Extracting dollars from Greek yoghurt waste

While the booming popularity of Greek yoghurt is great for manufacturers’ profits, it’s not so good for the environment. Production of the tangy yoghurt produces acid whey which, if not disposed of properly, can cause environmental problems.

Most companies deal with it by paying to spread it on farmers’ paddocks or dump it down the drain. Others send it to anaerobic digesters, where it is fermented to produce methane.

But University of Wisconsin-Madison scientists have found a way to deal with the by-product that’s good for both the environment and companies’ hip pockets.

“The whole goal is to take this problematic mixture of stuff - acid whey - and isolate all of the various components and find commercial uses for them,” said Dean Sommer, a food technologist at the Wisconsin Center for Dairy Research (CDR).

Sweet whey from cheese production has been used for well over a decade to produce high-value whey protein powders. However, acid whey isn’t as easy to work with as its sweet cousin.

It contains far less protein, which is considered the valuable part of the whey. Some of the other ‘solids’ in acid whey - such as lactose, lactic acid, calcium, phosphorus and galactose - also make it harder to process. The galactose and lactic acid turn acid whey into a sticky mess when it’s dried down.

So, instead of drying it, CDR scientists are developing technologies that use high-tech filters - or membranes - to separate out the various components.

“We’re taking the membranes that are available to us and stringing them together and developing a process that allows us to get some value-added ingredients out at the other end,” said dairy processing technologist Karen Smith, who is also working on the project.

The CDR has singled out lactose as the ingredient to focus on, as food companies will pay good money for food-grade lactose.

“It’s the lowest-hanging fruit; the most valuable thing in there in terms of volume and potential worth,” said Sommer.

A number of Greek yoghurt manufacturers have reportedly already implemented lactose-isolating technology in their commercial plants.

The researchers’ ultimate aim is to strip the acid whey of its useable ingredients until there’s nothing left. “It will be just water,” Sommer said.