Normally, crabs are frozen and thawed, then heated sufficiently to be eaten.
Crabs are mainly composed of water, protein, unsaturated fatty acids, carbohydrates, minerals and other nutrients. All these components are relatively stable and do not show any change in nature due to freezing. Whether fresh or cooked crabs are thawed after freezing and then sufficiently heated, they are all edible.
If crabs are properly frozen and preserved, there is generally no quality problem. However, if the temperature of the refrigerator is not low enough and more bacteria are present; if the crabs are thawed and then refrozen, the bacteria will grow in large quantities, prompting the crabs to develop a musty, sour and other uncomfortable flavors, then the crabs should not be eaten.
Most of the nutrients in crabs can be preserved after freezing, but some nutrients will still be lost due to freezing, so it is best to buy fresh crabs and eat them now if you are in a position to do so. If you experience discomfort after consuming frozen crabs, you need to seek prompt medical treatment.