Fish dishes and delicacies are very healthy, and fishing itself brings a lot of positive emotions to a person and is one of the most favorite ways to relax. But fish meat, like other meat products, may contain helminths, which, if heat treatment rules are not followed, leads to infection. Do parasites in fish carcasses die when frozen, or is there any other way to get rid of worms? This question worries many people, because they do not refuse delicious dishes, but want to protect themselves. After all, human health in the future depends on properly carried out anthelmintic treatment of fish carcasses.
Helminthiasis of fish
Fish parasites and their danger
Various types of worms parasitize fish. Some prefer freshwater species, while others “love” marine life. Not all parasites living in fish are dangerous to humans, but there are species that can cause helminthic infection with serious consequences. Therefore, lovers of the “natural taste” of fish (stroganina, sushi) should think about whether there are parasites in such fish and whether it is safe to eat.
Recently, it has become fashionable to eat the raw product, seasoning it with salt and vinegar. But it is unsafe to cook fish in this way, since the larvae (if present) do not die, but when they enter the human body, they begin to multiply, causing symptoms of helminthiasis.
Nematode roundworms
These are the most common worms of the class Halicephalobus mephisto, having a round or spiral shape. They are able to live in fresh and salt water, so they infect fish of all types. The worms have a smooth cylindrical shape and are quite long, so when cutting carcasses they can be seen with the naked eye. Worms parasitize the intestines of fish. These can be single individuals or multiple lesions, leading to the death of their “owner”. Nematodes can reach humans from improperly prepared fish products.
Therefore, before sending carcasses to a chain of stores, all fish products are checked for the presence of helminths. To prevent infection, it is frozen.
Cestode tapeworms
These are worms that look like tape. They consist of segments and are endoparasites. Some of them use fish as a temporary shelter, forming immature specimens, which, together with poorly processed meat, fall into the human body, causing helminthiasis. Worms can grow up to 12 meters. Fish tapeworm is the causative agent of diphyllobothriasis, a severe parasitic disease. Carriers of tapeworms are freshwater fish (burbot, perch, pike, ruff). When cutting these species, special attention is paid to the gills, eggs and muscles. It is there that the helminth larvae “nest”, forming white cysts 1-2 cm in size.
Cestodes
Fluke worms trematodes
These are flat worms with a leaf-shaped body. They reach sizes of 2-20 mm. Worms are hermaphrodites, so they don't need males or females to reproduce. The development cycle of helminths is complex. First, the eggs of adult individuals living in the intestines of fish-eating birds fall into the water along with their droppings. There, larvae emerge from them and are able to move freely. They enter the body of mollusks or crustaceans, and from there into the digestive tract of fish. Parasites are localized in muscles, eyes, liver, and internal organs. When a person consumes infected fish, the parasites penetrate the gastrointestinal tract, multiply there and settle in the liver or lungs, causing trematodiasis.
Fluke
Advice! To avoid becoming a carrier of a dangerous disease, you need to know at what minimum temperature parasites in fish die. After all, different types of helminths are able to withstand different temperature fluctuations.
Diphyllobothriasis
Diphyllobothrioses is a dangerous helminthic disease of humans and carnivores caused by cestodes of the genus Diphyllobothrium. In Russia, the wide tapeworm Diphyllobothrium latum is found more often than other species.
The strobila D. latum has a length from 1 to 10 m. The scolex is devoid of hooks and has two deep bothria. The number of segments can reach up to 4000 pieces. The segments are short and wide, each segment has 3 genital openings (uterus, vagina, cirrus). The eggs are oval in shape, 0.068-0.071 by 0.045 mm, equipped with a cap at one pole. The egg contains a special embryo - coracidium, with 6 hooks.
The development cycle of the wide tapeworm occurs with the participation of intermediate hosts - crustaceans - Cyclops, Diaptomus, etc., and which is dangerous for humans with the participation of additional hosts - pike, perch, ruffe, burbot and other fish. Human infection with diphyllobothriasis (wide tapeworm) occurs by eating insufficiently heat-treated fish, by eating dried and insufficiently salted fish, when the technology for salting fish is not followed. Once in the human body, the helminth parasitizes in the small intestine. The parasite can live in the human body for up to 20 years or more.
From the moment of infection to the appearance of the first symptoms in a person, it takes from 20 to 60 days. The disease is accompanied by nausea, sometimes vomiting, abdominal pain, and a slight increase in body temperature. The disease is characterized by the development of B12 deficiency anemia, which manifests itself in a person with weakness, dizziness, fatigue, the development of swelling on the face and limbs, etc.
The diagnosis of the disease is made by medical professionals based on clinical and epidemiological data and laboratory test results.
Prevention. In order to prevent the disease, the caught fish is boiled, frozen in the refrigerator (they die at minus 15°C for 24 hours, at minus 4-6°C for 10 days), and salting technology is followed (the salt content must be at least 9%).
How to determine the presence of opisthorchid in fish
The causative agent of the disease is the Siberian fluke. This is a small parasite, 7-12 mm in size, living in the bile ducts, pancreas or gall bladder. Before reaching humans, the parasite is in the body of mollusks or freshwater fish, the carp family - they are an intermediate link in the chain of infection. It is impossible to identify helminths in a carcass due to its small size. Opisthorchis and its larvae are clearly visible under a microscope. But this diagnostic method is only available in the laboratory. Ordinary citizens, in order to avoid becoming infected with opisthorchiasis, need to know at what temperature worms in freshwater fish die, since the larvae mainly infect representatives of the carp family.
You can determine whether a fish is infected by external signs:
- the presence of spots, black spots, hemorrhages;
- dullness of scales;
- cloudiness of the eyes;
- abdominal enlargement;
- disproportionate sizes.
When catching such individuals, you must discard the catch, since the fish may be infected.
Opisthorchis
What fish have parasites?
People often wonder whether there are parasites in sea fish. It will be a discovery for many, but helminths are found not only in freshwater fish; there are also dangerous worms in sea fish and other seafood. In this case, a parasite can enter the body, which, in principle, does not live in this type of fish.
This happens as a result of large fish feeding on smaller fish. If you follow safe cooking techniques from seafood, all parasites die, and the dish becomes absolutely safe.
Only those who like to enjoy rolls, sushi and other treats that are prepared without heat treatment of the product take risks. They are at risk of anisakids, which will cause problems with the gastrointestinal tract, and subsequently provoke a stomach ulcer. Getting rid of parasites and the diseases they cause will require a lot of time, effort and money, is a piece of roll worth such sacrifices?
Parasites in pollock include Chinese fluke, Siberian fluke, broad tapeworm and some others. Red fish: pink salmon, salmon, chum salmon contain tapeworms, roundworms, cat fluke, phylometroidosis and others.
How to neutralize fish from parasites
There are several ways to neutralize fillets from parasites to avoid infection. Fish needs to be properly:
- cook;
- freezing;
- salt;
- dry;
- fry;
- stew.
Freezing kills the adult parasites and larvae. But this must be done correctly, since different types of helminths can die when exposed to cold for different durations. After freezing, the fillets need to be boiled or cooked to completely kill the parasites.
Freezing
A reliable way to neutralize carcasses is to freeze them. Almost no viable parasites are found in frozen fillets. Therefore, the caught fish (if it is not cooked immediately) is frozen. How long you should freeze fish to remove parasites depends on the temperature. The table provides the time and temperature for freezing raw materials weighing 2 kg.
| Time, h | Temperature *C |
| 12 | -27 |
| 18 | -22 |
| 36 | -16 |
| 72 | -12 |
| 7 days | -8 |
| 10 days | -4 |
Opisthorchids are killed by temperatures of -40*C for 3 hours and -30*C for 6 hours. The larger the fish, the longer it needs to be frozen. Small fillets less than a kilogram can be frozen at home in a regular freezer for at least 10 hours. To destroy the tapeworm, the fish should be frozen for a day. The deep freezing method is also used (keeping the meat for 3-4 days). If the chamber maintains a temperature of -12*, then the raw materials must be kept for at least 20 days.
Salting, smoking, drying
These are the most favorite ways to cook fish. In this form, it is brought as a gift, or bought when visiting fish markets. The effects of salt and smoke have been known for a long time. But this processing method does not always pay off. It is necessary to strictly adhere to the technology so that the finished product is safe for consumption:
- hot salting (16*C) – 5-9 days;
- cold salting (6*C) – 6-13 days.
Dry salting is done at the rate of 20% salt per 1 kg of fish. Gutted carcasses are kept in this mixture for 7-12 days, and whole carcasses for 9 to 13 days.
Cold or hot smoking kills all parasites by the time they are fully cooked. The fish is dried for 21 days. On the eve of the cooking process, the fillets are kept in a 15% saline solution for 72 hours.
Information! At home, it is difficult to smoke fish correctly, since it is impossible to maintain the desired temperature for a long period. Therefore, it is necessary to refuse to prepare raw materials in this way at home.
Boiling, frying, baking
Almost all river inhabitants contain parasites. Heat treatment is a simple and reliable way to destroy “undesirable residents” in meat. How long should you cook river fish to kill parasites, depending on its size. The larger the fish, the longer it is processed. This also applies to frying and baking. In order not to doubt the correct preparation, you should cut the carcasses, cut them into small pieces and cook for at least 30 minutes after boiling. Boiled fish is not dangerous to eat. How long should you cook sea fish to kill parasites? It must be prepared in the same way as river fish.
Fry the fillet under the lid. This will create a high temperature, and the parasites will be completely neutralized. The cooking time depends on the size of the product pieces:
- small fish – 10 minutes;
- 700-1200g, as well as fillets 2-4 cm thick, cook for 15-20 minutes;
- carcasses with a backbone or thickness of 5-6 cm are fried for at least 40 minutes.
Fans of pies with fish filling should bake them for at least half an hour. You need to bake the fillet in an oven, maintaining a temperature of 200*C for 35-40 minutes.
Methods for preparing fish
What does it eat?
The diet of burbot leaves no doubt as to whether it is a predator or not. It feeds on the inhabitants of the bottom layers. And if the fry consume zooplankton as food, the babies (individuals under 2 years old) eat mainly worms, caviar and fry of other fish species, caviar, small crustaceans and mollusks, then the menu of adult sexually mature fish already includes larger prey.
Which fish do you think tastes better?
- Salmon 41%, 288 votes
288 votes 41%288 votes - 41% of all votes
- Seabass 28%, 193 votes
193 votes 28%
193 votes - 28% of all votes
- Dorada 20%, 137 votes
137 votes 20%
137 votes - 20% of all votes
- Nelma 5%, 32 votes
32 votes 5%
32 votes - 5% of all votes
- Sea bass 4%, 30 votes
30 votes 4%
30 votes - 4% of all votes
- Whitefish 3%, 19 votes
19 votes 3%
19 votes - 3% of all votes
Total votes: 699
26.09.2019
- Salmon 41%, 288 votes
288 votes 41%288 votes - 41% of all votes
- Seabass 28%, 193 votes
193 votes 28%
193 votes - 28% of all votes
- Dorada 20%, 137 votes
137 votes 20%
137 votes - 20% of all votes
- Nelma 5%, 32 votes
32 votes 5%
32 votes - 5% of all votes
- Sea bass 4%, 30 votes
30 votes 4%
30 votes - 4% of all votes
- Whitefish 3%, 19 votes
19 votes 3%
19 votes - 3% of all votes
Total votes: 699
26.09.2019
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The list of what burbot eats includes different types of fish, including:
- smelt;
- minnows;
- loaches;
- perches.
They eat frogs and some crustaceans.
The answer to the question of whether the burbot is a predator or not is given by the features of its anatomy. Thanks to its wide mouth and throat, it can swallow prey alive, the size of which reaches up to a third of the length of the hunter’s body. This fish has a well-developed sense of smell, which fishermen take advantage of, using bait with a strong odor as bait, including a dead fry of perch or other fish. Experienced fishermen know: the predator does not disdain already dead fish, which has earned it the nickname “scavenger”. Such omnivory is more common in individuals living in water bodies depleted of fauna. The favorite dish of all that burbot eats is ruff.
Before spawning in winter, it can fast for up to a week, and already during the spawning process, the appetite of this predatory fish increases, so fishing is prohibited during this period.
Disease Prevention
In order not to “catch” helminthiasis, you must follow all the rules for preparing fish, as well as strictly adhere to personal hygiene.
- Buy fish only in special stores.
- Check the catch for the presence of “bad” individuals.
- During the cooking process, use dishes and kitchen utensils used only for fish.
- Do not taste raw minced meat.
- Cook large fish by cutting into portions.
- Maintain temperature conditions.
- If possible, reduce the intake of dried, lightly salted or raw fish.
These tips will help protect yourself from helminthiasis.
Fish parasites
There are also enough parasites in river fish; most often helminths can be found in grayling; it is not expensive, which means it is in demand among the population. When you cut a grayling, you can often see whiteworm in it. Often nematodes can be seen in the liver of crucian carp; helminth larvae look like small balls and are quite easy to see. However, in freshwater fish you can often find worms, which, although they look like parasites, are not parasites - these are freshwater leeches. With sufficient heat treatment, all freshwater fish parasites die. Parasites in river fish: Chinese fluke, trematodes, tapeworm, broad tapeworm, plerocycloids and others.
It is impossible to unequivocally answer the question of which fish are free of parasites; we can only say that helminths are less common in fish that live in the sea and even in those that swim in very cold water. However, it is impossible to name a type of fish that is not susceptible to helminthic infestations.
How to protect yourself from parasite infection
Knowing that fish can contain various parasites, you should adhere to the cooking technology, subjecting the fish to heat treatment. Such technologies include:
- Cooking.
- Frying.
- Hot smoking.
- Deep ambassador.
- Deep freezing.
If the fish is cooked for at least 20 minutes, then any type of parasites will die in it. If you fry fish, this is another fairly effective way to get rid of parasites, since the temperature is higher than when boiling. Hot smoking also allows you to neutralize parasites, but the duration of treatment should not be less than 2 hours.
In addition to temperature treatment, there are two more options that can protect a person from helminth infection - deep salting and deep freezing. Salt destroys all types of parasites within 2 weeks. If large fish is used for salting, then the processing time should be increased.
Parasites can also be destroyed by deep freezing at a temperature of -40 degrees. In such conditions, the parasites die within 24 hours. Before such a technological procedure, the fish is thoroughly washed under running water.
As you can see, there are enough ways to disinfect fish, so it is not problematic to use any of them.
Recently, it has become fashionable to eat fish without proper temperature treatment, since in such dishes most of the beneficial components, such as minerals and vitamins, are preserved. But then you need to be 100 percent sure that the fish meat does not contain parasites, otherwise healthy food will turn into serious health problems after some time.
Security measures
In order not to become infected with dangerous parasites (as you may have already seen, there are a lot of them in fish), a person first of all needs to give up the habit of eating the meat of aquatic inhabitants raw. Most often it is found in oriental cuisine, so despite the desire to enjoy the taste of the delicacy, it is best to abandon it in favor of traditional boiled or fried fish. Let's highlight some recommendations from professionals:
- A complete ban on adding raw seafood to the diet.
- Fish dishes should be cooked at temperatures above 60 °C for a long time. In this case, all helminths will die.
- Cold smoking and salting do not allow you to completely get rid of the parasites existing in fish, so it is undesirable to resort to them.
Sea fish must be frozen after catching, and then, once defrosted, cooked immediately. Its storage is highly undesirable. River fish should be cooked, boiled (at least 1/3 hour) or steamed, fried. Fish pies and pies are baked for at least 30 minutes. It is best to cut the meat into small pieces. Advice to housewives: you should not try uncooked fish meat while preparing a dish.
It must be remembered that in most cases, helminth larvae are not visible to the naked eye, so if a person does not notice them, this does not mean that they really are not there.
To prevent the possibility of this disease occurring, you need to follow several rules and recommendations.
Avoid the need to eat raw fish, and this applies to freshwater and marine representatives. It is also necessary to limit the consumption of seafood and always adhere to careful thermal processing.
Usually, if an individual has passed the infection stage, it has an unattractive appearance, as well as a weak muscle structure, when you click on it, you will notice a hole.
It is necessary to remove all the insides without exception and thoroughly rinse the fish under running water, this will wash away the bacteria and avoid general poisoning of the body from fish meat.
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Measures aimed at preventing infection
In most cases, helminths from fish occur in adults. This is explained by the fact that special importance is attached to preparing dishes for children, so they carefully monitor the sufficient level of heat treatment.
The best thing for you and your health is to avoid eating raw fish, the origin of which is unknown to you. Otherwise, it may cause parasite infestation.
At the same time, there is a list of fish that you can eat without any fear. This list includes:
- fish that were fed in artificially created conditions with monitoring of their health;
- fish that are classified as sturgeon (for example, sterlet);
- sea fish that was frozen immediately after catching - this frozen product must be thawed immediately before preparing dishes from it.
The main emphasis in preventive measures is the correct preparation of fish and dishes made from it. Separate knives, boards and utensils should be used, which after work are washed and treated with boiling water.
When preparing fish dishes, you need to follow several recommendations.
- Heat treatment will help kill parasites. It should be carried out as follows:
- the fish is cooked for at least 20 minutes from the moment of boiling;
- fry - also for at least 20 minutes under a closed lid;
- baked goods filled with fish are prepared for at least 30 minutes in the oven or oven.
- If fish is prepared by cold or hot smoking, then all the parasites in river or red fish die even before cooking is completed.
- You can kill worms by freezing:
- at a temperature of -27 degrees, the freezing duration should be 12 hours;
- if the temperature is -22, it will take at least 18 hours;
- at a temperature of -16 degrees, the duration of freezing is two and a half days;
- if the temperature in the freezer is -12 degrees, then it will take 3 days for the parasites to die;
- You need to freeze the fish at a temperature of -8 degrees for a week;
- It will take 10 days for the helminths to die if freezing is carried out at a temperature of -4 degrees.
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But these indicators are suitable if the amount of fish does not exceed 2 kg. If the weight of the fish is large, the freezing period must be increased.
- When fish are salted, parasites die:
- 5 days in case of hot salting;
- 6 days with cold salting;
- 9 days in case of dry salting, but if the fish is uncut;
- per week in case of dry salting of cut fish.
These indicators are considered correct if the percentage of salt is at least 20% of the weight of the fish.
