Iodine rich seafoods

Iodine is found in a range of foods, the richest sources being fish and dairy products. The most important natural source of iodine in the human diet is from marine fish and other seafood products. Fish such as cod and tuna, seaweed, shrimp, and other seafood, are generally rich in iodine.

Seaweed is a concentrated source of iodine, but it can provide excessive amounts (particularly so in the case of brown seaweed such as kelp) and therefore eating seaweed more than once a week is not recommended, especially during pregnancy. White fish contains more iodine than oily fish.

The study by Institute of Nutrition, Directorate of Fisheries showed that the iodine concentration in fillet of salt water fish was 5 to 10 times higher than those of fresh water fish, with highest value of 920 μg I/kg wet weight for changu. The lowest iodine concentration in fillet was found in barbus from Lake Awasa with only 5–8 μg I/kg wet weight. The iodine concentration in skin was higher than in fillets and the iodine concentration in fillets seemed to increase with fish size. The samples of plant origin were, in general, low in iodine (Journal of Food Composition and Analysis Volume 10, Issue 3, September 1997, Pages 270-282).

Iodine is an essential micronutrient required for normal thyroid function, growth and development. Its deficiency and excess both have adverse consequences on the body through effects on the thyroid gland. The thyroid gland requires trapping about 50-75 micrograms (μg) iodine daily to maintain an adequate supply of thyroid hormones. When daily iodine intake is below 50 μg threshold, goitre may develop.
Iodine rich seafoods

Flavor of seafood

Very fresh fish are characterized by mild, delicate flavors and aromas that are contributed by volatile 6-, 8-, and 9-carbon carbonyls and alcohols arising from the action of lipoxygenases on long-chain polyunsaturated fatty acids.

The characteristic aroma and flavor of very fresh fish and other seafoods are characterized by their specific taste, flavor and sometimes by texture, which in general are referred to as 'sensory attributes'. Sensory attributes of the processed fish and fishery products are important criteria for consumers preference.

The specific taste of each food relies on extractive components which are defined as water-soluble, low molecular weight components, and classified into nitrogenous compounds (free and combined amino acids, nucleotides and related compounds, organic bases etc.) and non-nitrogenous compounds (sugars and organic acids) with the exception of vitamins, pigments and minerals.

The early studies on the flavor chemistry of fish were on the identification of flavor components of a particular species of fish. Some investigations had been done on the quantification of flavor components.

The umami taste of the Chinese mitten crab’s meat is significantly contributed by glutamate, IMP (inosine 5’-monophosphate) and AMP (adenosine 5’-monophosphate).

AMP imparts umami taste to the muscle of squid. It was reported trimethylamine oxide (TMAO) and trimethylamine (TMA) as taste-active components in squids. These TMAO and TMA contribute to sweetness and an agreeable characteristic squid flavor, respectively.

The flavor of prime salmon results in part from the co-oxidation of carotenoid pigments and polyunsaturated fatty acids which yield characterizing aroma compounds.

It was reported the contribution of sodium and chloride ions to the taste of snow crab. In addition to these, some inorganic ions such as potassium and sodium could contribute salty taste to Chinese mitten crab meat flavor.

During processing, thermal degradation, lipid oxidation and Maillard reaction may play important roles in generating complicated volatile compounds contributing to the processed shellfish flavor.

Flavor quality deterioration in fish is caused by microbial activity and endogenous enzymic activity which results in the destruction of some compounds and the formation of others.
Flavor of seafood

Zoonotic disease of Anisakiasis

Anisakiasis is an infection by the larval stages of ascaridoid roundworm Anisakis simplex from the family Anisakidae of the order Ascaridida.

Epidemiological studies conducted in Japan, have shown that cases of anisakiasis were likely to be encountered in coastal areas where individuals were involved in the fish industry.

Cases in Europe, the United States and elsewhere also appear to be on the rise, but are more likely the result of culinary habits associated with ethic groups or restaurants.

The adult Anisakis spp, inhabits the stomachs of sea mammals, such as small whales, dolphins, and seals, and passes eggs with feces into the oceans. Larvae hatch and are ingested by tiny crustaceans, which become infected and are in turn eaten by fish and squid.

The larval stage is found in a wide variety of fish, of which herring cod and the Alaskans Pollack are the most significant for human infection because they are most frequently eaten raw.

Humans are accidentally hosts in the life cycle of anisakid nematodes and although the parasites almost never develop further within human alimentary tract they may penetrate the tract and associated organs, with severe pathological consequences.

Ingestion of Anisakis larvae with seafood is often responsible for acute allergic manifestations such as urticaria and anaphylaxis, with or without accompanying gastrointestinal symtomatology.
Zoonotic disease of Anisakiasis

Shellfish species of surf clams

The surf clam or ‘skimmer’ is large, reaching a length of 8 in, (20.3 cm). It is found just below the surface of sandy bottoms in waters 30 to 100 ft (9 to 30 m) deep off Atlantic Coast states from Massachusetts to including Virginia.

Areas of coarse grain size (i.e pebbles or cobbles) are virtually devoid of surf clams. Atlantic surf clams are planktivorous filter feeders that pump water through their siphons over the gills to trap foods.

Many predators, including snails, shrimps, crabs, and fish –haddock and cod, feed on surf clams.

Maximum age exceeds 30 years; surf clams of age 15-20 years are common in many areas. Surf clams are harvested when they reach 4 inch (10 cm) which occurs at about 5 years of age.

Currently, commercial concentrations are primarily found off of the New Jersey shore, the Delmarva Peninsula, and on Georges Bank.

Most of harvesting this species is done off New Jersey with water-jet dredges having V-shaped scoop. Aboard the boats, the clams are placed in baskets or jute bags and brought to the processing plants without refrigeration.
Shellfish species of surf clams

Cholesterol content in seafood

Cholesterol is the main sterol in marine fish like haddock, pollock, salmon and in crustaceans like shrimp and lobster with over 90% of all sterol.

The cholesterol content in fish and mollusks ranges from 40 to 100 mg/100g portion and is lower than other meat such as beef, pork and chicken.

Lower cholesterol content was reported in ground fish and pelagic fish species, higher content in mollusks and crustaceans.

The shellfish, shrimp and prawns, however are quite high in cholesterol 195 mg/100 g portion of shrimp. 

Fish, particularly deep sea fish such as salmon, tuna, haddock, sole and swordfish are good source of protein with cholesterol content comparable to buffalo.

Cholesterol content in single species of fish can vary widely at different times of the year, at different growth stages and in different reproductive stages.

In fish, cholesterol biosynthesis is controlled in the liver and intestines by means of feedback mechanism as in mammals.
Cholesterol content in seafood

Uric acid and seafood

Uric acid is a weak acid (pKa=5.8) that exists largely as urate the ionized form, at physiological pH. In general, the risk of supersaturation and crystal formation rises in parallel with concentration of urate in physiological fluids.

Uric acid is the end product of the degradation of chemicals called purines and hyperuricaemia can result from overproduction of or reduced excretion of uric acid through the kidneys.

Studies have shown that eating a diet heavy in high purines seafood has been linked to higher serum uric acid levels and increased future risk of gout, which is likely due to its high purine content.

Foods high in purines include, anchovies, caviar, sardines, mussels and herring.

High uric acid is associated not only with gout but many other illnesses. People in the highest quarter of blood uric have three times the coronary heart disease death rate compared to those in the lowest quarter.
Uric acid and seafood

Seafood biological safety

Seafood is known to act as a vehicle in the transmission of a variety of human diseases. Proper storage of fresh and frozen seafood is critical to ensure its quality.

Preservation of fish typically takes the forms of curing, chilling, or freezing, canning and the making of mince or surimi.

Irradiation has been used in mackerel and may be used in combination with other preservation methods to, this should be to enhance shelf life and safety.

Due to globalization, seafood is being consumed further away from where it is harvested. In this case seafood market has serious food safety implications.

Current industry guidelines dictate that all those in the supply chain follow a HACCP which is systematic preventive approach to identifying possible food safety problems.

Seafood handlers must continually invest resource in the effective control of pathogens in order to protect consumers.

The biological hazards associated with seafood as a disease vector can be roughly grouped into bacteria, viruses, parasites and marine toxins.

Viruses, parasites and marine toxins pathogenic to humans are mostly present in the seafood prior to harvest.

Biological hazards include Clostridium botulinum, Listeria monocytogenes, salmonella and pathogenic staphylococcus.

Seafood biological safety

Seafood can cause Gout

While seafood may be healthful for many, some choices can be quite harmful to individuals with gout.

There is small but significant association between incidence of gout and increased consumption of seafood.

What is gout? Gout is considered a form of arthritis that may benefit from anti-inflammatory diet that restricts saturated fat and sugar and includes omega-3 fatty acids.

People with gout suffer from joint pain caused by a buildup of uric acid.

Uric acid is the end product of the degradation of chemical called purines. The diet most often recommended for gout restricts purines.

Purine is one of uric acid component.

Most of our own purines are recycled for re-use by our cells. The problem is that our food contributes to purines, which are broken down immediately in the gut membranes to create uric acid before transported in the blood to the kidney.

If the level of uric acid raised in the blood due to purine rich food like seafood is taken rapidly where no more can be dissolved, crystal will form.

Crystal will be deposited in joints and soft tissue, where they cause local mechanical pressure and acute or chronic inflammation.

In the early stages, gout is characterized by episodic attacks of joint inflammation, which are usually monoarticular (affecting one joint) and begin abruptly with intense pain, swelling, warmth and redness of the affected joint.

Purines are most concentrated in seafood and shellfish. Seafood ahs some of the highest purine content, especially sardine, anchovies, salmon and herring.
Seafood can cause Gout

Methods That Keep Seafood Alive

Methods That Keep Seafood Alive
The trapping techniques certainly provide the best opportunity for the fisherman to land and supply the freshest highest quality product. When an animal becomes trapped in a closed area, it remains alive and untouched until it is removed. Therefore, as long as the traps are judiciously operated and emptied on a reasonably cycle the seafood is removed and slaughtered just prior to sale or use.

An excellent example of the use of traps (pots) is the crab industry. In fact, most crabs must be butchered while alive in order to ensure that the meat is well bled. Otherwise there will be a “blueing” of the meat. This is due to the blood chemistry of a crustacean.

While most animals have a heme (iron) complex in their blood, crustacean have a copper complex. When the blood is not removed prior to processing, the copper oxidizes, giving the giving the white crabmeat an unsightly blue color. Although the basic nutritional value is not impaired, the sensory-oriented consumer does not like and will not purchase blue colored crab.

The ultimate in retaining live fish and shellfish in containers or penned areas is found in fish farming or aquaculture. In this case, the raw materials are raised throughout their life cycle in captivity in a normal farming type operation.
Methods That Keep Seafood Alive