Food scientists at the National University of Singapore (NUS) have given okara, the residue from production of soy milk and tofu which are often discarded, a useful commercial application.
They have successfully turned okara into a refreshing drink that contains live probiotics, dietary fibre, free isoflavones and amino acids. By encapsulating these nutrients in a beverage, they can be easily absorbed into the body, and promote gut health.
Created using a patented, zero-waste process, the tasty drink can be stored at room temperature for up to 6 weeks yet able to retain high counts of live probiotics to better deliver health effects. This is unlike presently available probiotic drinks which are mainly dairy-based and require refrigeration to maintain their levels of live probiotics. These beverages also have an average shelf-life of 4 weeks and do not contain free isoflavones which have a host of health benefits.
“Okara has an unpleasant ‘fishy’ smell and tastes bland with 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,” said the Project Supervisor, Associate Professor Liu Shao Quan from the Food Science and Technology Programme at the NUS Faculty of Science.
Annually, about 10,000 tonnes of okara are produced in Singapore and it is usually discarded by soy food producers due to its unpleasant odour and sour taste. The idea to use okara to produce a drink was first conceptualised by Vong Weng Chan, a PhD student from NUS Food Science and Technology Programme. She said, “Fermented soy products, such as soybean paste and miso, are common in Asian food culture.” Rather than disposing unwanted okara, she came up with an idea of using fermentation to convert it into something that is nutritious and tastes good. With guidance by Assoc. Professor Liu, Ms Vong experimented with up to 10 different yeasts and 4 enzymes to finally come up with an ideal combination which results in a fruity and refreshing beverage.
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 fibre and amino acids.
The NUS researchers have filed a patent for their novel technique, and are currently experimenting with different enzymes and microorganisms to refine their recipe. They are now looking to collaborate with industry partners to introduce the drink to consumers.
Assoc. Professor Liu said, “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.”