This one goes out to the yogurt and paneer makers, having been prompted by an exchange over on Twitter with a friend who had questions after reading the last blog on ricotta. It illustrates really well the core of all dairy product making: acid management.
Twitter friend: I’ve done quite a few batches of “ricotta” using the whey from Greek style yoghurt (and maybe adding am extra liter of whole milk). That whey makes almost bypasses the need for any extra acid to be added. What do you think?
It’s very possible to make ricotta from whey without adding more acid, because the whey is already somewhat acidic. Exactly how acidic will vary from one type of yogurt or cheese to the next, and also how long it’s been sitting around (the sugars in the whey continue to get converted to acid over time).
The acidity of the whey actually matters quite a bit–if the whey is still relatively “sweet”, say ~6.4 pH (fresh milk is ~6.6), you’ll still need to add acid. As it drops, less acid will be needed. There’s a good outline here.
On the other hand, if the whey is TOO acidic, the remaining solids won’t really coagulate. This is why you won’t get satisfactory whey ricotta after making an acid-coagulated cheese (eg paneer)–because the whey is already too acidic. At best, you’ll get a sort of dairy sludge if you strain the whey through cheesecloth. I’ve done this, and made a cheese spread with it, but it’s very dense, not light and fluffy like good ricotta.
You can counteract the high acidity of whey by adding more fresh milk to the pot to get the overall acid level back up above 6.0. Recipes specifically written for whey ricotta pretty much always include this step prior to adding acid, though the amount of milk you’ll be told to use again varies widely–often a couple of cups (1/2 a liter) to a gallon (4 liters) of whey, up to 50% of the current volume of whey. That’s because the acidity of the whey you happen to have could fall within a very wide range, and they’re trying to make it foolproof for you.
All of this assumes your whey is somewhere near 6.0 pH. The more acid (lower pH) it gets, the more likely you’ll be adding whey to a pot of fresh milk rather than the other way around.
If you don’t happen to have a foodsafe pH meter (I don’t), you can gauge acid levels very roughly by taste (below is courtesy of cheesemaking.com):
- pH 6.2-6.5 the curds and whey should taste sweet like milk
- 5.8-5.7 the curds will still have a slight sweetness but nearing neutral*
- 5.5-5.4 they will taste neutral, neither sweet nor acid.
- 5.2-5.3 a slight acid tang develops
- 5.1-4.9 a definite acid tang
- 4.7-4.4 and below the taste begins to have the tang of a euro style yogurt
*Note that different milk types such as goat and sheep taste different, and typically not quite as sweet as cow, when they’re fresh. So you need to know what the fresh milk of the kind you’re using tasted like in order to use this as a guide.
You can also buy foodsafe pH strips from a variety of online sources including Amazon, and those are pretty easy to use. The most useful ones test for a relatively narrow pH band (say 7.0-4.0), mainly because the color guide they give you to compare the test strip against will show finer .x gradations.
None of this examination of pH levels is in any way REQUIRED to make whey ricotta, so definitely don’t let the preceding few paragraphs scare you off. Just find a whey ricotta recipe, add some milk unless the whey is already really cloudy, however much acid they tell you, and off you go.
But if you’ve attempted whey ricotta and you’re not getting satisfactory results, now you can make better guesses as to why.
Tangent alert!
Traditional Greek yogurt is made from sheep milk, not cow milk, and often isn’t strained at all.
How does it get so thick? Sheep milk has a lot more solids in it than cow milk does: more than twice the amount of fat (7+ % vs 3.25-3.5%), and nearly twice as much protein. With all those solids, it really doesn’t take much at all to get them to find each other and link up in a coagulated mass. You’ll find if you work with sheep milk that you’ll get nearly twice as much curd as you would with the same amount of cow milk.
And if you eat a whole pot of sheep yogurt for breakfast, you’re unlikely to need lunch. I speak from personal experience here.
Into The Curdverse 
