Written by: Sarah Novak | October 29, 2019
Being born and raised in Wisconsin, you can bet that I’ve had my fair share of cheese. Even now, living in Arlington, Va., I still put cheese on almost everything. So, when National Cheese Month comes around in October, I get very excited. In fact, I was in Wisconsin last week to visit several American Feed Industry Association members and had a few squeaky cheese curds (along with a brat and a beer).
One of the things a lot of cheese lovers may not know is that when you are making cheese, there is a very important co-product created that is very valuable to the animal food industry, called whey. Let me take a step back and explain the process.
Milk contains two types of proteins – casein and whey. In most cheese factories, milk is poured into big vats and a “starter culture” of bacteria is added to convert the lactose – or milk sugars - into lactic acid. Then an enzyme called rennet is added to “curdle” the milk casein. Once the casein has curdled, whey is left behind as a thin, watery liquid. Think about the old nursery rhyme – Little Miss Muffet sat on a tuffet, eating her curds and whey.
The whey is removed, salt is added, curds are cut into smaller pieces and then heated to release more whey. The additional whey is drained off, which leaves the clumps or casein (or curds). These clumps are pressed together and left to age (dry) for various periods of time.
Typically, for every 1 pound of cheese there are 9 pounds of liquid whey! So, what is done with the whey? According to the Journal of Dairy Science:
“Whey is a highly nutritious by product of the cheese industry which can be utilized well when fed to animals in a variety of forms such as liquid whey, condensed whey, dried whey, or as dried whey products.”
Sweet whey, the type of whey that is produced during the manufacture of rennet types of hard cheeses like cheddar and swiss, starts out at approximately 6 to 8% solids, of which on a dry matter basis is 11% protein and 70% lactose and the remainder is minerals. Ingredient processors can take the sweet whey and dry process it through various filtration to create whey protein concentrate, which can be used in calf milk replacers and whey permeate, which is also a good source of energy for dairy and swine diets. In addition, during cheese production, scraps of cheese that can’t be used for you and me will sometimes be used to feed animals as well!
Needless to say, every time you take a bit of cheese, remember that the co-product of whey is feeding a calf, pig or cow! As a Wisconsinite at heart, I am proud to say that not an ounce goes to waste.