Greek yogurt may be good for your gut, but figuring out what to do with its biggest waste product can give producers heartburn.
Thick, creamy, high in protein and rich in bacteria that aids digestion, Greek yogurt has been a trendy snack for the past several years. But straining liquid out of the yogurt — the process that makes it so creamy — produces a huge amount of acid whey, a watery dairy byproduct with a pH comparable to tomato juice, wine — or acid rain.
For every 7,000 gallons of milk used in making Greek yogurt, as much as 4,900 gallons of acid whey gets produced, according to a 2013 Cornell University report. The cost of handling and disposing of all that whey is a drag on the industry, which has been a boon to the sagging economy of upstate New York.
But it's also rich in nutrients and sugars, so researchers hope to figure out ways to cheaply break it apart and sell the components the way other dairy byproducts have been converted to profitable uses.
Cream, for instance, gets sold on its own or made into butter. Even cheesemakers have figured out how to make nutritional supplements out of the less-acidic whey left behind from their work, Cornell University agricultural economist Andrew Novakovic told VICE News.
"The yogurt guys really haven't come up with a formula yet that allows them to recover much economic value out of the whey that they're generating," Novakovic said. "They're in kind of in a least-loss situation, which is where the cheese industry was 50 years ago. There's definitely things you can do, not for the lack of technology, but most of these technologies cost more than the value of the product that they make."
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So most acid whey gets dumped on fields as fertilizer or added to animal feed, said Dean Sommer, a cheese and food technologist at the University of Wisconsin's Center for Dairy Research. But there are limits to how much can be spread onto the land, "because of how much the soil can handle," Sommer told VICE News. "They don't want it running off into streams and such."
Previous whey spills have been blamed for killing thousands of fish as the organic material decays, depleting the surrounding water of oxygen — a problem that's not unique to acid whey. In 2011, the owner of a hog farm in Ohio was sentenced to six months in prison and fined more than $50,000 for letting thousands of gallons of cheese whey spill into a nearby creek, killing more than 36,000 fish.
Acid whey isn't exactly tasty, but it's not toxic when eaten; it sometimes rises to the top of a yogurt container before it's opened, Novakovic said. "It will have a little tartness to it, but it's not going to burn your tongue."
It's also rich in proteins, calcium and milk sugars, Sommer said. It's those compounds that researchers hope to extract.
"We believe we can grab some of the lactic acid out of the acid whey and utilize the lactose from it," he said. "There's a lot of things in there that in of themselves that have value," he said. "The problem is that when they're all mixed together in this thing that we call 'acid whey,' they're problematic."
Acid whey can also be used to produce galactose, a sugar that may help the gastrically challenged. "Lot of people are lactose-intolerant but can tolerate galactose," Sommer told VICE News.
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Chobani, the biggest player in the Greek yogurt market, found another use for the waste in a massive plant it built in Twin Falls, Idaho. The company uses reverse osmosis to extract water from the whey, using the liquid for cleaning and leaving the remainder in a more concentrated form. That means it draws about 20 percent less water from city reservoirs and runs fewer trucks to get rid of the remainder, the company said.
And some acid whey has been used in anaerobic digesters — devices that mimic the human digestive system, breaking down organic material and producing methane, which can be burned as fuel. But don't expect it to become the next miracle fuel, Novakovic told VICE News.
"Whey is mostly water," he said. "You've got to get rid of this water first, and if you just use whey only as a raw material it'd be really inefficient. But if you mix it in with a whole bunch of manure, then it kind of balances out."
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