What to do with excess tofu whey

White, rosé and red might not be the only options on the wine menu in the future, after researchers from the National University of Singapore (NUS) turned tofu whey into a wine-like alcoholic beverage.

With an interest in sustainable food production, Associate Professor Liu Shao Quan and PhD student Mr Chua Jian Yong from the NUS Faculty of Science found a way to convert the waste liquid generated in tofu production into a drink named Sachi.

“Very little research has been done to transform tofu whey into edible food and beverage products. I had previously worked on alcohol fermentation during my undergraduate studies in NUS, so I decided to take up the challenge of producing an alcoholic beverage using the whey,” explained Yong.

He believed that since whey contains high levels of calcium and is rich in isoflavones — an antioxidant found in soybeans — the by-product should not be wasted.

Tofu is made from soybeans and serves as a popular protein source for vegetarians, but the way it is usually processed results in significant waste. This involves curdling boiled soya milk, cooling it and removing excess water by pressing it into a solid block. This is when the whey is developed, but most tofu companies discard this by-product, which can have a negative environmental impact. The protein and soluble sugars in whey could cause oxygen depletion in the waterways.

Therefore, the development of an alcoholic beverage using this liquid is a tasty and environmentally friendly alternative. According to Quan, changing dietary preferences are leading to an increased production of tofu, making it more important than ever to make the process more sustainable.

“Alcoholic fermentation can serve as an alternative method to convert tofu whey into food products that can be consumed directly. Our unique fermentation technique also serves as a zero-waste solution to the serious issue of tofu whey disposal,” said Quan.

To create the recipe, Chua made tofu from scratch, added sugar, acid and yeast to the whey and fermented it to create an alcoholic drink that is rich in isoflavones without generating any waste.

But who would want a bean-flavoured drink, you ask? Chua spent three months altering the composition of the tofu whey using a biotransformation method which converts its strong beany odour into a fruity, sweet flavour that has an alcohol content of about 7–8%. The whole process to make Sachi takes about three weeks and it has a shelf life of about four months.

“The drink turned out to be tasty, which is a pleasant surprise,” Yong said.

The team has filed a patent for the process of making Sachi and are hoping to make it available to consumers in the future.

Image: Associate Professor Liu Shao Quan (right) and PhD student Mr Chua Jian Yong (left), both from the Food Science & Technology Programme under the NUS Faculty of Science, successfully turned tofu whey into a tasty alcoholic beverage which they named Sachi.