Soy alcoholic beverage: The next in-thing

27 Nov 2017. NUS food scientists have produced an alcoholic beverage from tofu whey, a waste product from the food processing industry.

Tofu whey is the liquid waste generated from the tofu manufacturing process. It is a nutritive substrate that can encourage bacterial growth in it once generated. This results in a foul-smelling odour within a day. Hence, storage of tofu whey by food manufacturers is not feasible and it is usually discarded. When tofu whey is disposed into sewage directly without pre-treatment (removal of the nutrients), it causes a large amount of oxygen in the water to be consumed due to the breakdown of the organic matter. This pollutes rivers and reservoirs.

A research team lead by Prof LIU Shao Quan from the Food Science and Technology Programme at the Department of Chemistry, NUS has developed a biotransformation process that converts tasteless soy whey to a tasty and flavourful alcoholic product without the addition of artificial flavourings. They have named this unique beverage Sachi (咲智), a Japanese name which means the blossoming of flowers and wisdom. The research team used a “zero-waste” approach, where tofu whey is fully utilised when making the soy alcoholic beverage, without generating any waste.

Prof Liu said, “Tofu whey contains isoflavones, a phytoestrogen present naturally in soybeans. Isoflavones are known to be an antioxidant and scientific studies have reported that isoflavones have potential health benefits, such as reduction in heart disease, cancer risk and diabetes risk.”

The research team used commercial wine-brewing yeasts, which are available from online stores, to ferment the tofu whey. The fermentation process is similar to that which is used for wine-making. Tofu whey contains amino acids and minerals that help the growth of the yeasts. Although the biotransformation of tofu whey may be inexpensive, it is a long process that requires significant storage space.

Mr CHUA Jian Yong, a Ph.D. student on the research team, added, “This alcoholic beverage has a refreshing taste, is easy to drink and tastes like sake. Even though it is made from tofu whey, it has a very mild to undetectable soy taste. All the flavours in the drink are derived from fermentation, without artificial flavours or flavour extracts.”

The researchers plan to enhance the flavour profile of the soy alcoholic beverage by adjusting the fermentation parameters to give it a more fruity and floral note.

Flowchart illustrates the process flow from soybean to the production of tofu whey and subsequent fermentation to produce soy alcoholic beverage.

Reference

Chua JY; Lu Yuyun; Liu SQ*, “Biotransformation of soy whey into soy alcoholic beverage by four commercial strains of Saccharomyces cerevisiae” INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY. Volume: 262. Page 14-22. DOI: 10.1016/01681605. Published: 2017.