A trip through the dairy aisle reveals America’s latest culinary love story. In an aisle once dominated by palates oforYoplait and Dannon, Greek yogurt has become the norm. Names like Chobani have become yogurt celebrities, while old favorites have had to develop their own Greek yogurts to keep up in a revolution that occurred almost overnight.
Greek yogurt now accounts for over half of all yogurt sales, according to Nielsen consumer reports. Dairy companies are producing more Greek yogurt than ever before, meaning that those companies are also dealing with more of Greek yogurt’s byproduct–acid whey.
Acid whey is a translucent green liquid pulled from soft cheeses and yogurt when cultured and can be as diverse as the dairy products it comes from. While some acid whey–and its sweet whey counterpart from hard cheeses–might be mined for nutrients, Greek yogurt’s less nutritious acid whey is usually tossed aside, often sent to farms to feed livestock and be spread over fields as fertilizer. Like many similar by-products, acid whey must be disposed of carefully.
But acid whey might be more than just waste to spread over a farm field. According to Mike Molitor, a longtime member of the Wisconsin Center for Dairy Research staff, acid whey could be a valuable resource.
“I’ve been working with acid whey for every bit of 20 years,” Molitor said. “I think it’s a tremendous raw material.”
According to Molitor, the acid whey produced by Greek yogurt contains solids like lactic acid and calcium that could, theoretically, be taken out of the acid whey and used for other products from infant formulas to bolstered nutrition in everyday foods.
For more than 40 years now, factories have been extracting proteins from sweet whey, using it to make everything from bodybuilding protein powders to food for both people and animals. A lot of these whey products are actually shipped overseas, with Wisconsin being the United States’ leading exporter, according to the Wisconsin Department of Agriculture, Trade and Consumer Protection.
Yet, due to its nature, the acid whey produced by Greek yogurt is more difficult to work with. Greek yogurt’s acid whey contains notably less protein than sweet whey, whose protein is its most profitable product. Beyond that, Greek yogurt’s acid whey contains more of a solid called galactose, which causes the acid whey to break down into a sticky sludge when dried like other whey.
“It doesn’t contain as much residual protein … and it does contain a tremendous amount of galactose,” Molitor said. “So the options to process it are more limited than the other kinds of acid whey.”
The Center for Dairy Research has been working on a way to dissect acid whey’s translucent gold. According to Molitor, acid whey is an ideal candidate for filtration. By running it through series of increasingly advanced and effective filters, researchers at CDR split apart Greek yogurt’s acid whey and isolate and concentrate its hidden treasures, like lactose and calcium.
According to CDR representative Bekah McBride, the CDR is exploring nanofilters - also known as nanofiltration membranes–which could better fractionate acid whey. By more accurately fractionating the whey, new doors could open for the maligned by-product.
“As you fractionate and concentrate different components, it turns up new applications,” Molitor said of the process. Those possible applications could range from lactose for infants’ formula and weening livestock, to natural calcium that could be pumped right back into the dairy products.
“While filtration techniques like the ones used by CDR are already mining acid whey from products like cottage and cream cheese in factories, increasingly more advanced and efficient nanofilter technology could mean that, one day, it wouldn’t be out of the question to see this kind of filtration used with Greek yogurt’s acid whey,” Moliter said.
According to Molitor, the CDR is going to “keep trying to move the needle” and continue researching the different avenues of filtering acid whey and isolating the individual pieces of this otherwise unimposing by-product.
So, as Greek yogurt production continues to grow, its once-bothersome acid whey could soon become a beloved resource.
“Acid whey is just another raw material to work with and make things out of,” Molitor said. “You know the saying: When life gives you lemons, you make lemonade.”