become rancid

The reason it smells and tastes funky is because the omega-3 fatty acids in the seed have become rancid.

From Salon ● Oct. 17, 2021

The resulting oils "have become rancid in the processing," writes Howard.

From Salon ● Oct. 4, 2021

A: No. The milk has been ultrapasteurized, says Sandon, meaning heated to a very high temperature for a short time, so "there's nothing living in it to become rancid or sour."

From Seattle Times ● Aug. 3, 2010

Now that they have learned how to prevent it, chemists revealed that bacon, potato chips, cakes, candy and similar foods become rancid if wrapped in ordinary transparent cellulose sheets.

From Time Magazine Archive

It is a white solid fat, fusible at about 120 degrees, and exhibits very little tendency to become rancid when kept.

From The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c. by P. L. Simmonds