Ethoxyquin (EMQ) is a quinoline-based antioxidant used as a food preservative in certain countries and originally to control scald on pears after harvest (under commercial names such as "Stop-Scald"). It is used as a preservative in some pet foods to slow the development of rancidity of fats. Ethoxyquin is also used in some spices to prevent color loss due to oxidation of the natural carotenoid pigments.

Ethoxyquin was initially registered as a pesticide in 1965 as an antioxidant used as a deterrent of scald in pears through post-harvest indoor application via a drench and/or impregnated wrap.

As an antioxidant to control the browning of pears, ethoxyquin is approved in the United States and in the European Union.

In the United States, it is approved for use as an animal feed additive and is limited as a food additive to use only in the spices chili powder, paprika, and ground chili. Ethoxyquin is not permitted for use as food additive in Australia^{[citation needed]} nor within the European Union.

Ethoxyquin is allowed in the fishing industry in Norway and France as a feed stabilizer, so is commonly used in food pellets fed to farmed salmon.

Norway made this practice illegal when the EU suspended authorization in 2017 and in accordance with the suspension utilized a transition period which allowed the sale of feed containing ethoxyquin until December 31, 2019, after this date it was illegal to sell feed containing ethoxyquin. Feed containing ethoxyquin had to be used by June 20, 2020.

Ethoxyquin is used in pellets fed to chickens on chicken farms.

In 2017, the EU suspended authorization for use as a feed additive, with various dates between 2017 and 2019 for final allowance of sale of goods so that alternatives may be phased in.