How much cheaper is waste cooking oil compared to food-grade rapeseed oil?

Food-grade rapeseed oil runs $0.85-1.30/kg in 2026 depending on region and contract vs. spot. Waste cooking oil (used frying oil, restaurant trap waste, tallow/animal-fat blends) runs $0.25-0.60/kg. That's a 40-70% feedstock cost reduction on a per-kg basis. For a process where oil is 40-55% of COGS, switching to WCO can drop total COGS by 15-30% before accounting for any titer or yield impact.

What's the typical titer hit when switching to WCO?

For S. bombicola sophorolipid: 5-15% titer reduction typical. For engineered P. putida rhamnolipid: 8-20% reduction typical. The range reflects WCO variability. Clean, filtered WCO from a consistent source can approach food-grade performance. Highly-oxidized or high-animal-fat WCO (tallow) shows bigger titer drops. A predictable WCO supply from a single restaurant-grease processor is much more valuable than an unpredictable mix.

What process controls make WCO workable at scale?

Three things matter. First, incoming feedstock QC: free fatty acid content, peroxide value (oxidation indicator), moisture, filtration to under 100 microns. Reject batches outside spec. Second, feed-rate modulation: WCO feeds are typically slower than food-grade to give the organism time to metabolize complex fatty acid mixtures. Third, DSP polishing: one extra filtration or adsorption step handles residual color and odor that WCO feedstock introduces. Budget an extra $1-3/kg for polishing.

Is there a regulatory issue with WCO feedstock for consumer products?

For industrial cleaners, agricultural products, and enhanced oil recovery: no issues. For personal care and cosmetics: depends on jurisdiction and label claims. Most regulators accept WCO-derived biosurfactants as long as the final product meets the relevant purity spec, but the documentation burden is higher. For food-contact or oral-consumption applications: most producers stick with food-grade feedstock to keep the regulatory path clear.

Does Augur model the WCO feedstock explicitly?

Yes. The scenario builder has a feedstock selector with rapeseed, palm, waste_oil, and custom options. Selecting waste_oil applies a default 10% titer penalty, 30% lower cost, and flags a 'feedstock variability' risk factor on the result. Users can override the titer penalty and cost values based on their specific WCO supply. The Monte Carlo sampling on COGS includes feedstock cost variability as one of the input distributions, so the confidence interval reflects supply-price uncertainty.

Waste cooking oil as a biosurfactant feedstock: COGS impact and operational tradeoffs

Feedstock cost is 40-55% of COGS for most biosurfactant processes, and it's the one cost that scales linearly with production volume. Every kg of feedstock you save on the input side is roughly a 0.4-0.55 kg saving on the output-cost side. Switching from food-grade vegetable oil to waste cooking oil (WCO) is the most underused COGS lever in the category because it sounds risky and most teams have never run it. This post quantifies the actual economic impact, what titer hit to expect, and the process controls that make WCO workable at scale.

The feedstock spread

2026 spot prices for lipid feedstocks:

Food-grade rapeseed oil (canola): $0.90-1.30/kg
Food-grade palm oil: $0.75-1.10/kg (sustainability issues for some markets)
Food-grade soybean oil: $0.85-1.20/kg
Industrial-grade rapeseed (technical grade): $0.65-0.95/kg
Waste cooking oil (clean, filtered): $0.40-0.60/kg
Waste cooking oil (unfiltered restaurant grease): $0.25-0.45/kg
Animal tallow: $0.20-0.50/kg (supply constraints in some regions)

The spread between food-grade and WCO is $0.30-0.90 per kg of feedstock. For a sophorolipid process consuming 150 g of oil per g of product, that's $4.50-13.50 per kg of product in feedstock savings alone. Against a $22-28/kg baseline COGS, that's 15-50% reduction.

Titer and yield impact

WCO contains a higher proportion of free fatty acids (FFA, 3-15% by mass depending on source) and some oxidized species that food- grade oil doesn't. Both affect the fermentation:

FFA inhibition. Free fatty acids at concentrations above 5-10% inhibit microbial growth for many yeasts and bacteria. The organism slows down until FFA is metabolized. Titer drops 5-15% typical.
Chain-length distribution. WCO has variable fatty-acid chain-length distribution (more C16/C18 from restaurant frying, less C14). For sophorolipid, which has fatty-acid tails in its structure, this shifts the product composition slightly. Acceptable for industrial applications, needs characterization for cosmetic-grade product.
Trace contaminants. Restaurant grease can contain trace antimicrobials, frying additives, or degraded oxidation products that inhibit the organism. A good WCO supplier pre-filters and deodorizes, which mitigates this.

Net titer impact: 5-15% reduction for sophorolipid, 8-20% for rhamnolipid. The range reflects WCO quality. Clean, filtered WCO from a single consistent supplier can approach food-grade performance. Mixed restaurant-grease supply shows bigger drops.

Process controls for WCO feedstock

Incoming QC

Three specifications to enforce at receiving:

Free fatty acid content under 5% (measured by titration, quick test)
Peroxide value under 20 meq/kg (indicates oxidation level)
Moisture under 0.5% (higher moisture promotes hydrolysis)

Reject batches outside spec rather than blending them in. Blended feedstock produces inconsistent fermentation behavior that propagates to inconsistent product, which is the worst possible outcome. A clean reject protocol with a reliable second supplier costs less long-term than trying to salvage marginal WCO.

Feed-rate modulation

WCO feeds slower than food-grade because the organism needs time to metabolize complex fatty-acid mixtures. Typical adjustment: reduce peak feed rate by 20-30% and extend the fed-batch phase by 15-25%. The process runs longer per batch but avoids the substrate-inhibition spikes that WCO introduces at faster feeds.

DSP polishing

WCO introduces some color and odor into the final product that food-grade feedstocks don't. One extra polishing step handles this:

Activated carbon adsorption in the UF/DF loop: $0.50-1.00 per kg additional consumable cost, removes 60-80% of color compounds
Steam stripping in the finishing step: $0.30-0.80 per kg, removes residual odor

Budget $1-3/kg additional DSP cost for WCO feedstock to maintain equivalent product spec.

Net COGS impact

Putting it all together for a 20,000 L sophorolipid process at 150 g/L food-grade baseline:

Baseline (food-grade rapeseed): 3,500 kg/batch, $24/kg COGS
WCO (clean filtered, 10% titer hit): 3,150 kg/batch. Feedstock savings: $6/kg. DSP polishing cost: $1.50/kg. Net: $19.5/kg COGS.
WCO (unfiltered grease, 15% titer hit): 2,975 kg/batch. Feedstock savings: $9/kg. DSP polishing cost: $2.50/kg. Net: $17.5/kg COGS.

The unfiltered-grease scenario gives the biggest dollar savings but introduces meaningful batch-to-batch variability. For industrial-cleaner applications where product spec is forgiving, it's a net win. For cosmetic or consumer-facing applications, the clean-filtered WCO is usually the better tradeoff.

What the platform models

Feedstock selection appears in the scenario builder with defaults for waste_oil: 30% cost reduction, 10% titer penalty, 'feedstock variability' risk factor flagged on the result. Users can override any of these based on their specific WCO supply.

The Monte Carlo sampling on COGS includes feedstock cost as a distribution (not a point estimate), so the confidence interval reflects supply-price uncertainty. If you're evaluating a WCO switch, the platform shows the cost distribution under realistic supply variability rather than a single-point answer.

If you're evaluating WCO feedstock for your biosurfactant process and want to see the predicted COGS impact for your specific strain, request access.