Why Avocados Turn Brown

The Spruce / Leah Maroney

Avocado has to be one of the most popular and particularly healthy fruits in the kitchen. Its uses are seemingly endless. However, using an avocado usually means leaving it until the last minute because, once cut, the surface of the fruit quickly turns brown. Avocados have an enzyme called polyphenol oxidase under their skin. Once the avocado is cut, the enzyme comes into contact with oxygen in the air, turning the surface of the flesh brown.

There are several common solutions to this problem, including leaving the pit in the center, covering the avocado with lemon juice, placing a skinless avocado in water, or storing a cut avocado in an airtight container with a cut onion. All of these methods will slow down the browning process, but because they affect either the flavor or texture of the avocado flesh, they are less-than-ideal solutions for many cooks.

A better method for preventing avocados from going brown is to blanch the fruit whole before cutting it. Once the fruit is cut, its flesh can be exposed to air for several hours without significant browning. This technique is taught by the famous French-born British chef Raymond Blanc. As Chef Blanc explains, this method works by killing the enzyme that causes browning when the avocado flesh is exposed to air.