become rancid

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

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

A buildup of hard water minerals can result in clogging, while buildup of coffee oils left behind by brewed coffee can become rancid and cause even a fresh pot to taste bitter.

Do not use a salad oil, as it might become rancid.

However, because of their high fat content, they can become rancid when stored on countertops or in the pantry.