this batch turns out thin too, that will support my new found knowledge.

All pages concerning making yogurt are consistent with one thing:  being widely varied regarding the end temp to heat the milk...and I figgered:  the crap is already pasteurized, why do it again?

Here's the answer I got: (from here)

If you are using pasteurized milk, you must first sterilize it. Some people ask why this is necessary if the milk has already been pasteurized. The answer is that pasteurization kills the natural bacteria that are in milk, so as it ages, the milk can collect and nurture bad bacteria. If you simply warm the milk up to 110°, the bad bacteria can flourish and make the milk taste unpleasant or even make it harmful. (This is why pasteurized milk has an expiration date, and is not good to use after a certain time.)

Sterilizing the milk just before culturing it makes sure that the milk is completely clean and will present a welcoming environment where the yogurt culture can thrive and do its work. Additionally, heating the milk denatures (changes the characteristics of) the milk proteins, weakening the cell membranes and allowing the protein molecules to adhere to each other, causing better coagulation in the yogurt.

The first batch I made was from old, expired milk.  It didn't smell sour, but was nearly a week past the date on the bag.  Yes, people not familiar with Kwik Trip/Kwik Star, we buy milk in a half gallon sack.  It is quite a bit cheaper than those plastic jugs....and comes with a free pitcher.   They used to have a little bag corner slicer too, and we have one, but we just use a scissors now.  We fold the corner over and clamp it, even though the pitcher has a clamping slot machined/moulded in it already.  

You can see that I bought "Fit and Active" yogurt.  This is nonfat stuff and may be another reason mine turns out thin, even though I used whole milk.  More about the picture.  You can see the thermometer next to the crockpot (which we got as a wedding gift, 1994, for those keeping score).  Apparently yogurt yeastie beasties are pretty fussy about temps, they die about 118 and doze off under 90.  They don't completely go to sleep in the cold, which is why older yogurt tastes more tangy or sour than new/fresh yogurt.  

Why does yogurt taste tangy or sour?  I can answer that.  Oh, you want to know why yogurt doesn't make your lactose intolerance reaction react?  Same answer.

The beasties that the yogurt introduces into the milk eat the lactose (sugar) that is in the milk.  Or something like that.  Less sugars means more sour.

I may buy an "heirloom" starter which I can use over and over.  Most websites say that if you continue to just save back some yogurt as a starter after "several" cycles the beasties get tired/nonproductive.  Ungrateful little bastards, is what I say they are.

I poured some milk in a sauce pan, turned on the heat and put the thermometer probe in the pan.  I heated it to 120 or so, since it was before I read that linked page.  I filled the crockpot with hot water, and when the milk was down around 110 I tempered the left over yogurt in the bucket, then poured the milk into the bucket and all over the counter including my wallet, which was lying innocently on the countertop.  A quick rinse, a not so quick swab, and then poke a hole in the lid for the bucket.  Drop it into the hot water and monitor the temp for a while...when it got up to 115, pull it out of the water, when it dropped near 100, turn on the pot.  I let the beasties feast for about 6 hours, during that time I made a batch of bread and lunch.  

I like thicker yogurt, so I put a coffee filter in the colander, propped that on a bucket and dumped in the yogurt.  It's interesting how much whey comes out. Last time, it was white, and I fed it to the dog.  This time it is nearly colourless and I'll save it for making bread.  The dog loved it, btw.  

It's been draining about an hour, there's about an inch of whey in that bottom bucket.  I did stir/scrape the stuff around on the filter, had a taste, it is quite tangy and I think it will thicken nicely once in the fridge.  If it doesn't, I have some xanthan gum that will thicken it.  

One reason the first batch might not have gotten thick is the too much culture for the amount of milk, or not keeping it warm enough during the incubation stage.  I think I'll experiment by putting it in the cabinet above the fridge's pretty warm up there.

I am going to call this a success.  Stop by if you want to taste it.
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