As the United States' fondness for Greek yogurt has grown this last decade, so too has the amount of (wasted) liquid whey. Did you know that for every carton of yogurt, there is the equivalent of two or three more cartons of the waste product? When 770,000 metric tons of Greek yogurt is being produced in the US (as was the case in 2015), that's a lot of food waste.
Fortunately, in the not-too-distant future, this waste could be transformed into biofuel or safe feedstock additives thanks to the work of scientists in the United States and Germany. Their research has been published in the journal Joule.
"To be sustainable, you want to convert waste streams where they are made, and upstate New York is where the cows are, where the dairy farmers are, and where the Greek yogurt craze began in the United States with Chobani and FAGE," Lars Angenent, senior author and environmental engineer and microbiologist at Cornell University and the University of Tübingen, explained in a statement.
There are three major components of liquid whey: lactose, fructose, and lactic acid. By using a twin generator and adding bacteria into the mix, the researchers were able to turn the solution into an extract containing caproic acid (n-hexanoic acid) and caprylic acid (n-octanoic acid). These extremely useful compounds can be used as a biofuel or as an alternative to antibiotics for livestock.
"The agricultural market might seem smaller [than the fuel market], but it has a very large carbon footprint, and turning acid whey into a feedstock that animals can eat is an important example of the closed cycles that we need in a sustainable society," said Angenent.
And with a little extra processing, the compounds could also generate sustainable biofuels for jets.
"The fuel market, of course, operates at a lower price, but its demand is virtually unlimited," Angenent added.
This is exciting news, but as the scientists point out, there is more to be done to improve efficiency and optimize the extraction process – not to mention work out how this technology can be applied to other types of waste.
Does this offset the carbon cost of dairy production?