How does the lotus root turn purple after blanching? Lotus root contains a chemical component, namely tannic acid, also known as tannic acid. Lotus root will turn brown when exposed to air after it is cut and peeled. The reason for discoloration is that due to oxidation, quinone polymers produced by phenols in tannins form brown pigments, that is, melanin. In order to prevent discoloration, peeled and cut fruits and vegetables can be soaked in clear water or light salt water to isolate the air and prevent oxidation discoloration. In addition, another reason for the discoloration of tannins is that they form dark tannins with metals, which will turn blue or dark green when they meet iron. It is for these reasons that it is better to avoid using iron pots and casserole when cooking lotus roots. It is best to cut lotus roots with a stainless steel knife.
Of course, you can eat it if it changes color, but it's not very nice.
Fresh vegetables are prone to browning during storage and cooking, because the natural pigments in vegetables are not stable. Lotus root is because the tissue contains flavonoids and polyphenol oxidase, which oxidizes to black when exposed to air.
In order to prevent the lotus root from discoloring, it can be scalded with boiling water 10 second after changing the knife (the time should not be too long, because polyphenol oxidase is not heat-resistant, 10 second can be inactivated); Or, soak the cut lotus root in cold water to isolate the oxygen in the air, so that it will not change color. This method is also called soaking oxygen isolation method (this method is also suitable for all kinds of vegetables that are easy to change color).
How to make lotus root slices cold and delicious? Prepare ingredients:
Lotus root, salt cold, cold vinegar, sesame oil
Recipe practice:
1. Peel the lotus root section and cut it into coins. Lotus root slices are easily broken when cut too thin, and are not easy to taste when cut too thick.
2. After the lotus root slices are cut, soak them in a big bowl of cold water.
3. Boil a pot of boiling water. After the water is boiled, add lotus root slices. Stir-fry for one minute, then take out the lotus root slices. Lotus root slices are immediately put into a large bowl of cold water, and the taste of lotus root slices stimulated by cold water is more crisp.
4. Take out the lotus root slices, add half a spoonful of salt and 2 spoonfuls of sugar. If you like something sweeter, you can put 3 spoonfuls of sugar and 2 spoonfuls of cold vinegar. Sprinkle with sesame oil.
5. If you need cold lotus root, choose the upper part of my mouth, which is especially crisp. If it is stewed lotus root, you can choose the back part. My end part tastes sweeter. After adding salt, sugar, cold vinegar, sesame oil and other seasonings, do not stir with chopsticks, because lotus root slices are brittle and easily broken when stirred with chopsticks. Just toss it in a big bowl for a few times. Keep it in the refrigerator until it tastes better the next day.
How to make lotus root not black? How to make the lotus root not black: blanch the lotus root first.
In order to keep the lotus root white, another method is to blanch the lotus root with boiling water for 70 seconds, which can inactivate the polyphenol oxidase in the lotus root, thus inhibiting the process of transforming polyphenols into quinones. However, this method is only suitable for lotus root stew soup, which will make its taste worse and lose its crisp and tender feeling when used in cold lotus root slices.
How to make lotus root not black: soak lotus root slices in white vinegar
In addition to high temperature treatment, proper addition of acidic substances can also bind the hands and feet of polyphenol oxidase. For example, adding vinegar can largely avoid the catalytic effect of polyphenol oxidase and keep the lotus root white. Method: Prepare a pot of cold water, put a certain amount of white vinegar in the cold water, and soak the lotus root in it for a while. Acidic substances can inhibit the catalytic effect of polyphenol oxidase, so that lotus root will not turn black and discolor and keep its white color.
How to make lotus root not black: soak lotus root slices in salt water
Lotus root is easy to be oxidized and discolored by air after being cut and peeled. The best way to avoid this situation is to isolate the lotus root from oxygen before frying, so in order to prevent discoloration, put the sliced lotus root into water or salt water to avoid blackening.
How to make the lotus root not black: don't cook the lotus root with iron.
Lotus root must not be cooked with iron. Lotus root in iron pot will turn black more easily than lotus root in stainless steel pot. The blackening of lotus root fried in iron pot is related to polyphenols contained in it. These guys have one thing in common, that is, they can combine with iron ions to form purple or blue complexes. Gallic acid is one of the abundant polyphenols in lotus root. It combines with iron ions to form a blue-black substance, which is the main component of blue-black ink. So don't cook lotus root with iron.