SINGAPORE – The white, pasty and unpleasant-smelling waste that remains after making tofu and soy milk could revolutionize the novel food space and aquaculture.
Researchers from Nanyang Technological University (NTU) and Republic Polytechnic (RP) are working on separate projects to maximize the potential of the by-product called okara or soybean pulp, which is rich in fiber and in protein.
From the fermentation of okara, scientists at NTU were able to derive a liquid extract that contains plant growth hormones that can cause animal cells to grow and multiply in tissues, to form meat. cellular culture.
Cell culture proteins make it possible to produce meat products without slaughtering animals.
Currently, when producing cell culture meat, chicken or cow cells are usually submerged in a pink nutrient broth containing a little serum which helps the cells to grow and multiply.
But the serum comes from the blood of unborn calves of pregnant cows which are then killed.
The serum can cost up to $ 2,000 per liter. Its use in cultured meat that aims to be cruelty-free may also seem ironic, said Professor William Chen, director of the NTU’s Food Science and Technology Program, who leads okara research. “The process of harvesting bovine serum causes pain and distress in fetal calves.”
The team used a week-long process that involved fermenting okara with microorganisms, heating and adding water, to extract a yellow liquid containing the hormones.
About 200 g of okara can produce 300 to 400 ml of liquid, said Teng Ting Shien, a doctoral student in the NTU program. Research on okara fermentation is part of his thesis in Food Science and Technology.
In the lab, Teng found that muscle cells from cultured mice multiplied 70% as much as any other batch of cells treated with bovine serum.
Professor Chen said, “To find a substitute for bovine serum, other laboratories have developed generally expensive, non-food growth media. But okara is available in large quantities in the food industry, is edible. and safe, and is low cost. “
The team’s fermented okara extract can cost $ 2 a liter. The main cost factor for this new food is the growth serum.
The research team is now reaching out to local cultured meat start-ups to test the liquid extract. Singapore became the first country to approve the sale of a cell culture product last December.
At RP, the researchers concocted a cheaper food for abalone, using okara as the main ingredient. Juvenile abalone fed okara food weighed about 25% more than those fed commercial feed, and abalone shells were a brighter purple.
Dr Chiradip Chatterjee, senior lecturer at the Polytechnic of Applied Sciences, and his team developed the food pellets using technology that included pretreating okara at high temperature and mixing it with nutrients. keys.
“Abalones fed commercial feed are less striking, more greyish in color … The vibrant color of their shells may increase their sales potential.”
Although soy pulp is used as a feed for livestock, the team believe it is the first abalone feed that uses okara.
Dr Chatterjee said high-protein pellets cost up to 30% less than commercial feed, with okara replacing fishmeal, the more expensive ingredient in fish feed.
On the market, food costs between $ 1.80 and $ 2 per kilogram. Fishmeal is usually made from small fish caught from the wild and their numbers are declining, he said.
“It is possible that our okara feeds will be used with commercially available feeds to reduce the cost of aquaculture. “
The research team sourced okara from a local soy beverage manufacturer. A 2017 Straits Times report indicated that 30,000 kg of okara are thrown away in Singapore every day.
The PR team is reaching out to local and Southeast Asian abalone farms to test the okara diet in the industry.
While the high amount of fiber in okara is more suitable for herbivores like abalone, the pellets can be customized for marine omnivorous and carnivorous species such as shrimp, sea bass, and tuna, with more research.
“For carnivorous species, okara’s indigestible fiber should be reduced before expanding the diet,” Dr. Chatterjee said.