Raw milk yogurt turned into ... mozzarella?

[CathyWeeks]

I tried making raw milk yogurt today.

I heated it to 100 degrees, added the starter and left it in my yogurt maker for 6 hours.

Usually 6 hours in my yogurt maker is plenty of time. So when I opened it after that long and discovered my fresh whole milk was still.... fresh whole milk, I decided maybe it wasn't fresh enough (too much bacteria was competing?)

So I put it into a pan with the plan that I'd pasteurize it and start over. I proceeded to heat it up, but around the 130 degree mark it started to solidify into a rubbery stringy solid. It was very clearly turning into some sort of curd that was separating from whey. I actually tasted a tiny bit, and it tasted a little like fresh mozzarella.

What the heck was going on?

[CathyWeeks]

I should also mention that I was using the Y5 yogurt cultures from the New England Cheesemaking supply, and those packets say 6-12 hours. So I'm guessing my first batch could have been fine - and I just didn't leave it long enough. I've got a new batch going in the maker now, and I'm letting it go overnight this time.

[Tim Hall]

Cathy, it sounds like you in fact made cheese. Did you check to see if the first attempt at yogurt was at all sour, or did you go by the fact that it was not yet thickened?

The reason I ask is if the milk began to sour at least a little, the acidity (and possibly enzymes from the yogurt culture) probably caused the milk to curdle when heated. This is the basic process for making farmer's cheese. You can achieve the same thing by adding a little lemon juice or vinegar to milk and heat it.

[deuxetoiles]

Yogurt will not thicken unless the milk is first heated to the point where the proteins denature: 80 °C, 180°F.

So, you might have been growing a yogurt culture, but that alone wouldn't thicken it. Did you taste it? The culturing is what lends the sour taste.

I imagine you were, because the acidity seems to have been high enough to make the milk curdle when you heated it again. Nice trick! :)

[CathyWeeks]

Yogurt will not thicken unless the milk is first heated to the point where the proteins denature: 80 °C, 180°F.

So, you might have been growing a yogurt culture, but that alone wouldn't thicken it. Did you taste it? The culturing is what lends the sour taste.

I don't think the first part is correct, for a several reasons. Please bear with my long-winded explanations. :-)

1. I've made firm yogurts with pasteurized and ultrapasteurized milks, and if you look at the various commercial pasteurization processes, the milks are never raised to the 180 degree range, and I have never brought it up to that range myself, and my yogurts always firmed up just fine, easily as firm as grocery-store yogurt. When I've felt lazy, I've done it by throwing cold milk into my yogurt maker, stirring in the starter, and letting the yogurt maker slowly bring the milk up to temp. 4-6 hours later, I had firm yogurt.

2. The recomendation to heat it to 180 is usually accompanied by information about pasteurization - you want to kill off any competing bacteria so the yogurt cultures will proliferate without competition. My yogurt cookbook doesn't even mention the denaturing process as necessary - just that it pasteurizes it. Oddly, commercial pasteurization is done at much lower temps.

3. I've since successfully made raw-milk yogurt without heating it above 100-110 degrees. I did some reading online, and found that it simply takes a great deal longer - probably because of the competing bacteria issue. Instead of 6 hours, I have to incubate 20 hours. My reading online on other sources, suggests this time-length is typical. It does make a somewhat less firm yogurt, with more whey than grocery-store yogurt. I compensated for this by gently cutting the curd and then rubber banding butter muslin over the container, gently inverting on a dome-shaped metal mesh strainer, and letting the whey drip for an hour. It lost only a little volume (maybe 1 cup out of 1/2 gallon), and the texture was much closer to commercial yogurt, thicker even along the surface against the muslin (like Greek-style).

I imagine you were, because the acidity seems to have been high enough to make the milk curdle when you heated it again. Nice trick! :)

LOL. I discarded it, but now I wish I'd drained it and used it as mozzarella. It was indeed cheese. Even tasted like it.

[Rutabagagirl]

OMG!!! I remember trying to make raw milk 'sun yogurt' or maybe just raw milk yogurt (unheated) and it tasted like mozzarella! Weird!