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But according to a report published Wednesday on the website Modern Farmer, the production of Greek yogurt, now a $2 billion-per-year industry, involves straining a byproduct called acid whey—described as watery, cloudy slop—from the yogurt. There's nothing intrinsically toxic about acid whey. However, in large quantities it can be harmful to the environment and no one quite knows what to do with it.
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"Greek yogurt companies strain whey for two reasons," Christopher P. Schlottmann, Ph.D., associate director of environmental studies at New York University. "When it's removed, it leaves yogurt with a very creamy texture and it also allows the yogurt to have more protein because there's less whey to dilute it." The problem is, straining the yogurt to such a degree requires adding more milk (to get a large quantity of yogurt in the end), which means more whey to strain. For every four ounces of milk used in the production of Greek yogurt, only one ounce makes its way into a supermarket container; the other three ounces are concentrated acid whey, which for now, serves no purpose.
It's illegal to simply pour it into the ground because it would pollute the waterways and its high acidic content would harm the soil. "Not knowing what to do with excess acid whey is not a new problem," says Schlottmann. "We've never really known what to do with it; however it's being produced in higher volumes because Greek yogurt is so trendy right now."
As a temporary solution, yogurt-makers are paying farmers to take it off their hands and feed it to cows, which can harm their digestive systems if consumed in large quantities or selling it to body builders in large tubs. According to Modern Farmer, cheese companies face a similar issue with an abundance of their own whey byproduct but theirs is sweeter, less acidic, and can be easily used as a baby formula ingredient. That would be an ideal solution for acidic whey. However, according to Dave Barbano, a food scientist at Cornell University who specializes in filtration methods for separation and recovery of protein, the first step would be extracting acid whey's small traces of protein in a cost-efficient way, and his research is just getting underway.
For now, the Greek yogurt industry is running out of options. "These companies could always maintain their creamy product by adding shorteners or thickness but the yogurt would lose some of it's protein content," says Schlottmann. "There may be a way to process it more to see if any nutrients could be extracted from the stuff but that's unlikely because minerals are cheap enough."
On Wednesday, Chobani, a popular Greek yogurt company, sent a statement to PS magazine that read:
"At Chobani, we are committed to being a good community partner. That includes finding responsible uses for whey, a natural byproduct of the process to create authentic strained Greek yogurt. We are constantly exploring the best ideas and options for beneficial whey use. Right now, we choose to return whey to farmers, most of whom use it as a supplement to their livestock feed. Some is used as a land-applied fertilizer but only at farms that have nutrient management plans in place with the state environmental conservation agency. A small percentage is also sent to community digesters, where the whey is used to produce energy."
The good news? You don't have to quit your Greek yogurt habit just yet. "The dairy industry's huge carbon footprint has less to do with an abundance of acid whey—they use lots of resources for land, greenhouse gases and animal feed," says Schlottmann. "The issue of excess acid whey is a problem but it's minor in comparison."