Acid Whey: The Dark Side of Greek Yogurt

Greek Yogurt is one of America's favorite foods. Earliest records of Greek Yogurt trace back to the 5th century BCE in Greece where yogurt was strained with special cloths. Although it has been part of authentic middle eastern cuisine for forever now, it wasn't until 2009 that it was popularized worldwide by Chobani. 

Once it hit American shelves, it was an instant hit and it's no wonder why.

Greek has more protein, and less sugar, and tastes better than regular yogurt. In 2015, approximately 771,000 metric tons of Greek yogurt were produced in the U.S. alone. And by 2021, Greek yogurt made up more than half of all U.S. yogurt sales.

If you recall, Greek yogurt was - and still is - made by straining traditional yogurt. The substance that is strained out is a yellow liquid called acid whey. For every cup of Greek yogurt, 3-4 cups of acid whey is produced. This is all fine and dandy until one realizes the properties of acid whey.

Acid Whey has a high chemical and biological oxygen demand, meaning it requires more oxygen to dissolve into water. Acid whey is terrible for the environment, especially aquatic ones. When it enters a body of water, the oxygen is removed which leads to algal blooms, the death of fish, and the total collapse of the ecosystem. And this isn't just a niche problem, with the increasing popularity of Greek yogurt, this problem becomes even larger.

Similarly, cheese production also makes a whey, sweet whey. However, unlike acid whey, sweet whey has many uses. Because of the cheese-making process, much of the nutrients from the milk are retained in sweet whey with mainly the fat going into the cheese. This makes sweet whey an excellent source of protein. (Yes, that's where whey protein comes from) But unlike cheese-making, Greek yogurt takes most of the nutrients and protein, leaving acid whey almost useless.

There is no sustainable solution to acid whey pollution. One being used is anaerobic digestion; large vats with bacteria that digest acid whey. While it is a great method of waste removal, it is simply inefficient against large quantities of acid whey. Furthermore, it takes too long and creates methane which too is harmful to the environment.

Some farmers are even feeding the deproteinized acid whey to some cows and calves, but it is unclear whether this is enough to handle the large quantities of acid whey made.

This problem raises new questions for businesses. Who is responsible for the acid whey? There are tons of companies that create trash but can dispose of them accordingly. But with acid whey, due to the lack of proper disposal methods Greek yogurt manufacturers are dumbfounded and just dumping it. 

All we know for certain is that a reliable solution is needed, and fast.