Raise your glass in a toast to some researchers from Down Under, as they have figured out how to make ethanol out of some of the leftovers from wine-making. University of Adelaide researchers in Australia showed they could make about 100 gallons of ethanol by fermenting a ton of grape marc – the leftover skins, stalks and seeds from wine-making.
Global wine production leaves an estimated 13 million tonnes of grape marc waste each year. Nationally it is estimated that several hundred thousand tonnes are generated annually and it is generally disposed of at a cost to the winery.
“This is a potentially economic use for what is largely a waste product,” says Associate Professor Rachel Burton, Program Leader with the Australian Research Council (ARC) Centre of Excellence in Plant Cell Walls in the School of Agriculture, Food and Wine.
PhD candidate Kendall Corbin analysed the composition of grape marc from two grape varieties, cabernet sauvignon and sauvignon blanc. She also investigated pre-treatment of the grape marc with acid and enzymes.
Ms Corbin found that the majority of the carbohydrates found in grape marc could be converted directly to ethanol through fermentation with a yield of up to 270 litres per tonne of grape marc.
What was leftover from this ethanol-making process is suitable as an animal feed or fertilizer.