How to prevent blackening of sweet potatoes after peeling

The blackening of peeled sweet potatoes can be prevented by soaking them in water, cooking them quickly, reducing exposure time, controlling the size of the cut pieces, and using acidic solutions. The oxidation blackening of sweet potatoes is mainly related to the contact of polyphenolic substances with air, and reasonable treatment can effectively delay the discoloration.

1. Soak in water

Immediately immerse the peeled sweet potatoes completely in water to isolate them from air contact. The low dissolved oxygen content in water can slow down the activity of polyphenol oxidase. Note that the soaking time should not exceed 2 hours to avoid nutrient loss. It is recommended to cut it into pieces before cooking.

2. Quick cooking

Cut into pieces and steam or stir fry within 10 minutes. High temperature can quickly inactivate oxidase. Boil the water before adding sweet potatoes during steaming to shorten the waiting time before high-temperature treatment. Microwave heating for 3-5 minutes can also effectively inhibit enzymatic browning reaction.

3. Reduce exposure time

Process sweet potatoes in batches as needed to avoid peeling too much at once. Wrap the unused parts tightly with cling film to reduce the contact area with air. refrigerated storage can delay discoloration, but it should be consumed within 24 hours.

4. Control the cutting size

Large sweet potatoes are less prone to oxidation than thin slices, and it is recommended to cut them into pieces that are at least 3 centimeters thick. The smaller the incision area, the less exposure of phenolic substances. When making mashed potatoes, some of the outer skin can be retained to temporarily prevent internal tissue oxidation.

5. Acidic solution treatment

Soak in 1% citric acid or white vinegar solution for 3 minutes. Acidic environment can inhibit enzyme activity. Vitamin C solution also has a similar effect, but may affect the sweetness of sweet potatoes. Rinse before cooking after processing to avoid residual acidity. Sweet potatoes are rich in dietary fiber and beta carotene. It is recommended to choose fresh sweet potatoes with smooth and scar free skin. Short term storage can be placed in a cool place to avoid starch conversion caused by refrigeration and affecting taste. Eating vegetables and fruits rich in vitamin C together during cooking can delay oxidation and promote iron absorption. If a blackened area is found to have an odor or mucus, it should be stopped from consumption to prevent spoilage.