A by-product of traditional extracted soya production, okara has long been a headache for soya product producers, being costly and time-consuming to dispose of. But what exactly is okara, what are its properties, and could whole bean soya products be the solution that producers have been looking for?
What is okara?
Known as dòuzhā or dòufuzhā in Chinese, okara in Japanese, and biji or kongbiji in Korean, okara is the oldest of three basic types of soya fibre. The white or yellowish pulp consists of the insoluble parts of soya beans that remain after pureed soya beans have been filtered during the production of soya beverages or tofu. Such products have been consumed for over a thousand years in East and Southeast Asia, and were typically prepared in the home. As such, the okara was rarely removed, but for modern iterations of soya products, this can be problematic when it comes to taste.
“There is more than 10% of hard fibres present in soya beans,” says Tony Zhang, a GC PSE beverage category leader at Tetra Pak, “and these lead to a chalky or sandy taste if not removed.” With modern production, a separation or filtering process is employed to remove these fibres and other large particles (along with water and some of the protein) – the resulting by-product is okara, which consists of 80% water, 4% protein, and the remainder being fibre.
While very healthy – okara has many notable uses as a delicacy or additive in Japanese, Korean, and Chinese cuisine – it is also highly perishable and susceptible to putrefaction (the process of rotting or decay in organic matter), giving it limited value as a standalone product or for further processing. Instead, it’s usually simply treated as a waste product which, given the quantity produced during commercial production of soya products, can be costly and time-consuming to dispose of efficiently and sustainably.
Cut down on food waste
Food waste is in focus like never before. For example, The European Union has set a target to halve per capita food waste at the retail and consumer level by 2030, and to reduce food losses along food production and supply chains. So just how much waste is associated with soya beverages?
“Typically, 1kg of dry soya beans will produce 2kg of okara and 10kg of final beverage,” says Zhang. “So, if we consider China, where 14 billion litres of soya beverages are consumed per year, that means 2.8 billion kg okara is produced – that is a huge waste.” And the challenges for producers in dealing with such waste are numerous.
Firstly, its volume is very large – the volume of okara produced is approximately 1/5 of the final soya product. Secondly, being extremely perishable, it must be removed from production facilities as soon as possible. And with an extremely high water content – 80% – special trucks or containers are required to prevent leakage.
Producers must also pay a specialist waste dealer if there is no high-value okara processing factory nearby. It was once common to sell okara as animal feed – particularly to pork farms – but advances in nutrition have rendered this use obsolete; with the rise of formulated pig feed, okara is now considered inefficient.
And such waste isn’t just a question of time and money either – there’s a nutritional cost to simply throwing away so much okara. With traditional extracted soya production, “about 60% of the protein makes it to the end product, with the remaining 40% staying in the okara – that means that 40% of the soya protein is just wasted when making soya beverages,” says Zhang.
The advantages of whole bean soya
All of this means there are numerous advantages – in terms of cost, waste and nutrition – of retaining okara in the end product, which is precisely the aim of whole soya beverages. These full-fibre beverages utilise 100% of the soya bean, meaning all dietary fibres from the bean are still present in the final beverage. And in addition to having a higher fibre and protein content than regular or traditional soya beverages, as the production process uses the whole bean, it also generates zero okara waste, which reduces water waste too.
“Whole bean soya is more nutritious, and can be made into a high-fibre, high-protein, low-calorie plant-based beverage which is a healthier choice for consumers,” says Zhang. “The viscosity of whole bean soya beverages is also usually higher than traditional soya beverages due to this higher fibre content,” he adds. “Processing this fibre in a specific, controlled way gives whole bean soya beverages their rich, creamy taste and smooth mouthfeel.”
Straightforward to upgrade existing soya lines
Incorporating okara in whole soya beverages is done early in the production process, with a focus on reducing the particle size of the fibres and carefully controlling the final texture and taste. Advances in grinding and milling technology – essentially a smart combination of grinding, shearing, and homogenization processes – means that better particle size reduction is now possible; these smaller particles contribute to the perception of creaminess and that smooth mouthfeel.
Whole bean soya beverages give a 100% yield, too – compared to just 60% with traditionally extracted soya – which, as Zhang notes, translates to “millions of Euros in cost savings per year per factory, and that’s on top of the savings in not having to deal with okara waste.” Add in the ease with which existing soya beverage production lines can easily be converted or upgraded – only limited investment in new equipment is required – and it’s clear that okara, a by-product once simply thrown away, is once again a highly regarded, nutritious, cost-efficient ingredient for food and beverage producers interested in soya.
Facts and figures
Direct comparison of a traditional soya beverage vs. a whole soya beverage, both with 3% protein content.
Summary of the article
What is okara? |
The insoluble parts of soya beans that remain after pureed soya beans have been filtered during the production of soya beverages or tofu. |
What does it consist of? |
Okara consists of 80% water, 4% protein, and the remainder being fibre. |
Why is it removed when making traditional extracted soya products? |
The hard fibres of okara lead to a chalky or sandy taste in the end product if not removed. |
Is it easy to dispose of? |
No. Being highly perishable and susceptible to putrefaction (the process of rotting or decay in organic matter), it is costly and time-consuming to dispose of efficiently and sustainably. |
Can it now be incorporated in the final product? |
Yes. Advances in grinding and milling technology – essentially a smart combination of grinding, shearing, and homogenization processes – means that better particle size reduction is now possible. |
What benefits does this have? |
In addition to having a higher fibre and protein content than regular or traditional soya beverages, as the production process uses the whole bean, it also generates zero okara waste (whole bean soya gives a 100% yield). |
How does the end product for whole bean soya differ? |
Whole bean soya is more nutritious, and can be made into high-fibre, high-protein, low-calorie plant-based beverages which are a healthier choice. They’re also characterised by a rich, creamy taste and smooth mouthfeel. |
Is it easy to upgrade my existing soya line? |
Existing soya beverage production lines can easily be converted or upgraded – only limited investment in new equipment is required. |