Why does fried lotus root turn black

When frying lotus root, most people will find that the lotus root turns black. In fact, this is caused by the polyphenol chemicals contained in the lotus root. If you want to avoid the lotus root turning black, you should pay attention to isolating it from oxygen. It is usually more appropriate to soak it in water.

1. When women are at home, they will boil the blackened lotus root in an iron pot. At this time, the soup also turns black. Can such lotus root still be eaten? In fact, the blackening of boiled lotus root is related to the polyphenol chemicals contained in the lotus root. These guys have a common property, which is that they can combine with iron ions to form purple or blue colored complexes. Gallic acid, one of the abundant polyphenols in lotus root, forms a blue-black substance when combined with iron ions.

2. The lotus roots that have not come into contact with any ironware and are placed in the vegetable basket turn black, which is also the effect of this polyphenol substance. The polyphenols in lotus root are oxidized into chemical substances called "quinones" under the action of polyphenol oxidase (PPO). These quinones then aggregate together to form melanin. In fact, this is the reason why apples turn brown when you cut them and bananas turn black when left in the refrigerator.

3. From this point of view, as long as your lotus root is fresh, it can be eaten even if it turns black. However, black soup and black lotus root always look unappetizing. Is there any way to keep the lotus root white?

4. In fact, it is not difficult to keep the lotus root white. Blanching in 100°C boiling water for 70 seconds can render all polyphenol oxidase ineffective, thus stopping the conversion of polyphenols to quinones. However, this method is probably only suitable for dishes such as pork ribs stewed with lotus root that require a soft and glutinous texture. If you make cold lotus root slices in this way, they will no longer be black, but they will also lose their crispy taste.

5. In addition to high temperature treatment, the appropriate addition of acidic substances can also inhibit the activities of polyphenol oxidase. When making cold lotus root slices, add vinegar to the blanched lotus root slices immediately. This can avoid the catalytic effect of polyphenol oxidase to a large extent and keep the lotus root white. In fact, some ready-to-eat packaged lotus root slices contain substances such as citric acid that inhibit the activity of polyphenol oxidase.

6. How can you keep the fresh lotus roots white if you cannot finish eating them in a short period of time? This is not difficult. Although polyphenol oxidase has a strong catalytic effect, it requires the participation of oxygen so that the phenolic substances in the lotus roots can be oxidized into quinones, so isolating oxygen is also a method. Soaking the lotus root in water can delay the process of the lotus root turning black.