Sometimes the frozen shrimp we see in the supermarket turns red, so you should pay attention to that, this kind of shrimp may not be able to buy. Why is frozen shrimp red? Is the red frozen shrimp still edible? Let's get to know.
Why is frozen shrimp red
1. The cooked frozen shrimp is red
Generally speaking, that kind of shrimp may be cooked and sold frozen. When the shrimp is cooked, it will turn red because of the astaxanthin in the body. When cooked prawns are cooked in high temperature, the protein in the prawns will coagulate when they are heated, and the astaxanthin will decompose rapidly, and the color will turn red quickly, which is normal. Note that this is not the same thing as the red shrimp below. (of course, it's not that this freezing method is better. The normal raw frozen nutrition is better than the cooked frozen nutrition and is more resistant to release
Tips: this kind of shrimp has to be cooked after it's bought home. Although it's cooked, it can't be eaten directly. Cooked and frozen is cleaned, which can be cooked directly after boiling. After thawing, clean up the shrimp line before cooking.
2. Raw frozen shrimps are also red
In another case, some raw frozen shrimps are also red. But why do raw shrimps have red ones?
Fresh prawns contain astaxanthin (astaxanthin, which is also called astaxanthin because it is red under dissociation) in their bodies. When combined with protein, they are mostly cyan or cyan white. However, this combination is not stable. With the extension of storage time or improper storage in the operation and sales, the protein in shrimp will gradually hydrolyze to simple compounds under the action of enzymes and microorganisms. Due to the change of protein, the properties of astaxanthin are not stable, so it gradually decomposes and makes the shrimp red.
However, this just shows that the quality of shrimp has declined significantly and is not fresh.
Be careful when buying frozen shrimp with unusual bright red color
Many of the fresh frozen shrimps are preserved with formalin, then soaked in industrial caustic soda, so that they expand in volume, absorb water and increase in weight. Then they are fixed and colored with formaldehyde solution water, so that the shrimps become bright in color. Generally speaking, a kilogram of shrimp can be more than doubled in weight after such processing.
However, once heated, the volume of these expanded shrimps will shrink back to their original appearance, and the taste is not as good as before. Fresh and high quality frozen shrimp should be colorless, transparent, full and elastic, and those who look big and red should be carefully purchased.
Thawing method of frozen shrimp
For frozen shrimp, if you want to achieve a good defrosting, so that its nutrient elements will not be excessively lost or damaged, if you want to make the hot water directly in your daily life, or if you want to save time and wash it quickly under the tap water, it is easy to make the nutrition of the shrimp lose its flow. Therefore, when thawing frozen shrimp, you should master certain scientific methods, such as Shrimp can be thawed well by washing it with a small water drop under tap water, or by sprinkling salt in frozen shrimp.