Creative Ways to Use Leftover Whey

If you've made your own Greek yogurt, labneh, or other fresh cheese, you're left with a bunch of whey. This thin liquid that's leftover is from the coagulation of proteins and fats in milk and cream during the cheese-making process. But don't pour it down the drain! Whey is actually pretty useful stuff.

Farmer Cheese

First, determine which kind of whey you're working with. Sweet whey and acidic whey are byproducts of different dairy items and are good for different uses. As the name implies, acid whey (often a byproduct of homemade yogurt) is higher in acid and therefore has different applicability. It's also important to note whether you added salt to your dairy before straining. Salt in the whey may limit its use as well. 

Uses for Sweet, Unsalted Whey

Sweet whey is the whey that comes from things made with rennet, like most cheeses. Try these uses for the sweeter whey:

• Make ricotta: True ricotta cheese is made from the whey that's left over from making mozzarella and other fresh cheeses. To make ricotta, the whey is heated often with fresh milk and citric acid. Then the curds are harvested. 
• Form mozzarella: If you're making mozzarella, you must stretch the curds in hot water. You can use the whey instead of plain water for more flavor. 
• Make butter: To use whey to make butter, leave it to cool for a few hours or overnight. The cream present in whey will rise to the top and can be scooped away and used to make butter. 
• Pest control: Strain the whey well and dilute 1:1 with water. Spray on plants to help keep powdery mildew at bay.
• Amend soil acidity: If you're growing plants that need more acidity, like tomatoes, or if you want to turn your hydrangeas blue, bust out the whey. It will lower the pH of the soil.

Uses for Acidic, Unsalted Whey

Acid whey comes from products that have used bacterial action to acidify the food, like goat cheese, yogurt, sour cream, and labneh. Use acidic whey for these sorts of things:

• Smoothies and mixed drinks: Whey is full of probiotics and has a bracing acidity. It may not be palatable on its own, but try it in smoothies or even cocktails. Replace milk or juice in a mixed drink for a bit of creamy tang. Just be aware that whey does have lactose in it still, so if you're intolerant, steer clear. 
• Make lacto-fermented soda: A dash of whey can be used to make a refreshing, effervescent beverage. Simply combine whey with soda water and, if desired, simple syrup for sweetness.
• Kickstart lacto-fermentation: Since acid whey comes from lacto-fermented foods, it's already got a bunch of the good bacteria in it you need to get a good ferment. Add a tablespoon or two to a new ferment to get it bubbling for all sorts of veggies like cabbage, carrots, radishes, and more.
• Feed it to animals: This is an age-old practice in Emilia-Romagna. The whey from the production of Parmigiano Reggiano is fed to the pigs that ultimately become prosciutto. Don't have pigs? Add some to your dog's diet, or supplement feed for backyard chickens. 
• Add to your beauty regimen: The acidity of whey tones skin, so add it to your bath water or swab on with a cotton ball for dewy skin. 
• Condition your hair: If you're using an alkaline shampoo (such as the no-poo method), whey acts as a balancer, neutralizing the pH. Even with regular shampoos, rinsing your hair with whey can make it smoother and shinier. 

Uses for Salted Whey

Sometimes cheese recipes have you add salt before straining. This leaves leftover salted whey, which can be used for the following:

• Soup stock: Whey adds a deep flavor as a base in soups and stews, much like a stock. Replace part of the stock or water in a soup recipe with whey.
• Bake with it: The acidity of whey has a softening effect on glutenous bread and pizza dough. Some recipes even call for whey in the ingredient list. Adjust your salt in the recipe accordingly. 
• Soak nuts or grains: Why use water when you can soak nuts and grains in whey? It adds flavor and probiotics to the nuts or grains. Or replace some of the liquid with whey when cooking grains.