The Greek yogurt market grew by 2,500 percent in the five-year period from 2006 to 2011. This type of yogurt had long been shunned by Americans as too thick and too sour, but it became a hot “new” product as consumers concerned about getting more protein and less sugar in their diets jumped on the bandwagon.
Although Greek yogurt’s growth has since slowed, it still constitutes a significant portion of the overall yogurt market, and remains popular with consumers—and yogurt makers still have to deal with a byproduct of making Greek yogurt: acid whey.
Acid whey is the whey strained off of Greek yogurt during production. Greek yogurt is thicker precisely because the whey is strained off. Acid whey is named as such to differentiate it from the sweet whey that’s a byproduct of cheesemaking.
“Acid whey is not new, but the explosion in the popularity of Greek yogurt has brought it to the forefront,” says Dean Sommer (pictured above), senior food and cheese technologist and a member of the management team at the University of Wisconsin-Madison Center for Dairy Research.
Whey is commonly used in many food products as a thickening agent, and in protein shakes and bars, but acid whey’s higher acidity and other properties disqualify it for these uses. Instead, it’s mostly spread on farm fields as fertilizer.
But as the quantity of acid whey being produced grows, this usage may become unsustainable, and Greek yogurt makers also have to pay farmers to take it off their hands.
Now, Sommer and others at the Center for Dairy Research have developed technology to make whey protein usable again.
Sweet whey goes through a drying process, but “if you try to dry acid whey, it turns into a sticky, gooey mess,” says Sommer. “So we had to come up with some new techniques.”
The technology—which Sommer’s team makes available to U.S. companies at no charge—uses a membrane processing system to filter acid whey into its various components, which individually can be used for different purposes.
The membranes are commercially available—for example, they are also used in processing sweet whey to concentrate the protein. The proprietary technology developed by Sommer’s team specifies the exact sizes of membranes to be used and in what order.
The new method filters out the protein, which is used in the same types of ways as protein from sweet whey; calcium, which can be used in supplements or added to drinks like orange juice; peptides, which are used in muscle-building supplements and also skincare products; and lactic acid, which is used by the food industry for brines and pickling solutions.
Sommer says there has been plenty of interest already from yogurt makers. “Instead of spending money for somebody to take care of their acid whey,” he says, “now they’re able to sell it.”