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Scientists turn tofu byproduct into booze

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Researchers have developed a method for turning tofu whey, a liquid generated from the production of tofu, into a tasty alcoholic beverage that they call Sachi.

The innovative fermentation technique also enriches the drink with isoflavones, which are antioxidants that have many health benefits.

“Our unique fermentation technique also serves as a zero-waste solution to the serious issue of tofu whey disposal…”

Tofu, also known as bean curd, is made from soybeans. One of the most common methods of producing tofu is by curdling freshly boiled soy milk, cooling it, and pressing it into a solid block. Tofu whey comes from the pressing process to remove excess water.

When tofu whey is discarded as an untreated waste, however, it creates environmental pollution as the protein and soluble sugars in the whey could contribute to oxygen depletion in the waterways. In contrast, upcycling tofu whey can be a means of generating economic returns for businesses.

Liu Shao Quan and his PhD student Chua Jian Yong, both from the food science and technology program in the National University of Singapore’s Faculty of Science and both of whom have an interest in sustainable food production, initiated the creation of Sachi a year ago.

“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,” Chua explains.

“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,” says Chua.

“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,” he explains.

Tofu byproduct gets better flavor and fiber

Under Liu’s guidance, Chua took about three months to come up with a unique recipe to make an alcoholic beverage from tofu whey. He first made fresh soy milk from soybeans, and then used the soy milk to make tofu. In the course of making tofu, he collected the whey. Chua then added sugar, acid, and yeast to the tofu whey, and let the concoction ferment to produce the alcoholic beverage.

Chua also designed the novel fermentation technique which utilizes the tofu whey fully without generating any waste. The whole process of making the alcoholic beverage takes about three weeks.

Altering the composition of tofu whey via biotransformation methods converts its strong beany odor into a fruity, sweet flavor, and extends the shelf life of tofu whey from less than one day to about four months.

In addition, after fermentation, the bound isoflavones that were present in the tofu whey transformed into free isoflavones that the human body can more easily absorb. The result is a refreshing beverage that is a tad sweet, with fruity and floral notes, and has an alcohol content of about 7 to 8 percent.

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The team has filed a patent for the novel process of making Sachi and they are looking to collaborate with industry partners to introduce the drink to consumers.

Source: National University of Singapore

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