A new alcoholic drink rich in isoflavones has been made from whey that is usually wasted during tofu production.
The National University of Singapore research team, headed by Associate Professor Liu Shao Quan and PhD student Chua Jian Yong, have named the drink sachi.
In tofu-making, soybeans are ground into soy milk before being coagulated and pressed into solid tofu. The two main by-products collected and wasted are okara and tofu whey.
“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 very wasteful,” said Chua.
Added Prof Liu: “The health benefits associated with soy products, coupled with changing preferences towards vegetarian diets, have fuelled the growth of tofu production. As a result, the amount of tofu whey has also increased proportionally.
“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.”
When tofu whey is discarded as untreated waste, it creates environmental pollution as the protein and soluble sugars in the whey could contribute to oxygen depletion in waterways.
Once the team collects the whey, it adds sugar, malic acid and yeast, and puts it through a process of pasteurisation to kill bacteria. The liquid is then fermented in controlled conditions to produce the new alcoholic beverage.
Keep it cool
The total time required to make a batch of sachi, including the tofu-making process, takes about three weeks. It has a shelf life of about four months if refrigerated.
This first alcoholic beverage made from tofu whey does not appear to have a soybean taste or smell, but is noticeably fruity and sweet. While its texture has a similarity to sake, its taste resembles white wine, and its aroma is fragrant and floral.
The bound isoflavones present in the tofu whey are also biotransformed into free isoflavones that can be absorbed more easily by the body. It is also light and easy to drink.
The team has filed a patent for the sachi-making process. Chua said that they hope that this “repurposing of a food by-product” will be a success in East Asia.
He said that one of the next steps is to find an industry partner that will allow them to work with whey from their tofu production, in an industrial environment and scale.
Another step is to attempt to extend the shelf life of sachi, without having to use preservatives such as the commonly-used sulphur dioxide.
He added that it will be some time more before sachi gets on store shelves, and they will have to consider how to market the product once they achieve industrial success.
“It’s completely different from beer, saké, wine, etc. It’s in a completely new category on its own. We need to help it to find its own footing,” said Chua.
Last week we revealed how waste from soy milk and tofu production has also been transformed into a nutritious ingredient.
Source: Lester Wan, Food Navigator