If you strain your homemade natural yoghurt to make it into thicker ‘Greek’-style yoghurt, you will find yourself with leftover whey.
This whey, which has a lot of the same properties as milk, and also contains the live yoghurt cultures, is not a waste product but a valuable resource in cooking. It will keep in the fridge for a while in the same way as milk.
I often strain our homemade yoghurt, as the strained yoghurt gives as many servings as the unstrained yoghurt (because you eat less) and the whey is useful for so many things. It’s almost magical that you use the milk to make yoghurt, and then get something like milk back again!
I find that yoghurt made with 2 litres of milk, strained overnight, gives almost exactly 1 litre of whey.
What to do with your Leftover Whey
Starting more yoghurt
First of all, the whey can be used as a starter for another batch of yoghurts. I find they don’t tend to set as well, or appear a bit ‘watery’ so I tend to use whey only for starting drinking yoghurts. This is a great use for the fruit-flavoured whey left over from straining fruit-flavoured yoghurts: use it to start a batch of fruit-flavoured drinking yoghurts.
In place of other dairy products in baked goods
Next, you can use leftover whey in place of milk in most cake and scone recipes. Being slightly acidic (like milk) the whey will react with raising agents (baking soda, baking powder) to raise your mixture. I do this all the time.
Whey is particularly successful in recipes which call for buttermilk.
I make these Buttermilk Scones with leftover whey most often. They are not the most flavourful, but they are supremely light and fluffy and doubling the recipe uses up most of my whey from a batch of yoghurts. Just replace the buttermilk with whey throughout the recipe.
Note that I even make the above scones using fruit-flavoured whey left over after straining fruit yoghurts. The scones taste faintly of the raspberry, peach, grenadine, or whatever you used, but are no worse for that!
I most often use up fruit-flavoured whey using this quick berry muffin recipe. I use the fruit-flavoured whey instead of the milk and reduce the sugar by one third because the whey already contains sugar. I use frozen fruit straight from the freezer – raspberry whey with frozen raspberries is perfect, but I often ‘mix and match’ any fruit whey, even peach, apricot, etc, with any cherry/berry fruit I have in the freezer. The muffins here are made with gorgeous pink raspberry whey and blueberries.
Our favourite waffle recipe uses whey and you can find it here: Farmstead Waffles using leftover whey.
I have also used whey in place of some of the milk or buttermilk in american-style (ie small and thick) pancakes with no problems.
I use both fruit-flavoured and natural whey in place of milk in this convenient Everyday Fruitcake Recipe.
As a drink and in smoothies
Finally, there is no reason at all you can’t drink whey, just as it is. For some reason this doesn’t appeal to my family, so another alternative is to use it as the liquid in a smoothie – where otherwise you’d use milk or yoghurt. Again, this is an excellent use for fruit-flavoured whey.