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Joanna Tkaczewska, Piotr Kulawik, Wladyslaw Migdal ®
University of Agriculture in Cracow Departament of Food Technology, Poland
NUTRITIVE VALUES OF TROUT, CARP AND STURGEON.
THE COMPARISON.
Abstract
The item of the research was the three species of fresh-water fish : trout, carp and sturgeon. The fundamental chemical composition designated by typical methods for each nutritive component. Estimated the nutritive components content in the flesh samples of mentioned above fishes. The highest concentration of protein and minerals was discovered in the meat of trout. The lowest one in the meat of sturgeon. The meat of carp was discovered as the biggest source of fat. Key words : carp, trout, sturgeon, nutritive values Introduction
Fish and all kind of fish-products are very precious source of many essentials nutritive components. Poland is one of the European countries which have the lowest level of fish consumption per one inhabitant. It is the result of weak promotion and constant lack of information about the fish and fish-products exceptional values [ Z. Usydus, 2008 ].
For last 10 years the consumption of fish meat in Poland increased 2 % only. In spite of this upward tendency it is really hard to speak about a favourable economic prognosis for fish breeders. According to The Agriculture and Provision Economy Institute an average Pole eats about 3,37 kg of fresh-water fish (the consumption of trout is only 0,4 kg a year).
Trout, carp and sturgeon are the three of fresh-water fish bred or fished on the polish territory.
Trout, as a bred fish has a special economical meaning particularly in southern Poland. Trout is a obligatory predator as majority of salmon species [Brylinska 2000, Allan 1998, Kara 2005]. They feed on animal seston [Frankiewicz, 1993 ] on bentos [Steingrimsson, Gislason 2002] and vertebrates. They are also cannibals.
The trout farms were estimated as those which are in the best condition in comparison to the other fresh-water fish farms in Poland. Between the years 2002 and 2006 thr production of trout increased about 40%. The main factor that stimulates this increase is export of trout to the European Union countries. It is about 30% of the general production ( for example the export of carp is about 1% general production ) [Lirski 2008].
Carp is bred for hundreds years in polish ponds [Sikorski Z.E.,2004]. Through all those years the bred methods with policulture with other species have changed and constantly improved. But still the farmers managed to keep a traditional character
® Joanna Tkaczewska, Piotr Kulawik, Wladyslaw Migdal, 2010
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of the system. The main attributes of this system are: the several-years production cycle depending on climatic conditions, the natural food naturally developed in the pond, using in breeding mainly not processed cereal, low level of production intensify
- it has not exceeded 700-1000 kg/ha.
The biggest conglomeration of carp ponds is situated in the southern Poland [Szczebrowski, 1993]. Since the beginning of XXI century we can see the constant decrease in carp production. It has of course the big influence on economical state of pond-farms. It was estimated that the carp fishing between the years 2002 and 2006 decreased from 21 400 tons to 15 574 tons. This is almost 30% less [ Lirski 2008].
Sturgeon is two-environments fish. For the procreation this species choose the rivers, for haunting choose the sea. As a result of very intensive fishing, the pollution and unfavourables changes of hydrologic conditions (the dams) this species was almost completely exterminated.
Sturgeon is a predator. Majority of his food are little water animals living by the bottom.
Sturgeon has a big economical meaning because of tasty meat and very exceptional spawn. As a result his price is rather high [Sikorski Z.E. 2004].
The meat of fresh-water fish has tremendous nutritive values [Sikorski Z.E., 2004]. It is a perfect source of protein, vitamins, micro and macro-elements, and above all polyunsaturated fatty acids [Kolakowska A., Kolakowski E. 2000]. It appears that the fresh-water fish have the same big participation in WNKT among the fatty acids as many species of sea fish. There are a lot of new thesis that the meat of fresh-water predators has much less cholesterol but more of polyunsaturated fatty acids ( which as f.ex. linol and arachidon acids are essential for human beings ) then non-predators. The profile of fatty acids is still the same [Bieniarz K. , 2001]. The fat of some fresh-water fish includes a lot of fosfolipids, descended cholin. It is suspected to have the big influence for men's health : it prevents the concentration of cholesterol inside our blood-vessels. The fresh-water fish is also the source of many minerals as potassium, phosphorus, calcium, selen and iodine. It is a source of vitamins as D, E (dissolving in fat) and PP, B2, B6, B12 (dissolving in water).
The aim of work
The aim of this work was researching the content of nutrition components in the meat of trout, carp and sturgeon. The range of this work includes: marking a dry mass, mineral remains, protein and fat.
Materials and methods
The material to the research were the filets taken from the fishes from the same source. The slaughter was made by decapitation after stunning. The filets were prepared by hands. Than the samples was taken from the filets and minced. After that in the samples marked : the content of dry mass, mineral remains (ash), protein and fat. The dry mass was marked by drying the sample till the constant weight in a dryer
- 105 C. degrees. The mineral remains were marked by combustion the sample in 550
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c degrees. The protein in the samples of fresh meet was marked according to Kjedahl method. The fat was marked according to Soxhlet method. Results of researches Dry mass
In raw meat of water animals the water is the main component : 50-93% depending on species [Z.E. Sikorski, 2004]. The research showed the biggest content the dry mass in the sturgeon meat samples ( 29,22% of dry mass ), afterwards in the carp meat samples ( 27% of dry mass). In the surgeon meat samples was discovered the biggest content of water ( 26,83% ). The mentioned above results are showed on the following graph 1.
Graph 1. The dry mass content in the meat of trout, carp and sturgeon
Dry Mass
29,50% 29,00% 28,50% 28,00% 27,50% 27,00% 26,50% 26,00% 25,50%
Trout Carp Sturgeon
The dry mass is the content of carbohydrates, protein, fat, minerals and vitamins in general [ Fortuna, 2003 ]. That is why the quantity of the dry mass is proportional to the nutritive values of the item. In this case it appeared that the most valuable is the meat of trout.
Protein
In the samples taken from the muscles of this three species marked the protein content between 19,44% and 17,51%. The biggest content of protein was discovered in the meat of trout. The lowest one in the meat of sturgeon. The mentioned above results are showed on the following graph 2.
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Graph 2. The protein content in the meat of trout, carp and sturgeon
The protein is the most precious content of fish meat - both sensor and biological meaning. Content the protein in the bodies of these organisms is alike to the content of it in the bodies of slaughter animals. It is about 13-24%. Only 3-5% is the worthless tissue protein - 16% in the meat of slaughter animals [Borucka, Wieczorek 2003].
The protein in these three samples have very alike level. But the biggest content of protein has a meat of trout ( 19,44% ), a little less in a meat of carp (18,36% ). The sturgeon is the poorest source of protein (17,51% ).
The content of protein is directly correlated with the content of dry mass.
Fat
As a result of research estimated the biggest content of fat in the meat of carp ( 11,39% ). Considerably less of it contains the meat of sturgeon (7,69% ). The meat of trout appeared to be the leanest ( 4,97% ).
The results are showed on the following graph 3.
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Graph 3. The fat content in the meat of trout, carp and sturgeon
Fat
12,00% 10,00% 8,00% 6,00% 4,00% 2,00% 0,00%
Trout Carp Sturgeon
Carp and sturgeon are included to fat fishes ( the fat content between 8-18% ). Trout is lean one ( the fat content under 5% ). The more content of fat in meat the more content of polyunsaturated fatty acids in it. On the other side the big content of lipids means the big energetic value of a product. And it can be considered as a negative feature [Swiderski, 2003]. Anyway, the meaning of the fish meat in men diet is concerned generally with the content of polyunsaturated fatty acids omega-3 [Kolanowski, Powierza 2008]. That is why we can say that the meat of carp is the most valuable. Ash
The results considered with content minerals in the meat of trout, carp and sturgeon did not exposed the considerably big differences between them. The difference between the highest level ( Trout - 1,43% ) and the lowest one ( sturgeon -1,05% ) is only 0,38%.
The results are showed on the following graph 4.
As a result of ashing row material of fish one gets usually about 0,6 - 1,6% of ash. It contents every useful micro and macro-elements [Borucka, Wieczorek 2003]. The meat of fish is much better source of roots in comparison to another animals. Additionally small fish-bone species and fish marinates provide a lot of calcium [Gaw^cki, Hryniewiecki 2005].
Trout is the richest one as to the minerals - 1,43%, a little less is meat of carp-1,22%. The poorest in minerals is sturgeon - 1,05%. But every of the three species content much of minerals so they can be a good source of ash in men diet.
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Graph 4. The ash content in the meat of trout, carp and sturgeon
Ash
1,60% 1,40% 1,20% 1,00% 0,80% 0,60% 0,40% 0,20% 0,00%
Trout Carp Sturgeon
Conclusions.
1. The meat of trout contents the less water in comparison to other researched species. That's why we can say trout has the highest nutrition value. Its meat is also the richest source of protein and minerals. But its meat is the poorest in fat.
2. The meat of carp is the richest source of lipids. It is also quite good source of proteins and minerals.
3. the meat of sturgeon has the worst nutrition value in comparison to trout and carp. It contains the most quantity of water what makes it very poor in another nutrition components.
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