Ancient populations that inhabited islands and coast lines mainly lived off fish and this food, along with fruit and cereals, made up the initial ‘Mediterranean diet’. Even today, fish is still considered an important food for millions of people due to the fact that 70% of the world is covered in water and this is where a great source of protein can be found. The composition of fish is very interesting from many points of view, especially a nutritional one as it an be eaten by people of all ages.
The water content in fish varies and can range from 60-80% with an inverse proportion of fat content (lipids). 15-25% is made up of proteins, however, low fat fish contain significantly more and fatty fish contain less. There is more myofibrillar protein present in fish muscle than there is in the muscle meat that comes from warm-blooded animals, furthermore, the content of connective tissue is low and the muscle fibres are short and are layered in so called myotomes.
The smell of ‘not fresh fish’ is caused by a particular substance called trimethylamine N-oxide (TMAO), which is present in fish as a soluble, nitrogenous compound which, after the animal dies, turns in to trimethylamine (TMA) or methylamine (MMA) and formaldehyde due to bacteria, creating that unpleasant smell.
As far as fats and lipids are concerned, their content varies from 0.5-22%, depending on the species, how the fish are bred, what they eat and how they are caught.
Fish can be divided into these categories:
Low-fat: (containing less than 3% lipids) for example, anchovies, hake, cod, sole, trout and pike;
Semi-fatty: (containing 3-8% lipids) for example, bream, grey mullet, mullet and sardines;
Fatty: (containing more than 8% lipids) for example, eel, mackerel and salmon.
It must be mentioned that the fatty acids found in fish are different from those
found in meat, for example, the famous Omega 3 fatty acids, the progenitor of
which is alpha-linolenic acid, can be found in fish, including EPA (eicosapentaenoic
acid) and DHA (docosahexaenoic acid), and there are more of them than Omega 6
fatty acids. Omega 3 fatty acids are very important for vasodilator and antithrombotic
There are few carbohydrates present in fish, the percentage of which is 0.5-1%. Minerals can be found in fish though, particularly phosphorus, calcium and iodine, and the most common vitamins found in this food are vitamins A, D, a small amount of B vitamins and vitamin PP, which oily fish are very rich in. Mussels are very rich in iron, as are oysters.
Fish is very easy to digest (of course the less lipids, the easier digestion is) and the low amount of connective tissue means that it is metabolised very quickly, as well as the composition of noble proteins making it an important part of our diet. Nutritionists recommend we eat it 2-3 times a week instead of meat, eggs, pulses and cheese. Thanks to its low purine content, it can even be eaten by those who follow a special diet, for example hyperuricaemic patients.
Which fish for which age?
Fish is a healthy and digestible food and, as well as other types of meat, it is introduced when weaning children. Of course the leaner the fish the better it is for babies, whilst adults can eat all types of fish (but not too much fatty fish). Elderly people should follow the same rules as young children by sticking to low-fat fish cooked in a simple and light way.
Fish, along with other foods, is subject to precise guidelines if it is to be sold and consumed. The label allows customers to see what they are buying and, amongst the other information on frozen foods, there must be information about the net weight of the glaze applied to the fish.
The information that must be on the label, by law, varies by country but it is mainly:
- the commercial name, or actual name, of the species of fish;
- the scientific name of the fish (optional);
- production method (if it was bred or caught);
- the catch area (where it was caught).
The catch areas are:
|Atlantic, North-West||FAO zone no. 21|
|Atlantic, North-East||FAO zone no. 27|
|Baltic Sea||FAO zone no. 27 IIId|
|Western central Atlantic||FAO zone no. 31|
|Eastern central Atlantic||FAO zone no. 34|
|South West Atlantic||FAO zone no. 41|
|South East Atlantic||FAO zone no. 47|
|Mediterranean Sea||FAO zone no. 37.1, 37.2, 37.3|
|Black Sea||FAO zone no. 37.4|
|Indian Ocean||FAO zone no. 51 and 57|
|Pacific Ocean||FAO zone no. 61, 67, 71, 77, 81 and 87|
|Antarctic||FAP zone no. 48, 58 and 88|
The various labourers who work in this sector must ensure traceability, which is very important in this specific sector, and they are subject to checks by the relative national authorities.
Here is an example of some of the information you might find on a fish label:
|1) Name of species||Sea bass|
|2) How it was caught||Fish farming|
|3) Country where bred||Italy|
|4) How to store||In fridge at 0-2°C|
|5) Expiry date||Consume by (date)|
Traceability and retraceability in fishing
Some of the aforementioned terms must be clarified as they are often confused and thought of wrongly, especially traceability, also known as tracking, and retraceability, also known as tracing, at an international level.
Traceability means the specific process that follows a product from the very beginning of the process chain. Traces, or information, must be recorded during each step of the process. Retraceability, or tracing, is the process in reverse, so from end to beginning which collects all the information in reverse.
In the fishing industry, traceability of the process chain is an essential instrument used to improve the whole supply chain and classify the final product. There are various people involved in chain from manufacturers, distributors, logistic companies, wholesalers, supermarkets and retail stores.
The necessity to trace the information regarding the fishing process was born out of the initiatives of associations all along the process chain, such as trade associations and protection consortiums. With regards to retraceability, this is a tool which enhances the relationship between producer and consumer.
The most common scams in this sector are:
- frozen fish sold as fresh fish (which is actually illegal unless it is strictly stated on a label next the fish so that the - customer is informed and therefore knows that that type of fish cannot be refrozen and must be consumed straight away);
- fish farmed fish sold as fish just caught at sea;
- selling one species as another species (the most common case is selling squid as calamari).
The main characteristics of aquaculture fish
Fish farming can be split up into the following categories:
- intense aquaculture: fish are bred in huge tanks (in fresh, salt or brackish water) and they are feed specific artificial feed, which depends on the type of species that must grow and survive. A particular type of intensive fish farming is mariculture and this is when fish live in huge cages that float in the open ocean;
- extensive aquaculture (valliculture): this is when fish eat normally, consuming only what the environment naturally supplies. They live in lagoons and coastal ponds;
- semi-extensive aquaculture: this is when the fish are feed a diet made up of 50% artificial feed and 50% what they find naturally in their habitat.
Nutritional values of aquaculture fish
The nutritional values of a fish farmed fish are generally the same as those caught at sea, however intensive aquaculture fish can have a higher lipid content compared to ‘free’ fish. Amongst the economic advantages is definitely the possibility to reduce waste as you only fish the amount of fish that has been ordered. The artificial feed is mainly made up of flour and fish oil (50-80%), which comes from low quality commercial fish. A small part of the feed is made up of vegetable proteins, such as soya powder. Meat powder is illegal.
Fish and allergies
Fish allergies do exist but crustacean allergies are more common. The main symptoms are hives, general itching, diarrhoea, nausea (gastrointestinal symptoms) and can even go as far as asthma attacks, headaches, and in the most serious cases, anaphylactic shock. The most allergenic crustaceans and shellfish are: crab, lobster, shrimp, clams, oysters, scallops, mussels, calamari and sea slugs. The most allergenic fish are: salmon, herring, swordfish, tuna, halibut and cod.
The new rules around fishing
From the 1st June 2010, the Mediterranean Regulation came in to place and it means we have to say goodbye to cuttlefish, clams, squid, fried seafood platters, whitebait and goby.
According to new requirements set out by the European Commission, as far as fishing in the Mediterranean is concerned, new and rigid distances have been established for fishing with a net from the coast, in order to protect species that are at risk, such as clams and razor clams.