Greek yogurt is a relatively recent food fad in the U.S. But its unique taste and thick texture appeal to many, and it accounted for as much as 51% of the nation’s retail sales of yogurt in 2021. To satisfy hungry customers, Greek yogurt production has increased, but so has a byproduct stemming from this creamy creation, one without much value. It’s called Greek yogurt acid whey, or GAW, for short.
Every pound of Greek yogurt produces about two pounds of GAW, so it poses a significant disposal dilemma. But GAW could be a boon rather than a burden. A UW research team believes they have discovered a way to turn this byproduct into a coproduct — something of value produced alongside another output — by modifying the lactose in Greek acid whey and creating a dairy-derived sweetener syrup.
Greek yogurt is made by adding yogurt cultures to milk and allowing fermentation to occur. The milk-turned-yogurt is then strained and concentrated, which removes a yellowish, acidic whey liquid. This is GAW. Its low protein and mineral content (relative to whey produced from cheese) are unappealing to manufacturers, so the most economical fate for GAW has been to discard it. It’s often spread onto farmlands or sent to wastewater treatment facilities, but its high acidity can decrease soil productivity and pollute the environment in the form of runoff.
However, nested away in GAW is lactose, a natural sugar associated with that infamous ailment lactose intolerance. The prevalence of lactose intolerance has made lactose an unattractive ingredient for food companies. But other sugars, such as glucose and galactose, are much more marketable.
“We can take lactose and very easily turn it into something that actually has a lot of functionality and value,” says Scott Rankin, professor and chair in the Department of Food Science and part of the research team. “[The GAW syrup] would be a true coproduct for Greek acid whey and a commodity that people could sell.”
Rankin and coinventors George Huber, a chemical and biological engineering professor, and chemical and biological engineering graduate student Mark Lindsay, devised a process for producing a glucose-galactose syrup (GGS) — what the researchers are calling a “dairy syrup” — from lactose. And they do this with the help of catalysts.
To transform GAW into GGS, it first needs to be filtered and purified. Then an acid catalyst is applied, which breaks lactose into two different sugars — glucose and galactose. This process is spurred by hydrolysis, a reaction that takes place in the presence of water, and the initiating catalyst. The mixture is filtered once more and then concentrated to form a syrup.
Instead of becoming a waste product, innovation has helped transform GAW into something useful. With a sweetness similar to corn syrup, GGS could be used in many food products, from soda to baked goods to ice cream, just like any other sweetener.
“I think we can be the leaders in developing this new type of dairy sweetener for the market from these underutilized dairy products,” says Huber. “We are creating value from dairy waste products that are produced today.”
The application of catalysts is new to the food industry, but there are endless opportunities.
“We could deploy this technology against just milk, ice cream, cheese — so lactose malabsorption is not an issue with dairy products,” says Rankin. “I see the potential to expand this type of technology to a very broad application in the dairy world, so more people can consume dairy.”
For now, the team is working on expanding from the lab into the real world with the help of Jarryd Featherman, a technology development lead in the UW Department of Chemical and Biological Engineering, and the Center for Dairy Research at CALS. Together, they are scaling up the technology to produce larger quantities of GGS. Potential manufacturing partners will soon be able to test out the syrup with their products — and hopefully bring this sweet solution to stores.
“Companies have spent a lot of time and resources trying to figure out a profitable way to deal with [production] waste, but no successful method has been implemented to our knowledge,” Featherman says. “The thought of our technology filling that gap and providing a new revenue stream to the dairy industry — while also improving the industry’s environmental footprint — is what keeps me motivated to bring this technology to market.”This article was posted in Fall 2022, Food Systems, Natural Selections and tagged Center for Dairy Research, Dairy, dairy syrup, Food science, greek yogurt, Scott Rankin.