Researchers at the National University of Singapore have devised a clever (and tasty) way of using up leftover whey from tofu production - they've turned it into a new alcoholic beverage with health benefits, known as sachi.
Associate Professor Liu Shao-Quan and PhD student Chua Jian-Yong, both from the Food Science and Technology Programme at NUS, were keen to see if they could transform the excess tofu whey into something useful. Tofu, which is created by curdling freshly boiled soy milk, then cooling it and pressing it into a block form, produces tofu whey when the solids are pressed into form. Usually this is discarded, but throwing it away can cause problems - the protein and soluble sugars in the whey are thought to deplete oxygen in the waterways the whey is dumped into.
Mr Chua, who studied alcohol fermentation during his undergraduate degree, added sugar, yeast and acid to the tofu whey to ferment it. The resulting drink, known as sachi, is pleasantly fruity and sweet, say the researchers. “[It’s] a light, wine-like brew,” says Mr Chua. “It has a sake-like profile.” Sachi can be drunk neat, and has a shelf life of around four months, as opposed to tofu whey, which only lasts a day. At the moment, Mr Chua is looking into ways to double this shelf life.
Interestingly, the fermentation process also transforms the isoflavones present in the tofu whey, and turns them into “free isoflavones.” Isoflavones are compounds found in soy products that have been linked to strengthened immunity and protection against DNA damage. Free isoflavones are more readily absorbed by the body.
The researchers are currently looking for partners to make sachi available to the public.