When soy milk and tofu are made from soybeans, a pulp known as okara is left over. Due to its fishy smell, bland flavor and gritty texture, it's typically thrown away. Now, however, scientists have developed a process of converting it into a healthy and (supposedly) tasty probiotic drink.

Vong Weng Chan, a Food Science and Technology PhD student at the National University of Singapore (NUS), initially came up with the idea of fermenting okara to make it more palatable.

"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," she says. "It occurred to me that fermentation can be one good way to convert unwanted okara into something that is nutritious and tastes good."

Under the supervision of associate professor Liu Shao Quan, she proceeded to experiment with various yeasts, enzymes and probiotic bacteria for the fermentation process. The combination that ultimately worked best included the Lindnera saturnus NCYC 22 yeast, the Viscozyme L enzyme, and the Lactobacillus paracasei L26 bacteria.

These produced a "fruity"-smelling and apparently good-tasting drink containing a minimum of 1 billion live probiotics per serving, along with high amounts of free isoflavones (naturally-occurring antioxidants that maintain heart health), dietary fiber and amino acids.

The beverage takes approximately one-and-a-half days to produce, and can last for up to six weeks without refrigeration. By contrast, typical dairy-based probiotic drinks do need to be refrigerated, and even then have a shelf life of only about four weeks. Additionally, they don't contain free isoflavones.

The researchers are now trying out different enzymes and bacteria in order to refine the process, which they have patented and are eager to commercialize. Last year, Liu worked with a different student to create a Lactobacillus paracasei L26-based probiotic beer.