NUS scientists develop probiotic-rich functional beverage from soy waste by-product
The region's leading probiotic and microbiome event — Probiota Asia — will get underway in Singapore this month with a stellar line-up of speakers, including the likes of Blackmores, Danone, Herbalife and Life-Space, set to take to the stage.
The residue is essentially soybean pulp, also called called okara, and is typically discarded, or used as animal feed, compost or fertiliser.
However, it has now been processed for human consumption, and contains live probiotics, amino acids, isoflavones and dietary fibres.
The project was overseen by Associate Professor Liu Shao Quan, from the NUS Faculty of Science's Food Science and Technology Programme, and began with an idea proposed by Vong Weng Chan, a PhD student from the programme.
Vong was intrigued by the ability of fermentation to improve the taste of otherwise bland foods, and wanted to see she could use it to rid okara of its fishy smell, bland taste and gritty mouthfeel.
As such, a patented, zero-waste process was used to make okara more palatable and therefore, more useful. This involved a unique combination of enzymes, probiotics and yeast that lent the formulation a fruity aroma while keeping the probiotics alive.
According to the scientists, the process also allows the beverage to be stored at room temperature for up to six weeks while still retaining high counts of live probiotics.
This makes okara stand out from most dairy-based probiotic drinks, which must be refrigerated in order to maintain their live probiotic levels, have an average shelf-life of approximately four weeks, and do not contain isoflavones.
Liu told NutraIngredients-Asia: "The unique combination of the probiotics and the yeast helps the probiotics to survive, and to extend the shelf life of the drink, even without refrigeration."
Vong said the yeast also gave the beverage "a unique flavour", adding, "Another unique thing about this drink is that the okara actually helps the probiotics to survive.
"At the same time, the probiotics will break down some of the proteins in the okara, which leads to amino acids being released, resulting in added health benefits."
Turning wastage into usage
Another reason for Vong's interest in fermenting okara was the large volumes of waste generated by soymilk and tofu production.
In Singapore, about 10,000 tonnes of okara are produced annually. On its own, it spoils easily and is therefore often treated as food waste.
Guided by Liu, Vong spent a year creating a novel recipe for a beverage made from okara, experimenting with 10 different types of yeast and four different enzymes before arriving at an optimal combination: the probiotic strain Lactobacillus paracasei L26, the Viscozyme L enzyme, and the Lindnera saturnus NCYC 22 yeast.
The enzyme is added to a mixture of okara and water, producing a reaction that is then followed by the addition of a stabiliser and sweetener.
The mixture is pasteurised and cooled before the probiotics and yeast are added to it, after which it is fermented to produce the okara probiotic beverage.
The entire process takes about a day and a half to complete.
The beverage contains the minimum of one billion probiotics per serving (as recommended by the International Scientific Association for Probiotics and Prebiotics).
While the current application for the okara processed by Liu and Vong is a functional beverage, it has the potential to be used in other applications as well.
Vong told NutraIngredients –Asia: "When it comes to the technology we are using, which combines enzymes probiotics and yeast, a similar concept can be applied to make okara useful as another type of food ingredient, not just in beverages. The main idea is to put okara back into the food chain. Instead of disposing of it."
From creation to commercialisation
Liu and Vong have filed a patent for their technique, and are still trying to refine their recipe by experimenting with a variety of microorganisms and enzymes.
They are keen on collaborating with industry partners so they can finally introduce the beverage to consumers.
In fact, Liu is confident that once commercialised, the price of the finished product containing his okara formulation will be comparable to — if not lower than — that of other probiotic beverages already on the market.
He said, "Compared with commercially available dairy-based probiotic drinks, the raw material (for the okara-derived beverage) can be obtained for free, or at a very low cost.
"We are keen to collaborate with companies interested in our product, and we hope to commercialise this within the next 12 to 18 months."
