The Soy Foods Blind Spot: Why Okara Needs Decentralized BSF Bioconversion, Not a Truck to a Feed Mill That No Longer Wants It

Soy foods are one of the quiet success stories of the global protein transition. Soy milk, tofu, tempeh-adjacent products and plant-based beverages sit in the chiller aisles of nearly every major market, and food manufacturers and sustainability teams are proud of the low-carbon-protein story they tell. But every soy processing line has a second output that rarely appears in the sustainability report: okara, the fibrous pulp left in the filter after the soy slurry is pressed. It is wet, it spoils quickly, and for many producers it has become a disposal cost rather than a by-product with a buyer. For ESG teams, municipalities and food-sector waste managers, okara is a textbook blind spot. This article sets out why decentralized Black Soldier Fly (BSF) bioconversion, done at or near the processing line, is a better answer than the status quo.

How much okara are we talking about?

The numbers are larger than most people expect. According to Tetra Pak's technical overview of soy processing, one kilogram of dry soybeans typically yields around 2 kg of okara alongside about 10 kg of final beverage, which means okara volume is roughly one fifth of the finished soy product. The same source puts the scale for a single country in perspective: China consumes about 14 billion litres of soy beverages a year, which implies on the order of 2.8 billion kg of okara from that stream alone. Add tofu production across East and Southeast Asia and the wider soy-foods sector, and the global figure is plainly very large, even though no authoritative single global total is widely published.

What is in that pulp is just as important as how much there is. Tetra Pak describes okara as roughly 80% water, with the balance made up mostly of fibre plus residual protein. With traditional extraction methods only about 60% of the bean's protein reaches the end product, which leaves around 40% behind in the okara. In other words, the waste stream still carries a meaningful share of the nutrition that the supply chain paid to grow, ship and process. From a resource-recovery standpoint, this is not a low-value residue. It is protein and fibre locked inside water.

Why the conventional routes are failing

Okara is highly perishable. The same high moisture and nutrient density that make it attractive as a substrate make it prone to rapid putrefaction, and producers are advised to remove it from the facility as quickly as possible. That single constraint shapes everything downstream.

Animal feed is losing its grip. Historically, okara was often sold or given away to nearby pig farms. Tetra Pak notes that this route is now considered inefficient because of the shift toward formulated feeds. Where it still happens, it depends on a farm being close, on regular collection and on the farm's tolerance for a product that is 80% water and spoils within a short window.

Paying a waste dealer is the fallback. Where there is no high-value okara processing facility within reach, producers pay a specialist waste contractor. The material's water content means it needs leak-proof trucks or containers, which adds cost and logistics burden. Hauling a product that is mostly water over long distances is exactly the kind of inefficiency that decentralization is designed to remove.

Landfill and centralized digestion are poor fits. Organic waste dumped in landfill generates methane, a gas with a global warming potential of roughly 80 times that of CO2 over 20 years according to IPCC AR6, and methane emissions from organic waste are now squarely in the sights of climate policy after the Global Methane Pledge and successive COP decisions. Anaerobic digestion can handle okara, but it requires transport to a centralized plant, and digestion captures energy rather than returning protein to the food system. Neither route keeps the value where it was created.

Upcycling into human food is real but selective. Okara can be turned into flours, snacks and other products, and a handful of manufacturers have built businesses around it. But that requires drying, quality control and a food-grade supply chain, which is practical only for some producers at some scales. For the many small and mid-sized tofu and soy-milk makers who lack that capability, the question remains what to do with the volume that cannot be upcycled.

The BSF case: matching the biology to the problem

BSF larvae (BSFL) are voracious converters of wet, nutrient-rich organic matter, which is precisely the profile of okara. The evidence base here is encouraging. In a widely cited comparison of BSF rearing on different organic by-products (Bava et al., Animals, 2019), okara had the highest crude protein and ether extract contents among the substrates tested, and larvae reared on okara showed the highest indexes for waste reduction and for efficiency of converting ingested feed. That is a strong result for a decentralized operator whose economics depend on turning a disposal problem into biomass. It is also worth being fair about the limits: in the same study okara was not the top performer for final larval weight, and diet composition clearly matters. Practical operators typically blend okara with a bulking or complementary substrate to balance moisture, structure and nutrient ratios, and they should expect to tune the recipe rather than treat okara as a drop-in feedstock.

Where BSF bioconversion lands clearly ahead of the alternatives is in what happens to the output. Larvae can be processed into insect protein and oil for sustainable animal feed, and the residue left behind, frass fertilizer, returns nutrients and organic matter to soil, supporting soil health and regenerative agriculture. That closes a loop that is genuinely circular: soybeans become food, the unavoidable residue becomes feed and fertilizer, and the nutrients that would otherwise be lost to landfill or digestate streams re-enter agricultural production. This is waste valorization in the most literal sense, and it is exactly the kind of resource recovery that corporate sustainability teams can describe credibly in ESG disclosures.

Why decentralization is the decisive advantage

Okara's perishability is the strongest argument for a decentralized model. A BSF unit installed at, or very close to, the processing site can take the pulp within hours of production, before spoilage drives odour, pathogen growth and methane formation. That has four practical consequences.

First, speed. Centralized collection schedules, consolidation hubs and long hauls all give moist organic waste time to degrade. Onsite or near-site bioconversion shortens the interval between generation and treatment to hours rather than days, which directly reduces fugitive methane emissions and nuisance risks.

Second, transport emissions. Moving 80%-water material by truck is carbon-intensive per unit of dry matter. Eliminating or shortening that haul reduces the Scope 3 emissions that food brands increasingly have to account for under GHG Protocol-aligned inventories and SBTi targets, because a manufacturer's waste treatment sits inside its value-chain footprint.

Third, land use. A modular BSF facility has a small footprint compared with a centralized digester or composting site, which matters in dense industrial zones across Asia where land is expensive and permitting for new large waste infrastructure is slow.

Fourth, resilience and optionality. Distributed capacity does not depend on a single plant staying open, on a single road staying clear or on a single contractor staying in business. For producers exposed to tightening organic waste diversion rules, EPR-style cost allocation and rising disposal fees, that independence is a real hedge in climate resilience terms.

What a credible deployment looks like

None of this means a BSF unit is a plug-and-play appliance. A realistic okara project has a few ingredients. The first is feedstock design: okara's high moisture needs to be balanced, for example with a drier, structural co-substrate, so that larvae get a workable texture and airflow. The second is regulatory clarity: rules on which substrates may be used to produce insect-derived feed and fertilizer differ by jurisdiction, and clean, single-source food-grade residues such as okara are generally the easiest category to defend because there is no mixed-waste or contamination ambiguity. The third is offtake: the economics improve when protein, oil and frass each have a named buyer, whether that is an aquafeed producer, a pet-food maker or a local farm cooperative. The fourth is measurement: an LCA-based comparison of baseline disposal against onsite bioconversion gives the sustainability team defensible numbers for its carbon footprint and net zero reporting.

The bottom line

Okara is the kind of waste stream that sustainable food brands do not like to talk about: not because it is hazardous, but because it is ordinary, wet, unglamorous and large. The conventional answers (a pig-farm arrangement that is fading, a paid contractor hauling mostly water, or a landfill that turns it into methane) all treat it as something to get rid of. BSF bioconversion treats it as what it is: a clean, protein-bearing feedstock whose value decays by the hour. Done at the point of generation, it cuts transport and methane, shrinks land use, and turns a disposal line item into feed-grade protein and soil-ready fertilizer. For soy-food manufacturers and the municipalities that host them, that is a circular economy story that holds up under scrutiny, and decentralization is what makes the biology work at the speed the waste demands.

B-BOX designs decentralized Black Soldier Fly systems for organic waste treatment. To explore an onsite pilot for your processing line, get in touch with the B-BOX team.

Sources

• Tetra Pak, "Everything you need to know about okara" (soy processing yields, composition, perishability, disposal routes, China soy beverage volumes): https://tetrapak.com/insights/cases-articles/everything-you-need-to-know-about-okara

• Bava L., Jucker C., Gislon G., Lupi D., Savoldelli S., Zucali M., Colombini S. (2019), "Rearing of Hermetia illucens on Different Organic By-Products: Influence on Growth, Waste Reduction, and Environmental Impact," Animals 9(6):289, doi:10.3390/ani9060289.

• IPCC AR6 WGI, Chapter 7 (methane global warming potential over 20 years).