Omega-3 oils: EPA/DHA is only half the specification

Buyers specify omega-3 oils by their EPA and DHA content, then discover the difference between suppliers in the oxidation numbers — which describe not what is in the oil but what has already happened to it.

The three markers

• Peroxide value (PV) — primary oxidation products, measured in meq/kg. Rises early, then falls as peroxides break down, so a low PV on its own can be misleading.
• Anisidine value (AV) — secondary oxidation products. Does not fall back, so it captures history that PV has moved past.
• TOTOX — calculated as 2 × PV + AV. The composite, and the one to put on the specification because it cannot be gamed by timing the test.

Widely used voluntary limits sit around PV ≤ 5, AV ≤ 20 and TOTOX ≤ 26. Tighter limits are achievable and worth paying for if your finished product has a long shelf life ahead of it.

Why the numbers move after you buy

Oxidation continues in the drum. A CoA reflects the oil at the point of testing, not the oil that arrives. For a sea shipment through warm waters, that gap can be significant, which is why the specification should state where the limits apply.

Practical protections:

• Nitrogen blanketing in the drum or tote, and confirmation it was actually applied.
• Antioxidant system — tocopherols, rosemary extract or ascorbyl palmitate — declared with its inclusion rate, since it becomes part of your ingredient statement.
• Temperature-controlled shipping where the value of the cargo justifies it.
• Retest on arrival against the agreed limit, with the remedy for a failure written down in advance.

The rest of the specification

• EPA and DHA in mg/g, with the fatty acid profile by GC.
• Form — triglyceride, re-esterified triglyceride or ethyl ester. These are different materials at different prices and should never be left implied.
• Species and catch origin, plus any sustainability certification you intend to reference.
• Environmental contaminants — dioxins, PCBs, heavy metals. Marine oils concentrate what the fish were exposed to.

Where disputes come from

Nearly every omega-3 dispute we hear about traces back to a specification that set TOTOX without saying whether it applied at dispatch or on arrival. Decide that at the contract stage and most of the argument disappears before it starts.