Food Scientists Create Probiotic Drink From Soy Pulp

Food scientists at the National University of Singapore (NUS) have given okara—the residue from the production of soymilk and tofu, which is usually discarded—a new lease of life by turning it into a refreshing drink that contains live probiotics, dietary fiber, free isoflavones, and amino acids. In a beverage, these nutrients can be easily absorbed into the body and promote gut health.

Created using a patented zero-waste process, the drink can be stored at room temperature for up to six weeks and still retain high counts of live probiotics to better deliver health effects. This is unlike commercially available probiotic drinks that are mainly dairy-based and require refrigeration to maintain their levels of live probiotics, have an average shelf-life of four weeks, and don't contain free isoflavones, which have a host of health benefits.

"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, nondairy alternative that is eco-friendly," says project supervisor Shao-Quan Liu, PhD, an associate professor at NUS.

About 10,000 tons of okara are produced yearly in Singapore. Because it turns bad easily, causing it to have an unpleasant smell and a sour taste, okara is usually discarded by soyfood producers as food waste.

The idea of using fermentation to produce a drink from okara was first conceived by Weng-Chan Vong, a PhD student from NUS. "Fermented soy products, such as soybean paste and miso, are common in Asian food culture. When I was young, my grandparents explained to me how these fermented foods are made. The fermentation process was like magic to me; it transforms bland food into something delicious," Vong says.

"During my undergraduate studies at NUS, I worked on a project to examine how soymilk 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 says.

Under the guidance of Liu, Vong took a year to devise a novel recipe that converts okara into a beverage that's 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 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 their technique and are currently experimenting with different enzymes and microorganisms to refine their recipe. They're also looking to collaborate with industry partners to introduce the drink to consumers.

"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 soyfood manufacturers a viable solution to reduce waste, and also enables them to provide a healthful and eco-friendly beverage for their customers," Liu says.

— Source: National University of Singapore