Raw marinated crab, a unique delicacy from the southeast coast of China, is made from the plump swimming crabs harvested in winter. Since the swimming crabs are simply marinated in spicy sauce and eaten raw, their meat remains sweet and succulent, complemented by the rich, creamy roe. This dish has always been a gourmet's delight throughout the ages. For instance, an ancient poet once praised it, stating that missing the chance of enjoying raw pickled crab is a disgrace to the belly. However, it also raises concerns about food safety. In this article, we will discuss the catalog of the various parasites which exist in aquatic animals and the solutions to minimize the risk of infection.

 

Admittedly, whether it's seafood or freshwater fish, domesticated or wild-caught, parasites will always be present. The most common types of parasites that appear in animals are trematodes, cestodes, nematodes, and protozoa.

1. Among the trematodes, a typical example is Paragonimus westermani, which causes paragonimiasis (lung fluke disease). These parasites start as eggs and develop into miracidia, which infect snails (such as Semisulcospira) and then develop into cercariae. After that, Paragonimus infects freshwater fish or shrimp, where it grows into metacercariae. Finally, they enter the human body when people consume the contaminated fish or shrimp, and thus mature into adult worms.

2. As for cestodes, the most common one is the fish tapeworm, also known as Diphyllobothrium latum (broad tapeworm). These tapeworms are first consumed by copepods, which are eaten by freshwater or marine fish, crustaceans, or cephalopods subsequently. Ultimately, humans can become infected by consuming these hosts improperly, with the worms inhabiting the intestinal tract.

3. Nematode infections follow a similar pattern: Anisakis larvae first infect small crustaceans, then move to fish, and are finally eaten by marine mammals, where they parasitize.

4. Protozoa, such as Cryptosporidium, release eggs directly into the water. Consuming untreated water can lead to these parasites directly invading your gastrointestinal system.

 

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There is no denying that the high salt content of seawater, which acts as an obstacle to the survival of some parasites, makes seafood appear 'safer' than freshwater food, leading to its popularity choice among the public. However, parasites like Heterotrichous nematodes or broad-jointed tapeworms remain a sword of Damocles hanging over diners due to their salt resistance (not to mention bacteria, viruses, biogenic amines, etc. which are excluded in this article). Therefore, it is particularly important to ensure one’s health and safety, which should be achieved through two main aspects—the SELECTION OF RAW MATERIAL and the CHOICE OF TREAMTMENT METHOD.

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1. Selection of Raw Materials:

As mentioned earlier, the potential risk of seafood is relatively smaller than that of the freshwater food when preparing raw pickled dishes. However, it is essential to avoid using dead crabs. This is because the crabs' defense systems come to a halt after death, and their shells act as petri dishes, encouraging the survival of viruses and the growth of bacteria. Additionally, these bacteria can facilitate the decarboxylation of histidine and tyrosine, compounds produced from the high concentration of metabolic waste in the crab's internal organs, forming histamine and tyrosine, which can lead to poisoning if ingested by humans. Therefore, dead crabs should never be eaten.

 

2. Choice of Treatment Method:

Heat is undoubtedly the most reliable way to cook seafood, but the freshness of raw pickled crabs will also be lost in the process. Therefore, garlic, chili peppers or wine are often used to pickle and sterilize the crabs, while preserving their flavor. Unfortunately, while ginger, allicin and capsaicin have anti-bacterial properties, they are not effective against large parasites. Even though soaking the crabs in garlic juice, soy sauce, ginger juice, or horseradish do kill parasites to some extent, this process requires the parasites be directly exposed to these substances, meaning that those hiding in the crevices of the meat and the chambers of the crabs remain unaffected. Prolonged soaking in high concentration of alcohol is relatively effective and makes seafood safer, but many people dislike the taste of alcohol. Therefore, freezing live crabs for more than 7 days after treatment has become a popular choice for many gourmets. During the freezing process, water condenses and forms its ice crystals that can pierce the parasites’ cell membranes, dehydrating them and inhibiting enzyme activity, thereby disrupting their metabolic pathways. When it's time to eat, the crab is thawed, which undeniably affects some of the flavor, but it's still delicious.

 

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​In summary, while the dangers of parasites and foodborne illnesses inevitably exist, the Chinese people, from ancient times to today, have never shied away from their pursuit of exceptional flavors. The careful selection of ingredients and innovative preparation methods reflect a deep respect for both taste and safety. Yet, it is this spirit of daring and the willingness to embrace risk for the sake of culinary delight that truly defines the essence of Chinese gastronomy—an enduring love for food that transcends caution, celebrating the joy of savoring every bite, no matter the challenge. However, as we indulge in this specific dish, it is essential to assess the risks wisely and ensure that we consume raw marinated crab from reputable sources, always prioritizing safety above all. After all, the ultimate enjoyment of this delicacy lies in savoring it with peace of mind.