Can I eat yam if it turns black after being cooked?

Many people will find that peeled yams will turn black after being left for a period of time. This is due to the oxidation caused by the phenolic substances in the yams coming into contact with oxygen. Another situation is that after cooking the yam, you will find that the yam turns black. After cooking, the yam turns black, which makes many people wonder if they have bought spoiled yam. So, if it turns black after cooking, can it still be eaten?

Why does yam turn black?

The yam turns black because an oxidation reaction occurs when the fresh yam comes into contact with the air after being peeled. After the yam is peeled and exposed to the air, the polyphenols contained in the yam undergo an oxidation reaction with the oxygen in the air to produce o-quinone. If it continues to be in contact with the air, it will further oxidize and polymerize to form brown pigment and melanin. Moreover, if you use a kitchen knife to cut the yam, the yam may change color when it comes into contact with the metal surface of the knife, including the iron pan when cooking.

This phenomenon is very common in life. For example, for apples, fruits, lotus roots, etc., after being cut, the flesh will gradually become darker in color as it comes into contact with the air for a long time.

Can I still eat yam if it turns black?

Can be eaten.

The yam turns black because of oxidation, but it does not affect the edibility of the yam. There will be no problem after eating it, so you can eat it with confidence. It just won’t look very pretty when served.

How to prevent yam from turning black

1. Soak in salt water

Soak the peeled yam completely in salt water so that it will no longer turn yellow or black.

2. Soak in white vinegar

Put the peeled yam in water mixed with white vinegar so that it will not turn black.

3. Quick peeling

There are many whiskers on the skinned yam, which will slow down the peeling process. First, put the yam on the fire and quickly burn off the whiskers. This will make peeling faster and reduce the time it is in contact with air.

4. No need to cut with a knife

The yam will change color when it comes into contact with the blade of a metal knife. You can use a bamboo knife or a plastic blade to cut it instead, or use a spoon to cut a circle on the surface of the yam and then break it with your hands.

5. Heat first

To prevent the yam from changing color after coming into contact with the iron pan, put the yam with skin in a steamer or microwave and heat it for one minute. This will inactivate the polyphenol oxidase and prevent it from turning black.