Why You Should Be Souring Your Milk (on Purpose)

September  9, 2017

When milk’s involved, magic happens. We’re partnering with Milk Life to learn all about the essential role the farm-fresh beverage plays in elevating everyday recipes—and sharing recipes, tools, and tips for incorporating milk’s rich and smooth texture into wholesome at-home cooking. Read up here.

My mother is an excellent storyteller, and some of her best are about her grandmother, who was, as far as I can tell, a truly fierce and hilarious character. She could make anything out of anything, my mother says, true to her Italian roots. Once my uncles caught a slimy, writhing eel while fishing and brought it home in a cooler with great plans to scare Grandma Mary—who peered under the cooler’s lid, took one look at the creature, and exclaimed, joyfully, that she could cook that. So there.

All the trappings for freshly-made, creamy ricotta. Photo by Bobbi Lin

A great believer in “waste not,” she also made her own cheese. I do this too; knowing that the milk I buy at the store is heated to kill bacteria that can contaminate milk. This process, pasteurization, eliminates that bacteria, which lets babies and immunosuppressed folks and the rest of us drink milk without worry (and allows it a much longer shelf life).

You can sour pasteurized milk purposefully with some acid, either lemon juice or white wine vinegar. It’s kind of an amazing process to watch—science!—which is reason enough to make it yourself, even though ricotta (like queso fresco, paneer, and cottage cheese) is so commercially available. If you need more convincing: When these dairy products are made at home, they are really incredibly fresh-tasting, sweet, and creamy, and it’s hard to find anything quite like them at a store.

To make ricotta, you’ll need about 3 tablespoons of lemon juice or white wine vinegar for every quart of whole milk, plus a teaspoon of kosher salt. Heat the milk over medium-high heat with the salt until it’s steamy and the surface is murmuring, then take it off the heat, stir in the lemon juice, and let it sit for 5 or so minutes. This is when the action happens! In seconds, the combined force of the acid and the heat (with additional help from any salt you might add) curdles the milk, forcing apart the milk’s solid curds from its liquid whey. (Stirring gently will encourage larger curds; let it do its thing alone and the curds will be finer.)

These four cheeses were made of the same ingredients. Cool, huh? Photo by Bobbi Lin

Pour the mixture into cheesecloth or a thin, clean dishtowel set over a colander that's set over a mixing bowl and strain until you’ve got the texture you’re hoping for—shorter, 45 minutes to an hour, for a softer ricotta (good for spreading on toast) and longer, 2 to 3 hours or longer, for a firmer one (good for making stuffed pastas!). The yellowy liquid that’s left in the bowl is the whey, and you should hold onto it! Use it to make bread or crackers, or cook polenta or beans with it, or add it to a smoothie. Here are a few more ideas for using it up!

Photo by Bobbi Lin; design by Tim McSweeney

Ricotta’s not the only cheese that’s made this way. Paneer is almost exactly the same, but the milk is left over the stove’s flame while you add the lemon juice—encouraging larger, firmer curds, as opposed to ricotta’s small and soft ones, Then, the curds are thoroughly rinsed, wrapped in a cheesecloth, drained, and then flattened with a weight for 2 or so hours.

Shop the Story

Queso fresco follow a similar trajectory: White vinegar rather than lemon juice is added to the milk (still over the flame), with more salt than you’d use for paneer or ricotta. The resulting curds are strained through cheesecloth, then formed into a disc and pressed with a weight.

But cottage cheese, which may seem the most similar to ricotta at first, is also the most different: It follows the same basic heat-add acid-curdle-strain-rinse process, but you generally begin with fat free milk, mush the curds into a ball, then break up that ball into smaller curds and fold them into heavy cream seasoned with salt. You can make cottage cheese with vinegar, but rennet is the traditional curdling agent.

When these dairy products are made at home, they are really incredibly fresh-tasting, sweet, and creamy, and it’s hard to find anything quite like them at a store.

One final quick disclaimer for ricotta hair-splitters out there: Ricotta is the ultimate no-waste product, itself traditionally being made from a waste product. I’m not talking about sour milk here but about the whey leftover from cheesemaking. Ricotta historically is made from the liquid that remains after making mozzarella. (You can’t make more ricotta, alas, from the whey left after making ricotta—unlike other forms of cheesemaking, ricotta-making pulls most of the casein, which is what makes the creamy curds, out of the milk, leaving little left in the whey for a second round of cheese.) Since most of us don’t have regular access to that whey, intentionally-soured whole milk is a pretty good alternative, though it’s not the same.

A few recipes to use it (and the whey) in:

Make magic with milk this fall. We're partnering with Milk Life to learn all about milk and the incredible things cows can do—and arming you with recipes, tools, and tips for making use of milk’s superpowers while we’re at it. Have a look at just how essential its seat at the table is here.

See what other Food52 readers are saying.

  • Saira Bilal
    Saira Bilal
  • Judy Kaiser
    Judy Kaiser
Writing and cooking in Brooklyn.


Saira B. August 30, 2019
I came here to look for used of milk that was left out without anything added and in morning its kind of curdy
I don't know if its good or bad ,should i use it if yes then how ?
Judy K. September 27, 2017
Do you have a video showing how to make the different cheeses described in this article?