Yogurt - yucky, slimy texture

[soniaR]

I've been making yogurt for a few years and have been very happy with the results. Always 1% organic homogenized cow milk. As a starter, I have used either previous batch, yogurt culture, or storebought. I've never had a problem, nice separation of whey so good for straining for Greek yogurt.

My last batch was a disaster: the texture was, sorry to say, like slime. The yogurt dripped off the spoon in a weird way. Barely any visible whey. Edible but not what I like at all. I chalked it up to heating to 185F instead of my usual 165F never thinking that it might have been the storebought yogurt I got which was one I had never used before: 2% fat, all the correct live cultures, no additives, gums. etc. 

So when I made today's batch, using the same storebought yogurt (not wanting to use previous batch because it was so bad), it happened again!! Plus, by mistake I made a full gallon instead of my usual 1/2-3/4 gallon. So now I'm stuck with all this slimy yogurt that I don't like.

So here are my questions:
- Why would it take on this slimy texture?
- Is there anything I can do to this current batch to salvage it in some way, or at least camouflage the texture so I can eat it?(BTW, last batch I tried straining for Greek and it would not separate and drain.)

I'm assuming it was the starter yogurt, which I will never buy again. Everything else in my method was exactly as I have always done it.

Here is my normal method and the one I did today: Heat milk to 165F. Cool to 115F. Remove some milk to mix with starter yogurt, then mix into milk. Pour in jars and cover. Place in proofer at 120F for one hour; reduce to 86F. Time until ready always varies.

I want to emphasize again that the yogurt I've been making for two years with this method has had normal separation of whey; tipping a spoonful of it, it would fall off in a big clump rather than this drippy, slimy, stringy stuff. I'm not looking for a new method. I just want to understand what happened.

Thanks for any input.

[mikekchar]

Yep.  Totally normal for some yogurt cultures.  The slime is polysaccharides.  Some bacteria produces more than others.  Commercial yogurt producers often mix a high slime producer in for exactly the reason you describe: the whey doesn't separate.  They add extra milk protein (just skim milk powder, essentially) to make it super thick and creamy.  Because there are multiple cultures in the yogurt, they compete with each other.  So probably the slime producer likes the environment you give it.  It might also be stronger than the other cultures and when they make the yogurt initially, they put in less.  However, when you make the second generation, you have what remained in the culture, which might be mostly the slimy one.

It really is the case that each commercial yogurt uses different cultures, so if you liked your previous yogurt then you should try to start it with that one.  If you can't get it any more, it's time to start a search for a new favourite.

[soniaR]

Thank you. This really does explain it. I ate the rest of the small container of commercial yogurt I bought and it didn't strike me as gummy or slimy, but as you said, the slime culture in the yogurt I made liked the environment and took over. Next time, I will buy the yogurt I used to buy and make a SMALL batch to test it first just in case they changed their recipe. I sure learned this the hard way. I need to search for recipes to bake with all the slimy yogurt I now have!

[awakephd]

The very best starter yogurt that I have used is Fage whole-milk Greek yogurt. Makes an absolutely delicious yogurt!

[River Bottom Farm]

Slimy yogurt goes well in smoothies. Just blens itbup with some fruit and a little honey.

[soniaR]

I thought I'd give an update on my slimy yogurt dilemma. Since my OP, I have made four more batches of yogurt, each with a new brand of yogurt (again, live cultures, no additives), including the brand I previously used for two years with success in getting a good separation of whey. All four resulted in slimy yogurt, although to varying degrees of sliminess. But still no separation of whey. I've learned to tolerate it and none has gone to waste. But I just can't figure out what's going on. I ferment the yogurt in a bread proofer that I use frequently for starter and dough, but the yogurt is in jars with tight fitting lids so I don't think anything in the air can be getting in. I miss being able to strain my yogurt!

[Susan38]

Hi!  I've been making yogurt weekly for about 5 years now, mostly from fresh Jersey/Brown Swiss milk but also from store bought Straus milk  (pasteurized, non-homogenized) and I use New England Cheesemaking's Y5 Sweet Yogurt culture.   Most of the time the yogurt turns out thick, without the whey separating out.  I would not call it slimy, it is very thick and good.   Even though the whey does not readily separate out in the jar, it will strain out using a Greek yogurt strainer or muslin or similar and it tastes great so I am very happy with it.

But I do remember a few times when it would separate out into a more fragile "curd" and whey.  Most recently when this has happened, I sleuthed it out to be the variations in milk...different cows getting different feeds at different times, with widely variations in cream content. I don't think it was the culture as it's the same one I've been using for years, although I suppose it could be suspected  since there have been different batches used.  Anyway, I don't recall the separation happening with the Straus milk, but since I am now using it (Straus) again, I will report back if I ever get the separation with it.

You said you're using the same milk, but is it possible there have been changes to the company's processing methods that could be causing your yogurt changes?

Your post also brings back to mind an article I read awhile back in New England's blog about an experienced cheese maker suddenly having trouble making cheese.  She made the same cheese every week for years (I can't remember what kind) when suddenly she was having aging failures.  She first suspected her milk, but was able to rule that out.  Finally she realized her daughter was doing a lot of baking with sourdough starters and such, and suspected yeast contamination from the air.  I guess it is possible to have a healthy population of yeast in the air when you are doing a lot of frequent baking with yeast and starters.  I can't remember if she then tried a batch of cheese in a different location, or if she thoroughly scrubbed her kitchen and didn't bake in it for awhile, but either way, her cheeses turned out to be successful after that.  So it turned out to be yeast contamination after all.  Since you said you are doing a lot of baking, I wonder if that could be the issue with your yogurt?  I understand you are proofing in sealed containers, but the yeast could be getting into the milk while you are heating and cooling it?

If none of the above are the cause, I think you have quite a mystery on your hands!  Let us know when you figure it out, and most importantly, don't give up!

[mikekchar]

Slime in yogurt is usually the bacteria producing polysaccharides (which is a fancy way of saying "complicated sugars" that aren't actually sweet).  If you are producing the same slime from different starters, it means that you have another bacteria present that's generating the slime.  Since you are using pasteurised milk, it's not coming from there, so the only place left is your equipment.  To solve the problem you will have to disinfect all of the things that your yogurt is exposed to.  To be fair, you should be doing that anyway, but you can get away with not doing it for a surprisingly long time (often years or decades) without running into a problem.  Once you get the appropriate colony established, it can be a bear to get rid of.

Before you make yogurt, boil your jars and the lids.  If you are heating the milk in a pot, boil some water in the bot before you start.  Put your temperature probe in the boiling water to disinfect it.  Boil the spoon you are going to use to measure out the yogurt too.  For your milk, only use *new* unopened milk.  Don't use the dregs of a jug or something like that.  Open the lid (or carton) from a new container and use it right away.  Similarly, with the yogurt you use as a starter, use a new unopened container.

This should fix your problem.  If not then you have to think hard about where the rogue bacteria is coming from and try to get rid of it.  Sometimes it can be tricky and the only solution is to replace your lids, jars, etc.

[soniaR]

Thank you both for your helpful answers. I guess it's possible there are sourdough spores in the air that could be affecting the yogurt since I bake bread at least once a week. I'm not sure how to change that (only one kitchen!) but I for sure am going to try the other suggestions: sanitize all equipment and jars (guilty of not doing that ever for yogurt!); only unopened milk and culture (guilty of finishing off  the current 1/2 gallon before opening the new one; and short of hosing down my kitchen, I will at least try to make yogurt on a day far from when I last baked to minimize what's in the air.

I've come to learn that everyone likes a different style of yogurt. My "failures" range from super slimy to minimally slimy which some might call creamy which could to some be desirable (no separation). Whatever the level I get, if I were to strain, the glob of yogurt would just sit there. My preferred yogurt is none of the above, but one with clear whey and somewhat of a very light break.

By the way, I do use Straus for cheese but not for yogurt as I prefer lower fat. I use organic, either Clover in cartons or Trader Joe's in plastic.

I will attempt another batch after Thanksgiving and will report the results.

[Susan38]

A few notes--

In my area, with Straus I can get whole, 2%, and nonfat milks, and "whipping cream" (as well as other milk products).

When draining my non-separated yogurt, I put it in the draining container frig for a few hours and the whey drains out...leaving it for 24 hours results in a nice yogurt cheese.  I'm curious that your "slimy yogurt" does not separate out at all, even over time?

I found on the internet that some yogurt makers are attributing "slimy yogurt" with yeast contamination, among other causes.  Of course, with the internet one has to sort fact from fiction so I don't know if it's true or not, or if, like Mike is saying, it's strictly related to polysaccharides.

Good Luck with your next batch!  Happy Thanksgiving!
 

[soniaR]

I'm glad to say my yogurt isn't slimy any more and I no longer have six-inch drips hanging off the side of the spoon! It's still creamier than it used to be. I'm sure some people prefer it that way! I've come to appreciate it more. I can drain it if I want, but I'm sticking with non-Greek style for the time being.

When it was truly slimy, it did not drain at all and totally stuck to the coffee filter I use to drain. It was a mess. I gave up. Thankfully, things are better now even if I don't know why. I'm careful to sanitize the thermometer when making yogurt since I also use it for sourdough starters and dough. I always washed it but maybe that wasn't enough. And I sanitized the proofer I use for yogurt, even though the jars tightly covered. I was not in the habit of taking the same sanitizing precautions with yogurt as I do for cheese.

I do see that Straus has 2% milk (and other products). I was so focused on the 1-gallon whole milk that I didn't see the others. Good to know. Thanks!

[mikekchar]

I'm glad to hear that it's all sorted out now :-)  It's pretty darn easy for your house flora and fauna to assert itself on your carefully controlled milk rotting :-)  Bacteria is microscopic and you only need a tiny amount to throw things off.  Washing is definitely not enough if you have a really assertive bacteria living in your house.  It's kind of frustrating because you will hear all sorts of people who say, "I've been doing this for decades and I never clean anything.  It's never a problem for *me*!"  It can lead you into a fall sense of security because *at the moment* nothing that is really intrusive happens to be growing in your vicinity.  But once it sets up shop, you'll never get rid of it, so it's best to always sanitise as best you can when doing these things.  I even do it it for jam making!

[Susan38]

Hi again and I'm so glad you are having better success these days!  I have to say, since your posts last fall I have been scrutinizing my yogurt texture more than I had in the past!  These days I'm using the 2% Straus milk with the usual direct set NEC Sweet Yogurt culture, making a half gallon every other week.  Most times it is coming out thick and creamy (not gobby drippy slimy), but a month or so ago I had a couple of batches where the whey was readily separating out! (I thought of you when that happened, ha ha!)  Not sure what caused the difference since all the ingredients and methods are continually replicated, but now I'm back to the thick and creamy type again.