Methods to prevent yam from discoloring:

Method 1: Soak the peeled yam in cold water to isolate it from oxygen in the air.

Method 2: Immediately soak the yam slices in salt water to prevent oxidation and blackening.

Method 3: Put the yams in cold water with vinegar and vinegar, or soak them in lemon water.

The reason why yam turns black: The blackening of cut yam is due to the occurrence of enzyme browning, which causes the color to become darker. There are three main conditions for the occurrence of browning: polyphenols, polyphenol oxidase and oxygen. When yams are peeled and exposed to the air, the polyphenols react with oxygen to produce o-quinones, which are further oxidized and polymerized to form brown pigments and melanins.