Greek Yogurt: Wasting A-whey

Jun 14, 2017 | Food Ingredients |

The Dirt:
Greek yogurt is an extremely popular, protein-dense breakfast (or snack). It is great on its own and can be thrown into a smoothie, mixed with almonds and fruit, or used as a substitute to make a quick dip! For these reasons, the Greek yogurt market is booming. But, as the D2D team investigated how this yogurt is made, we discovered that two-thirds of the milk used doesn’t end up in the final yogurt product and creates an unusable “acid whey.” So, we were wondering—are there ways to repurpose this by-product? 

Because of its creamy taste and texture, dense protein and low sugar content, Greek yogurt’s popularity isn’t surprising. In fact, it has almost 2x as much protein as regular yogurt and fewer calories per serving. The market is predicted to grow at least 5% a year to a 4 billion dollars by 2019. In May 2014, Mintel Market Research reported that over 300 different Greek yogurt products were sold in the U.S.  Since that boom, over 50% of consumers that purchase yogurt are buying greek yogurt.

As of 2016, Greek yogurt has assumed 38% of overall yogurt production. Additionally, it was also reported in 2016 that production of Greek yogurt had increased over 846% over the past 5+ years. Even China, South Korea, and India are launching Greek yogurt products in response to the success the products have demonstrated on the U.S. market.

Greek Yogurt broke the mold and continues to hold the consumer’s interest!

Chobani, Fage, Yoplait, and Stonyfield have all produced a variety of Greek options (including yogurt drinks and frozen popsicles). Pepsi and Arla Protein, a company headquartered in Denmark, have taken an innovative twist and are marketing Greek yogurt as a food that will “maintain, repair, and build your muscles.” Additionally, Gatorade is creating ‘night yogurt’ that helps you repair your muscles while you sleep.

And how does the science behind this product work? The protein in Greek yogurt is mostly casein, which can promote muscle synthesis during sleep.

How is Greek yogurt different than regular yogurt?

It is the straining process which sets Greek yogurt apart from the traditional yogurt products that once commanded the market. For every gallon of milk that is used to make Greek yogurt, two thirds of that gallon is discarded after straining. The nutrients from the milk are consolidated into the protein dense product. The remaining watery substance, however, is too acidic (with a pH of 4.6) and too salty to use productively anywhere else in the food supply chain. This strained residue is called acid whey and it is a mixture of lactose, galactose, calcium phosphate, and lactic acid.

Unfortunate Waste

At D2D, we are constantly trying to minimize unnecessary waste. We have discussed how to minimize food waste in your own kitchen, how to feed more people with less resources, and how to best utilize food technology (think: GMO’s). Thus, the under-utilized by-product that is created by making Greek yogurt is something that doesn’t sit well with us! In fact, on a recent visit to the Agricultural School at Cornell University, we learned about the negative impact this acid whey can have on our environment.
Every time food is processed, there is usually some type of by-product that can be fully used in some other type of capacity. For instance, some soybean oil residue can be repurposed with asphalt. A by-product of the corn used to make ethanol can be distillers grains used in animal feed. In the case of Greek yogurt, there is not the same type of effective application available, yet, for the acid whey.

In 2016, 800,000 metric tons of Greek yogurt was produced in the U.S.. The acid whey by-product from that production could fill up approximately 640 Olympic-sized swimming pools each year!

There is an opportunity here…

Where is this acid whey going?

Fortunately, a small amount of the acid whey is used to fertilize farms. However, this must be applied delicately as too much of it used consistently can change the pH of the soil and nearby waterways.

Naturally, water has a pH of 7. As a reference point, acid rain is between 5 and 5.5, so to put acid whey with a pH of 4.6 into the environment is not beneficial for either the soil or the water. The soil would turn into a perfect environment for weeds and conifers— not crops. The run-off into the waterways can kill the fish and the phosphorus can create the algae blooms.

Finally, when exposed to hot weather and the sun, acid whey emits an awful odor, – think sour milk – which is not ideal if you are a neighbor.

Because of the protein and sugars still in the liquid, some of it can be used for animal feed. But, unless it is mixed carefully, it can cause bloating and digestive issues for the animals.

Most of the unused acid whey is sent to the municipal waste system. These huge holding tanks process liquids in an anaerobic environment. Acid whey works well to help break down the waste because the protein and sugars help the fermentation process. However, none of these alternatives add economic value to the dairies or fully utilize the nutritional value of milk.

Water A-Whey

What really caused the D2D team to pause and consider whether Greek yogurt was worth the added protein, was when we thought of all the water that is wasted in addition to the milk.

According to Tristan Zuber, Dairy Processing Specialist at Cornell, “For every four pounds of Greek yogurt manufactured, about three pounds of acid whey is produced. When you think of the various factors that contribute to create a gallon of Greek yogurt, you can extrapolate that two-thirds of that is not fully utilized for human or industrial use…

A dairy cow drinks about 40 gallons of water a day to make about 8 gallons of milk. So for the yogurt that is made from one gallon of milk, the dairy cow must drink five gallons of water. And because not all of this milk is being consumed, inevitably the water the cow drinks to make a gallon of milk is not being fully utiltized. So each time you eat a 5.3 oz of Greek yogurt you are wasting a 26 ounces of water— about three glasses.”

This is not to mention all the water, fertilizer, and other inputs used to grow the crops to make the animal feed for the cow. Basically all of that is wasted as well when the entire gallon of milk is not fully utilized.

What is being done about this?

The cheese industry had a similar problem with the sweet whey that was produced while making cheese. However, sweet whey is less acidic and has a bit more protein so it can be sold as protein supplements. Acid whey is more of an issue, but patents have been filed to try and extract the proteins and lactose into a usable food or animal feed. Right now, when extracted it turns into a lumpy, hard material. Chobani, General Mills, and Dannon all are trying to address the problem. Arla Foods is the fourth largest dairy company in the world. Their ingredient company has found a solution to mix acid whey with Nutrilac solution to make drinks, cheese, dressings and other dairy products. One of their drinks was named ‘Best Beverage Ingredient” at the 2013 Beverage Innovation Awards.

Consumers mainly go to Greek yogurt for protein, but you can boost up your regular yogurt by…

  • Adding Almonds (18) for 6 grams or protein
  • Adding Chia Seeds (2 tablespoons) for 4 grams of protein
  • Adding Hemp Seeds (3 tablespoons) for 12 grams of protein
  • Adding Cashews (14) for 4 grams of protein

The Bottom Line:

Greek yogurt is a great protein choice, but stop and think about the acid whey floating around each time you eat your yogurt. You can get the same benefit from regular yogurt and just adding some other nutritional ingredients to make a healthy snack or breakfast. You can also purchase regular yogurt and strain it yourself to create a little more concentrated protein.

Resources:

“Acid whey yield.” Arla Foods Ingredients. N.p., n.d. Web. 14 June 2017. <https://www.arlafoodsingredients.com/industries/dairy/ingredients–solutions/cheese/acid-whey-drink/>.

 Astley, Mark. “Don’t waste your acid whey! Arla concept turns by-product into value-added dairy.” DairyReporter.com. N.p., 20 Sept. 2013. Web. 14 June 2017. 

Baumhardt, Alex. “Harmful Byproduct Of Icelandic Skyr Production Reaching The Country’s Largest River.” The Reykjavik Grapevine. Fröken Ltd. , 20 June 2015. Web. 14 June 2017. 

Gami, Sanjay, Greg Godwin, Karl Czymmek, Kevin Kevin, and Quirine Ketterings. “Acid Whey pH and Nutrient Content.” Agronomy Fact Sheet Series. Cornell University, 2016. Web. <http://nmsp.cals.cornell.edu/publications/factsheets/factsheet96.pdf>.

Johnson, Courtney. “Dairy Market: Yogurt Sales Take the Lead.” Natural Products INSIDER. Informa PLC, 17 May 2017. Web. 14 June 2017.

 Mutikani, Lucia, Jim Dickrell, and Linda Geist. “June 2017 Dairy Herd Management Issue.” Dairy Herd Management. N.p., n.d. Web. 14 June 2017.