Yogurt-making @ home

[Fat Guy]

How do they actually make yogurt in a commercial setting? Do they make it in the individual containers, or do they make it in a big vat and then pipe it in?

[balmagowry]

How do they actually make yogurt in a commercial setting? Do they make it in the individual containers, or do they make it in a big vat and then pipe it in?

Just what I was wondering. I'm convinced they must make it in the container, because of the way it "sets" in that shape. But that is also a more perfectly controlled environment. Of course, my pilot light is perfectly consistent, so I have a pretty controlled environment myself. Guess I was just having just one of those not-very-logical nervous-nellie qualms. I shall suppress it in future.

[Fat Guy]

* Whey production can be kept to a minimum by making sure the milk is brought right to the boil.

Interesting. Do you have any idea why this is?

[Jensen]

* Whey production can be kept to a minimum by making sure the milk is brought right to the boil.

Interesting. Do you have any idea why this is?

Not a clue. It was just something I read on a yogurt-making website somewhere and decided to try it out. So, rather than use my thermometer, I went just by visual cues and the yogurt was a better consistency. Much less whey...

I'll see if I can find the website again. It might have explained it and I just didn't retain that information.

[balmagowry]

So, Jensen (or anyone else who might know...!), that brings me back to the covering question: when you use the plastic container to incubate, do you cover it with its own lid? or something looser? I seem to remember that the little glasses in the Salton jobbie had snug-fitting plastic caps - but I don't remember whether they were supposed to be in place during the process or got put on afterward.

Edited March 29, 2004 by balmagowry (log)

[Jensen]

So, Jensen (or anyone else who might know...!), that brings me back to the covering question: when you use the plastic container to incubate, do you cover it with its own lid? or something looser?

Oops ... sorry, didn't mean to avoid that part of the discussion.

I've never had call to use one of the store-bought containers. I'm the only one who eats yogurt (well, the Spawn will eat it but only if it contains copious amounts of sugar) so I only make one batch at a time. Because of that, the container that came with the yogurt maker is always available.

All that being said, I don't see why you wouldn't use the container's own lid.

[ellencho]

I'm a bit unclear on the types of yogurt that you are all making. Is it more of an American-style yogurt or a Greek yogurt? And what are the variables that you need to change to make one or the other?

[Jensen]

I'll see if I can find the website again. It might have explained it and I just didn't retain that information.

I can't believe I found it again! I did learn an important lesson in finding sites though ... if you remember the original search terms you used to find it in the first place, chances are much higher that you'll be able to find it again. In this case, the key phrase was "bulgaricus"...

At any rate, this is the site that mentioned bringing the milk up to a boil will help lessen whey production: click here

Ellen: I'm making a European style yogurt. According to a couple of different sources (including the link above), the difference in method is the addition of dry milk powder. I'm guessing that would increase the protein content in the mixture and lead to a firmer end product.

(But don't quote me on that...it's really just a guess )

[balmagowry]

Sigh. I need to revisit some of this tereritory in light of more recent results. Let's see; I logged my first, semi-disastrous batch, and my second, magnificent batch. I'm now eating the third batch, which has also been excellent, though a little different, and I want to compare notes on the differences.

Both batches were cooked and mixed and incubated as nearly identically as possible, as regards method, time and temperature. Both used fresh Dannon yogurt as starter, same proportions. Both incubated in oven with pilot light.

First batch was made with 1/2 gallon whole milk and was incubated in large pyrex bowl loosely covered with cloth, then decanted into quart containers for storage and use.

Second batch was made with 1% milk and was incubated in the quart containers themselves, with their lids on tight.

Those are the only differences I can think of. In both cases I brought the milk to a boil, then cooled it to about 110* (did the "finger test" too), whisked in the starter, set it to incubate.

Both batches were smooth and had excellent flavor (I got an idiotic degree of pleasure from the way the second batch looked in its containers - all smooth and professional...). The first batch formed virtually no whey. The second didn't form any either until I started using it - after I'd taken out a serving, the next time I opened it there was a small puddle of whey. Pretty much exactly what you see with commercial no-fat yogurt - I don't remember whether commercial full-fat does the same.

Also, the first batch stayed smooth and creamy throughout. With the second batch, I found that as I got to the bottom of the first quart the mouth-feel changed and became almost a little bit grainy. Top of second quart has been smooth so far; I haven't cheated yet and delved to the bottom because I don't know whether it would skew the result; but of course before I reach the bottom of this quart I want to have a plan of action for the next batch!

I had intended to start using my own yogurt as starter, but I think now that I'm not there yet, not until I answer these two questions.

I'm not actually unhappy with the whey - it's no more than I'm used to in commercial yogurt (and no more than my dog can happily manage with his morning kibble), but I would really like to understand what's going on there. I know we learned up-thread that bringing the milk to the boil is what suppresses whey production; but my gut feeling is that the difference between 1% and full-fat can't be a coincidence. As for the slightly grainy quality of the bottom of the second batch, I am wondering whether it has anything to do with incubating in the containers, and/or with sealing them during the process, since whatever it is presumably settled to the bottom before the yogurt "set."

Thoughts? Sorry to keep beating a dead horse, but if anyone can breathe a little more life into it it's you guys! Any insights will be appreciated.

[Jensen]

You've moved beyond my knowledge of the subject ... I have no idea.

[balmagowry]

You've moved beyond my knowledge of the subject ... I have no idea.

Dang, and you were my last best hope, especially after that masterly stroke with pulling the URL out of a hat!

[Jensen]

You've moved beyond my knowledge of the subject ... I have no idea.

Dang, and you were my last best hope, especially after that masterly stroke with pulling the URL out of a hat!

Well, never say never ... I did wander off to google to see if I could find anything out. And guess what? I found a cool report on a project studying the Effect of Milk Composition on the Quality of Fresh Fermented Dairy Products.

As far as the whey production goes, this bit is particularly interesting:

Increasing protein and fat contents in the milks resulted in increased gel firmness and viscosity, while decreasing the ratio of casein-to-whey protein in the milks resulted in increased viscosity, and decreased levels of syneresis. Decreasing this ratio lead to more rapid pH development in the yogurts.

According to the report summary, syneresis "refers to the tendency of the yogurt to whey-off during storage". So, increasing the fat content would result in less production of whey.

And now I'm off to read the entire report ...

[Jensen]

And one more cool site about yogurt production, protein:whey ratios, and even electron microscopy images of yogurt.

The link to "Grittiness" deals with spreadable cheese curd but it might also apply to yogurt. If the grittiness is caused by "protein clumps", perhaps holding the milk at the "just at a boil" stage for a while might deal with it?

[balmagowry]

Cool - thank you! Yes, I did some googling too, and while I didn't find anything as precisely to the point as those two discoveries of yours (have yet to read the grittiness link but I'm sure it will prove relevant), I did accumulate some ideas that made sense. First of all, I'm glad to have confirmation of the ratio of fat content to whey production - that's consistent, as it were, with several vaguer statements to the effect that full milk produces a "richer" yogurt (duh). Saw a lot of emphasis on cleanliness - or even sterility - of the containers; while I can see where taking this to fanatical levels might be too much of a good thing, still it wouldn't hurt me to be a little more careful about making sure they're really clean.... Also, everyone seems to make a big deal of rapid cooling after the milk has been heated. Fair enough - I can do that.

Learned some more about the possible effects of over-setting - most of the sources I looked at said 4-6 hours should be enough.

Curiously, the one point on which there was strong disagreement is the one about boiling the milk - I've seen everything from "do NOT allow it to come to a boil" through "bring to the boil and take it off immediately" to "bring to a boil and continue boiling 2 minutes." Hmph. Well, experience has convinced me of the good effects of the second approach, so I'm not going to mess with that. And I'm satisfied about the whey. So I shall read your reports closely, and shall also look to cleanliness and cooling by way of improving my general practices. And... we'll see.

[Jensen]

I would think running the containers through the dishwasher would get you pretty darn close to sterile (at least, that's what I keep telling myself).

Also, an ice water bath cools the milk quite quickly.

I've seen the same variation in the answers to the "boil the milk" question and my experience is the same as yours...the best results seem to come about when the milk is brought to a boil (but not much beyond it).

Do you have a temperature probe and a hold function on your microwave? I wonder if using those two features for heating the milk in the microwave and holding it at 100 degrees or so (Celsius or whatever it is in Fahrenheit ... my "bilingualism" in measures escapes me at the moment) would have any affect.

Quick, someone with that sort of microwave ... go make some yogurt!

[balmagowry]

It won't be me! I used to have a probe, but no more. Actually, though, I'm pretty happy with the incubation temperature, based on results. I do want to use the cooling bath, though. Oh! forgot to mention that I'd also seen a lot of emphasis on pre-warming the containers and the starter yogurt. Wonder how much that actually matters. Getting back to the cooling stage, though, it comes back to me now that that was another difference between the two batches - in each case I'd poured the milk off into a bowl to cool, but second time around I used a taller, deeper one, and the cooling took a good bit longer - 10-15 minutes more. Sounds like that may be important.

Meanwhile, I've just been and gone and read those reports and sort of more or less understood some of 'em. I was especially interested in the grittiness thing, and I do think it's sort of relevant even though the conditions for cheese spread are obviously different. The upshot seemed to be that the gritty particles formed when the milk hadn't been heated enough, or for long enough. And the report did say that a lot of what they did with cheese had been learned from working with yogurt. On the face of it, this is certainly yet another argument in favor of bringing the milk to the boil - maybe it means I should try the boil-2-minutes method. I guess it's worth a shot.

I'm not too worried about sterilizing. I'm not sure, though, that I did more than a cursory hand-washing this last time around; I was in a hurry. Hmmmmm.

Oh - one other dichotomy, though not apparently relevant to the present question - the one between whisking the mixture thoroughly and stirring it gently for fear that too much exposure to air will damage the bacteria. Doesn't seem to have done so in my case, but I wonder where they get these ideas....

[fifi]

Sigh...

All of the above seems to confirm my Rules according to Mother.

[maxmillan]

I recently purchased a 1 litre Salton yogurt maker and have had some hit and misses with it.

I don't like the tartness and sweeten it with frozen berries and maple syrup. Also, I find it too thin so I bought some agar which I will try soon.

I've tried organic whole milk, 2 percent, 1 percent and skim milk. Each time I used a purchased organic yogurt for the culture.

Why is Europe's yogurt so much more creamier and less tart?

I want to make yogurt with soya milk and other alternatives to milk. I've bought live culture and have yet to make it because I don't know how to start. I like to make it creamier and less tart. My concern is to control the sugar, fat content is the least of my worry.

Any suggestions or help? Thanks!

[balmagowry]

The link to "Grittiness" deals with spreadable cheese curd but it might also apply to yogurt. If the grittiness is caused by "protein clumps", perhaps holding the milk at the "just at a boil" stage for a while might deal with it?

A clue! Finished the second quart yesterday, and found it even more "grainy" at bottom than the first - "grainy" being an inaccurate way of describing what were really tiny bits of firmer curd. Anyway, scraping the bottom, I began coming up with a few larger bits of - well, at first I thought they were soggy paper, but of course they were made of curd and were edible, and it suddenly hit me: I bet the cooling milk formed a skin, and I bet I forgot to take it off before whisking in the starter. I'm starting fresh today, so will prove the pudding a few days hence; but I'm betting, and hoping, that this is the answer.

[Jensen]

I just dumped my last batch out ... I made it before my trip to the spa and so what was left was over 10 days old. I found that there was some definite "cheese-like" substances down at the bottom of the container. Naturally, I thought of you ...

I wonder if some of the larger protein clumps precipitate out, settle to the bottom, and continue to "clump up". I know I don't have the skin problem as, when I put my pot in the ice water bath for cooling, I stir it frequently. (I'm impatient and I know that stirring something will help it cool faster.)

There is always the possibility that some of the culture remains active at lower temperatures and the acidification of the product continues at a slower rate. In my readings on yogurt (btw, great article in the SF Chronicle about yogurt), I seem to recall that there are more than just L. bulgaris and S. whateveris in most yogurts; however, only those two are required to be in it. Maybe the continued culturing is a byproduct of another bacteria???

I'll be starting my new batch today too (after brunch and the Woody Guthrie review in Nevada City!).

[Jensen]

I don't like the tartness and sweeten it with frozen berries and maple syrup. Also, I find it too thin so I bought some agar which I will try soon.

I've tried organic whole milk, 2 percent, 1 percent and skim milk. Each time I used a purchased organic yogurt for the culture.

Why is Europe's yogurt so much more creamier and less tart?

I posted further up in this thread about various things I've found out in my yogurt-making adventures. There are lots of interesting tidbits posted by many yogurt-making people in this thread; check 'em out!

Tartness is dictated by how long you allow the culture to incubate. It seems to me that the Salton maker (which I also use) recommends a long time for incubation. Cut that back to 4 to 6 hours.

Creaminess is due to fat content. Use whole milk.

You might want to consider straining your end product instead of using agar. This is probably just a personal bugaboo for me but, as my educational background includes undergraduate studies in Microbiology, I can't help but associate agar with culturing bacteria in petri dishes. Blech...

[balmagowry]

I just dumped my last batch out ... I made it before my trip to the spa and so what was left was over 10 days old. I found that there was some definite "cheese-like" substances down at the bottom of the container. Naturally, I thought of you ...

I wonder if some of the larger protein clumps precipitate out, settle to the bottom, and continue to "clump up". I know I don't have the skin problem as, when I put my pot in the ice water bath for cooling, I stir it frequently. (I'm impatient and I know that stirring something will help it cool faster.)

There is always the possibility that some of the culture remains active at lower temperatures and the acidification of the product continues at a slower rate. In my readings on yogurt (btw, great article in the SF Chronicle about yogurt), I seem to recall that there are more than just L. bulgaris and S. whateveris in most yogurts; however, only those two are required to be in it. Maybe the continued culturing is a byproduct of another bacteria???

Thanks for the link! Did you notice this, at the end of the rundown of yogurts?

Total. Whole cow's-milk yogurt contains live cultures and added cream; mild, sweet, creamy and very thick, like strained yogurt (lebni); excellent for salads and cooking. Total sheep's-milk yogurt is even thicker but slightly grainy. Made in Greece.

Thicker but slightly grainy. Hmmmmm.

Your theorieas are certainly plausible, especially as regards additional bacteria (l. acidophilus foremost among them). But - if that is the case, then why doesn't the same thing happen in store-bought yogurt that features the same live cultures? If the same yogurt that I'm using for starter (Dannon, in both this case and the previous) doesn't behave that way itself, then it's hard for me to understand how its bacteria could be causing the phenomenon.

And I'm not happy to have my comforting milk-skin theory shot down.

Well, IAC, I'm going back to whole millk with today's batch - will also hit the local health-food store to see what kind of exciting choices they have by way of starter yogurts. I know it's unscientific to vary so many factors at once, but this isn't just science, it's breakfast - and I'm having fun.

Meanwhile, another vague query. I was toying with the idea of trying the powdered-milk thing. Mind you, I love the yogurt I've been making without it, but I thought it might be interesting to try a batch that way so I could compare them. So off I goes, the other day, and buys some powdered milk; only to come back and look more closely at the recipes that call for it, and find that they all say "non-instant." And of course what I got is instant, because it's the only thing they had at the market. So - is non-instant powdered milk about to become the next hard-to-find ingredient? What is the difference between instant and non? Where does one find non?

[memesuze]

Back in my yogurt-making days, I'd use non-instant from the local coop grocery, Wheatsville - you should be able to find it at Whole Paycheck or Trader Joe's or any other "natural" food store....It's interesting stuff, I recall it as being "squeaky" - the particles, that is, and they blew around as freely as other white powders....

[iguana]

Another possiblity that works well for incubation is to put a couple inches of water in a plastic picnic cooler and use an immersible aquarium heater to maintain temp. This gives you great temperature control-- important if you are going to get into home cheesemaking, etc. It's a bit of overkill for just a quart of yogurt, but is great for a couple gallons of developing curd. If you get sick of making yogurt, you can always get fish.

[Jensen]

QUOTE

Total. Whole cow's-milk yogurt contains live cultures and added cream; mild, sweet, creamy and very thick, like strained yogurt (lebni); excellent for salads and cooking. Total sheep's-milk yogurt is even thicker but slightly grainy. Made in Greece.

Thicker but slightly grainy. Hmmmmm.

Is that the same article that says sheep's milk has the highest amount of protein (when compared to cow's or goat's milk)? If so, then the graininess might be due to bigger protein lumps ... that, in turn, would suggest to me that one shouldn't add protein in the way of dry milk powder. Although it would give a firmer product, it might also exacerbate the grittiness problem.

My challenge for the day will be to make yogurt using starter that I saved from another batch and froze. I thawed it out yesterday and it looks like it separated in the process. I'm not terribly hopeful of success for this experiment but I'm going to try it anyway.

Will report back with results.