Oxidation & Rancidity Indices

A low peroxide value can be misleading

Peroxides are intermediates. In an advanced oxidation state they have already decomposed, so peroxide value falls while anisidine value climbs. Reading peroxide value alone can make a badly oxidised oil look fresh, which is why TOTOX exists.

Antioxidant treatment is part of the specification

For fish meal, fish oil, high-fat meals and rendered fats, the antioxidant used, its dose and the date of treatment are as much a part of the specification as the oxidation indices themselves. Untreated marine cargo has a materially shorter usable life.

Typische industrielle Referenzwerte

Peroxide value	Low single digits desirable	Primary oxidation products
Anisidine value	Tracks secondary oxidation	Rises as PV falls back
TOTOX	Combined oxidation history	Preferred for marine oils
Free fatty acids	Hydrolytic rather than oxidative	Indicates handling and storage history

Indicative industry reference values for orientation only — always contract against the delivered lot.

Was zu prüfen ist

—Peroxide value, anisidine value and free fatty acids together, with the sampling date
—Antioxidant declaration: type, dose, treatment date
—Temperature history during voyage and storage

Typische Risiken

—Vitamin A and E destruction in the finished feed
—Palatability rejection, particularly in aqua and pet diets
—Self-heating in bulk marine ingredients

Häufige Fehler

—Specifying peroxide value only
—Ignoring the elapsed time between certificate date and delivery date

Häufige Fragen

Why does oxidation matter beyond the fat itself?

Oxidation propagates. It destroys fat-soluble vitamins and pigments in the same feed, reduces intake, and generates compounds that stress the animal — so the cost is rarely limited to the fat fraction that was measured.