A team of researchers at the National University of Singapore have successfully developed an alcoholic beverage – called Sachi – from tofu whey leftover from the tofu production process. This development is a zero-waste approach that compliments the tofu manufacturing process.
This project was taken on a year ago by Associate Professor Liu Shao Quan and PhD student Chua Jian Yong. Both have interests in sustainable food production and are part of the Food Science and Technology Program at NUS.
“The traditional way of manufacturing tofu produces a large amount of whey, which contains high levels of calcium and unique soya nutrients such as isoflavones and prebiotics. Hence, disposing tofu whey is wasteful,” explains Chua. “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. The drink turned out to be tasty, which is a pleasant surprise.”
The process of producing tofu involves curdling boiled soya milk, cooling it and then pressing it into a tofu block. The pressing process causes excess water to be excreted from the tofu and this tofu whey is usually discarded. When left as an untreated waste, the tofu whey can negatively affect the environment by depleting oxygen in waterways. By recycling the leftover whey, tofu manufacturers can generate more profit.
The innovative fermentation technique enriches the soy whey with antioxidants called isoflavones. This can be a great selling factor for manufacturers as consumers are becoming interested in exotic and healthy foods.
“The health benefits associated with soy products, coupled with changing preferences towards vegetarian diets, have fueled the growth of tofu production. As a result, the amount of tofu whey has also increased proportionally,” Liu says. “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.”
Under the direction of Liu, Chua developed his unique alcohol recipe over the span of three months. Sugar, acid and yeast are added to tofu whey and then the concoction is fermented in order to make alcohol. The entire fermentation process takes about three weeks.
By using biotransformation methods, researchers are able to convert tofu’s beany odor into a fruity one with a sweet flavor. The process also extends the shelf life of the product from less than one day to four months. The isoflavones created during the process are easily absorbed into the human body, and the resulting beverage is slightly sweet with floral notes and an alcohol content of around seven to eight percent.
The research team has filed for a patent for their brewing process and are looking to make industry partners who can help bring Sachi to market.