Waste not, want not: Food scientists in Singapore create gut-friendly drink from soy by-product

28 Aug 2018 --- Food scientists at the National University of Singapore (NUS) have developed a refreshing drink that contains live probiotics, dietary fiber, free isoflavones and amino acids from okara – the residue from the production of soy milk and tofu, which is usually discarded. The researchers say that by encapsulating these nutrients in a beverage, they can be easily absorbed into the body and promote gut health. The researchers have filed a patent for their novel technique and are also looking to collaborate with industry partners to introduce the drink to consumers.

“The okara drink can be stored at room temperature for up to six weeks, and high counts of live probiotics to better deliver health effects. This is unlike commercially available probiotic drinks which are mainly dairy-based and require refrigeration to maintain their levels of live probiotics,” Weng-Chan Vong, a Ph.D. student from the NUS Food Science and Technology Program, tells NutritionInsight. 

Moreover, she says, these beverages have an average shelf-life of four weeks and do not contain free isoflavones, which have a host of health benefits. As no dairy is used in its creation, the drink is suitable for lactose intolerant consumers as well as those looking to follow a more plant-based diet.

About 10,000 tonnes of okara are produced yearly in Singapore. As it turns bad easily, causing it to give out an unpleasant smell and a sour taste, okara is usually discarded by soy food producers as food waste.

“Okara has an unpleasant smell and taste – it smells fishy, tastes bland, and has a gritty mouthfeel. Our breakthrough lies in our unique combination of enzymes, probiotics and yeast that work together to make okara less gritty, and give it a fruity aroma while keeping the probiotics alive. Our final product offers a nutritious, non-dairy alternative that is eco-friendly,” says project supervisor Associate Professor Shao-Quan Liu, who is from the Food Science and Technology Program at the NUS Faculty of Science.

The idea of using fermentation to produce a drink from okara was first conceived by Weng-Chan Vong. 

“During my undergraduate studies at NUS, I worked on a project to examine how soy milk can be infused into different food items, and I realized that a huge amount of okara was being discarded. It occurred to me that fermentation can be one good way to convert unwanted okara into something that is nutritious and tastes good,” she adds.

Under the guidance of Associate Prof Liu, Ms. Vong took a year to devise a novel recipe that converts okara into a beverage that is fruity and refreshing. She experimented with 10 different yeasts and four different enzymes before coming up with an ideal combination.

The final recipe uses the probiotic strain Lactobacillus paracasei L26, the Viscozyme L enzyme and the Lindnera saturnus NCYC 22 yeast to convert the okara into a nutritious drink that achieves a minimum of 1 billion probiotics per serving, which is the current recommendation by the International Scientific Association for Probiotics and Prebiotics to achieve maximum health benefits. The drink, which takes about one and a half days to produce, also contains free isoflavones, which are naturally occurring antioxidants that maintain cardiovascular health, as well as dietary fiber and amino acids.

The NUS researchers have filed a patent for the technique used to create the beverage, and are currently experimenting with different enzymes and microorganisms to refine their recipe. They are also looking to collaborate with industry partners to introduce the drink to consumers.

“We expect [the product] to be cheaper than other commercially available products because okara is easily available. And if we find partners, we hope to see our drinks in the stores within 12 to 18 months,” Liu tells NutritionInsight.

“In recent years, the food and beverage industry has been intensifying efforts to develop products that appeal to consumers who are increasingly health conscious. Our new product offers soy food manufacturers a viable solution to reduce waste, and also enables them to provide a healthy and eco-friendly beverage for their customers,” says Liu.

This is not the first time researchers at NUS have created a novel gut-friendly beverage. Last year, Liu was also involved in the creation of a novel probiotic sour beer, which incorporates the probiotic strain Lactobacillus paracasei L26.

By Lucy Gunn