Posted on 9th Oct 2024 09:10:32 AM Fisheries
INTRODUCTION
Bangladesh with its vast freshwater areas which include the great Padma, the Jamuna, the Meghna and their innumerable tributaries, is one of the richest areas in this sub-continent in respect of freshwater fishery. In addition the countries blessed with innumerable ponds and hundreds of natural depression known as ‘Beel’, ‘Haor’, ‘Baor’ etc.
Bangladesh is enriched with about 262 freshwater species (native) and 12 exotic fresh water species. Fish production in Bangladesh has been estimated to be 27.01 lakh mt. (DoF, 2010).
Fishes form one of the most important food items for human beings throughout the world. They are rich source of proteinous food and are consumed by all grades of people, rich and poor. They shape life of consumers because of containment of many valuable items, such as proteins and amino acids. In Bangladesh they are in high demand by common people and are oftenly available in the market in plenty.
Association of fish with the human beings has been from the time immemorial. They knew by experience that fish was palatable item of digestion and was good for health. Now scientific investigations have provided adequate knowledge of high quality of fish flesh in the sense of containment of proteins, fats and vitamin A and D, phosphorus and some other elements which stimulate for good health of the consumers. For having good taste and easily digestible nature, fishes are caught in large numbers and marketed so that they can be easily available to consumers.
The principal freshwater fishes consumed as food in Bangladesh are (i) the major carps like Catla catla, Labeo rohita, Cirrhinus mrigala, silver carp, grass carp and common carp, (ii) herrings like Hilsa ilisha, Gadusia chapra, Septipinna phasa, (iii) Catfishes like Mystus sp, Wallago sp, Pangasius sp., (iv) live fishes like Clarias sp, Channa sp., Anabas sp., some other fishes including Tilapia, etc.
Fish as food is composed of following nutrients:
a) Proteins, which provided energy needed by the consumer’s which provided energy needed by the consumer’s body during various metabolic processes and material for growth and repair of tissues and sometimes also for the formation of fat.
b) Carbohydrates in the form of glycogen in liver which provide the consumer body with energy and also produce fat.
c) Fats which provide energy and produce fat in the consumer’s body.
d) Mineral substances which provide material for growth and repair of tissues and for regulation of body processes.
e) Vitamins and other accessory substances, which regulate the body processes for various functional activities.
Fish as food, because of richness in proteins, minerals and vitamins, provide the nutrients essential for regulating the body processes and protecting the body. The fish is considered as one of useful source of several minerals, especially if the bones are consumed. The liver of fish provides vitamins A and D. Fish is also rich source of vitamin B.
Nutritional composition is the proportion of water, protein, lipid, carbohydrate, ash, moisture etc. present in the fish body. The composition may vary according to different size groups (include sub adult, adult, brood etc.) and body parts (include muscle, viscera etc.) of same fish species. Proximate composition varies greatly from species to species (Kamruzzaman, 1992).
As the fish grow, particularly in the maturation stage in large size fishes like carps and catfishes, considerable changes occur in the chemical composition. It seems that the quality of food which the fish consumes also greatly influences the chemical composition. In Clarias batrachus, for example, adults take more nutritive food in the form of insects, shrimps, worms and algae while the fry and fingerling mainly feed on protozoans, small crustaceans, rotifers, etc. comparative studies on nutritional values of different food items have shown that the fish proteins resemble chicken protein in values but are superior to beef protein, milk and egg albumen. Fish proteins contain all the ten essential amino acids which account for high biological value of fish flesh. The flesh of fish contains, besides proteins, also minerals, vitamins, iodine and fat. The demand for fish is high because of these qualities and also in consideration to the fact that fish offers a palatable taste and flavour and is easily digestible. All these qualities are in super condition in fish flesh. In preserved condition of fish, the flavour and even the biochemical composition undergo noticeable changes. Nevertheless, some fishes show considerable changes in their biochemical composition in respect to fishing ground, fishing season, time of collection, age, and sex of the fish. It has been marked that fat and water content are most affected, as evident from data on biochemical composition.
Biochemical Composition of Fish
The main biochemical contents of fish flesh are proteins which constitute 20%. Fat and water are also present but they vary widely and, at the same time, inversely. Minerals, vitamins and enzymes are also present in substantial quantity, but the carbohydrates do not occur in muscles except as glycogen in the liver. Water content shows variation from 55 to 83 percent. This figure is on higher side obviously due to aquatic habit of life. On the other hand the birds and mammals show much lower figures due to their terrestrial habits of life (Shafi, 2003).
Protein
The fish protein occurs as (i) intracellular components of muscle fibre, such as myosin, myogen, myo-albumin and globulin, (ii) collagen and connective tissue fibres, and (iii) phosphoproteins and nucleoprotein. The connective tissue content is 3-5% only. This property renders the fish protein more digestible than meat and, on average, 90 to 95% fish protein is assimilated by men.
The digestibility of protein varies from species to species. Histidine in particular, which is largely concerned with the flavour of fish flesh is in a sufficient quantity.
The skeleton muscles represent bulk of fish flesh, constituting about 50-60% of the total weight of fish. Both red muscles and white muscles are present, there being exclusive presence of myoglobin in the former. Another point of difference in the two kinds of muscles is in respect to the presence in larger quantity of glycine, leucine, arginine and phenylamine in the red muscle, whereas white meat contains more of lysine, aspartic acid and glutamic acid.
Regarding muscle properties, another point of consideration is that protein content of the muscle, on extraction by soluble fractionation, can be classified into 3 distinct groups:
1) Albumin fraction of which 16 to 22% are contained in sarcoplasm and interstitial fluid. These are extractible with weak salt solution (ionic strength less than 0.3).
2) Protein fraction of which 75% are contained in contractile elements (skeleton muscles). These are extractible with strong electrolyte solutions (ionic strength greater than 0.5).
3) Stroma, containing 3% in myocommate, cell membrances and connective tissue, extractile with difficulty. The fish muscle differs from the mammalian muscle in its very low content of stroma proteins, being 3% instead of 16%.
The basis of these three kinds of proteins in muscle is such that reportings on percentage figures, whatsoever, cannot be regarded as final. n fact, the application of modern techniques of electrophoresis and ultracentrifugaton have revealed the containment of a number of sub-fractions in each fraction. The fish muscle proteins also differ from the mammalian muscle in their very low content of connective tissue and in their content of albumins. There is also a remarkable difference in stroma proteins of fishes belonging to elasmobranchs and teleosts.
It has been found that the albumen fraction of fish muscle consists of at least six components. On the other hand protein fraction of the contractile element usually consists of actin, myosin, actomyosin and tropomyosin sub-fractions. These sub-fractions possess characteristic distinctions in respect to their sedimentation constant, diffusion constant, electrophoretic mobility and in other features.
There seems to be a direct relationship of fish diet with the biochemical composition of fish, particularly with the protein contents. Thus planktophasgous fishes have higher protein content than other feeding group of fish. Likewise, the cultivated fishes have higher protein content than the wild fish of the same species.
The fish flesh possesses a number of non-protein nitrogenous components. The main such items are: (i) Peptides, which yield flavour to prepared fish flesh. (ii) Free amino acids of which histidine is important. It has been found that the red muscle is richer in histidine than the white muscle. (iii) Volatile bases like ammonia, trimethyl amines, particularly in marine fishes. (iv) Creatine, taurine, betaine, histamine, glycine, uric acid, carnosine, anserine, etc. (v) Nucleic acid.
Water
Water as a body component of fish plays a major part in the changes occurring during processing and storage with preservation technique. Whatsoever, water is directly involved in the biochemical reactions and diffusion process of the fish body. The water content varies in their limited range in different species of fish. Thus in hilsa, it is very low (53.7%), while in Cyprinus carpio, it is 88.8% and in Tinca tinca 90.2% (Shafi, 2003).
The amount of water in fish body is higher than the birds and mammals. The importance of water is understandable for the fact that an animal body may lose partially all of its fat content and half of its protein and live alive, but a loss of only 10% of its water content causes death. Water is inversely proportional to lipid content as per finding by K.A. Jafri and D. Khawaja (1968). Therefore, any change in the lipid content of body will ultimately reflect the body moisture.
Fats
Like water fraction lipid content also shows marked variations in different months of the year. Fat content of a fish flesh is an important factor that determines the quality of the fish and, therefore, its marketing value. The variation in fat content is usually related to species differences, diet of the fish, season of their collection and age of the fish. The lipid fraction in fresh water teleosts is generally higher in winter months, being maximum in November-December. Thereafter it decreases slowly, reaching minimum in June and July.
The existence of wide disparity in the fatness of fishes in different months of the year is a matter of great economic concern as this indirectly affects the marketing value of the fish. The lipid content in different species varies within wide limits. Thus Hilsa ilisha possesses 19.4%, Silonia silondia 12.1%, and Pangassius pangassius 10.8% representing maximum extents of lipid content. On the other hand, some fishes like Rhinoptera sewelli has 0.50% of lipid contents, Sillago sinama 0.60% and Cirrhina mrigala 0.8% have minimum lipid content low fat content was found in Labeo rohita during breeding season (June July). Similar trend of rise and fall in the lipid content was observed in Singhi (Heteropneustes fossilis).
All indications are directed to conclude that fattening in most fishes occurs daring gonadal regression and after the sexual activities have been completed. Thus fattening seems to be closely associated with gonadal cycle. Slight increase in lipid content in freshwater teleosts during March-April may be due to active feeding. During this period, the water temperature rises so that the fish gets metabolically active. Some relationship between fat content and water ten perature has been reported by some research workers and also some correlation with gonadal cycle and fat content has been observed in some fishes.
Minerals
Fish flesh contains 1 to 2% minerals, the bulk of which is concentrated in fish bones. Minerals in the form of boron, flourine, bromine, lithium and strontium are present in lower concentration in the freshwater fishes than in marine. It has been found that mercury also is present in body, being ina greater concentration than in water. The principal minerals present in body are calcium magnesium, potassium, sodium, phosphorus, iron, silicon, chlorine, copper, manganese, iodine, bromine, etc. Traces of strontium, zinc, barium, aluminium, lead, cobalt, nickel, mercury, cadmium are also present.
It has been found that phosphorus is also present in adequate quantity in the form of phosphoproteins, phospholipids, complex phoric acids such as vitamin B1 and B12, glycerophosphatides and adenosinopolyphosphates.
Different information on nutritional composition of freshwater fishes of Bangladesh is necessary in formulating management and conservation policies as well as in the further development of the Fisheries technology and Nutrition.
The present study conducted based on review on nutritional composition of fresh water fishes of Bangladesh. Review means a second or repeated view of something. It can also be defined as a viewing of the past contemplation or consideration of past events, circumstances or facts. In this present study has tried to review by using secondary data that means the data which are collected directly from books, Journals etc written by the different authors.
Different aspects of biological review work of fresh water fishes of Bangladesh have been done by different authors but little work has been done on the nutritional composition of the fishes.
Therefore, the following objectives are set up for conducting a good research-
· To know the nutritional composition of freshwater fishes of Bangladesh.
· To know the variation of nutritional composition from species to species or group to group variation with age, size, habitate and seasonality.
· To know the variation of nutritional composition between after and before of fish processing.
· To quality control of fish during fish processing in industry.
The present study is important for the following reasons-
· It helps to know the nutritional value of different fresh water fishes of Bangladesh.
· From the research it will be easy to know the fish or fish group which contain the higher level of protein, moisture, fat, carbohydrate, energy, ash, Ca (Calcium), P(Phosphorus), F(Iron) etc. and which contain lower level.
· The present review work will helpful for to distinguish fishes from species to species or from group to group depending on the protein level (main parameter to measure nutritionally valuable fish) which is very important from fish culture aspect.
ABSTRACT
The study was conducted on the review on nutritional composition of freshwater fishes of Bangladesh. Data from secondary source (Book, Journal, thesis) was collected for study and analysis of nutritional composition was done from January, 2011 to June, 2011.
The Nutrient content varied greatly species to species. It also varies from group to group from order to order. However, there was inverse relationship between the protein content and moisture content. The result indicated that the maximum and minimum protein contents of different freshwater fishes of Bangladesh were recorded 21.80% (in Hilsha ilisha) and 14.08% (in Puntius chola) respectively. Maximum fishes contained average 17.29% protein level. On the other hand the higher and lower moisture content were recorded 83.5% (in Chaca chaca) and 53.70% (in Hilsa ilisha) orderly. The result indicated that the maximum fresh water fishes of Bangladesh contain average 5.16% lipid level. The result also showed that maximum carbohydrate were found 3.72(average)%. In this study, it was found that the higher energy contents 273Kcal/100mg (in Hilsha ilisha) and lower 14 Kcal/100mg (in Ompok Pabda). The investigation indicated that the average ash and mineral contents of fresh water fishes of Bangladesh was 4.19% and 1.56% respectively. In this study it was found that small fish, which are less than 10cm in length contain large amounts of Calcium (Ca), Iron (Fe) and Phosphorus (P).
In the present investigation it was found that maximum protein containing fish group is Shads and Herrings and minimum in Minnows and barbs. The higher and lower moisture containing fish group was cat fishes and Shads and Herrings orderly. The higher value of mineral were in Feather backs and Snake heads and the lower value were in Indian major carp. The maximum and minimum energy content in Shads and Herrings and Catfishes accordingly. The higher and lower value of Ca were in Snake heads and Minnows and barbs respectively. The maximum and minimum value of P were in Snake head and Minnows and barbs orderly. The higher value of Fe were in Minnows and barbs and lower in Climbing parches and Goramies. The maximum Vitamin contents were in Feather backs and Shads and Herrings and Minimum were in Climbing parches and Groamies. The nutritional composition varies greatly between farmed and wild fish due to habitat changes. The study indicated that the farmed fish species is nutritionally better than wild species.
CONTENTS
Acknowledgement
Contents
Abstract
CHAPTER-1: Introduction
CHAPTER-2: Materials and Methods
CHAPTER-3: Results and Discussion
CHAPTER-4: Conclusion and Recommendation
CHAPTER-5: References
APPENDICES
Review, Nutritional, Composition, Freshwater, Fishes, Bangladesh, Puntius, Chola, Padma, Jamuna, Meghna, Ponds, Beel, Haor, Baor, Freshwater, Fishes, Food, Catla, Labeo, Rohita, Cirrhinus, Mrigala, Silver, Grass, Common, Carp, Hilsa, Ilisha, Gadusia, Chapra, Septipinna, Phasa, Tilapia, Biochemical, Composition, Fish
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