Nutritive Value of Fresh and Smoked Fish (Clarias gariepinus and Oreochromis niloticus) from Dadin Kowa Dam Gombe

Greener Journal of Biological Sciences

Vol. 11(2), pp. 54-64, 2021

ISSN: 2276-7762

http://gjournals.org/GJBS

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Nutritive Value of Fresh and Smoked Fish (Clarias gariepinus and Oreochromis niloticus) from Dadin Kowa Dam Gombe

¹Umar, D. M.; ²Saje, W. S.; ³Abbati, M. A.

^1&2Department of Biological Sciences, Gombe State University, Gombe, Nigeria.

³Department of Biological Sciences, Federal University of Kashere, Gombe, Nigeria.

ARTICLE INFO

ABSTRACT

Article No.: 081821079

Type: Research

Two fish species; Clarias gariepinus and Oreochromis niloticus weighing 2kg each were used for this study in order to determine the nutritive value of the fish species. Each fish species was divided into two batches, the first batch of catfish and tilapia were killed, gutted, washed, salted and smoked, while the second batch was used immediately for proximate analysis. Analysis of moisture, protein, lipid, ash and fibre were carried out for fresh and smoked samples using oven, kjeldahl, muffle and furnace. The mean range of fresh fish samples moisture was 81.00% and 81.33% in Clarias gariepinus and Oreochromis niloticus. Protein was 21.67% and 25.43% in C. gaiepinus and O. niloticus. Lipid content was 12.5% and 3.5% in C. gariepinus and O. niloticus. Ash was 0.09% and 0.25% in C. gaiepinus and O. niloticus Fibre content was 0.18 and 0.24% in C. gaiepinus and O. niloticus respectively. In smoked fish samples, composition of moisture was 28.33% and 30.67% in C. gariepinus and O. niloticus. Protein is 28.75% and 26.10% in C. gaiepinus and O. niloticus. Lipid resulted to 1.0% and 2.1% in C. gaiepinus and O. niloticus. Ash content is 0.13% and 0.30% in C. gariepinus and O. niloticus and fibre content resulted to 0.19% and 0.33% in C. gariepinus and O. niloticus respectively. The results reveals that smoking has positive effect on the fish species examined in this study. High amount of protein, fibre and ash were recorded in smoked samples at (p<0.05) level of significance with low moisture and lipid content, while high moisture and lipid was recorded in fresh fish samples.

Accepted: 19/08/2021

Published: 31/08/2021

*Corresponding Author

Abbati MA

E-mail: muhabbaty0708@ gmail.com

Keywords: Nutritive value; Fish; Dadin Kowa; Reservoir.

INTRODUCTION

Fish is important for food security and poverty alleviation in both rural and urban areas in Nigeria. Only little is known about the nutritional value of the fishes that are being utilized either as fresh or preserved. The principal components of fish include water, protein and fat. While the minor components include carbohydrates, minerals vitamins and extractives such as free amino acid and nitrogenous bases (FAO, 2014).

African catfish is a freshwater fish having variety of body shapes, with no scale some have cylindrical body with a flattened ventrum for benthic feeding and some use their skin for cutaneous respiration (Nelson, 2006). Tilapia inhabits fresh water and it is found in shallow streams, ponds, rivers and lakes and cannot survive in temperate climate. They are fast growing, lean and short lived with primarily vegetarian diets which contain low level of mercury (Mc crary et al., 2005). It is low in saturated fats, calories, carbohydrates, sodium, potassium, phosphorous, niacin and is a good protein source. Catfish and tilapia are in a very high demand in the middle belt and northeast of Nigeria on account of their tasty flesh (Aremu et al., 2008). The species are very popular with farmers and consumers, Catfish also command a very high commercial value in Nigerian markets (Diyaware et al., 2007).

Fish is a nutrients rich food and a very good source of vitamins and minerals required by humans (Ojutiku et al., 2009). Studies further shows that pond raised fish exhibit deviants flesh quality characteristics and nutrient content than wild fish (Makwinja et al., 2013).

Fish processing is a set of procedures used to keep fish away from deterioration or decay. It is a process associated with fish and fish products between the times in which the fish final product is delivered to the consumer. The processing and preservation of fish are highly susceptible to deterioration immediately after harvest (Okonta et al., 2005). However, fish is an extremely perishable commodity, spoiling soon after death due to enzymatic and microbial action. Some factors responsible for this action includes prevailing high temperature in Nigeria and poor facilities for processing, storing and distributing of the fish caught. Frequently, inadequate or non-essential in most cases, there is enormous waste through spoilage of fresh fish (Oluwaniyi et al., 2010).

A number of processing techniques are in operation in Nigeria, these techniques includes; freezing, canning (Modern method of preservation) and sun drying, smoking (traditional method of preservation). However, smoking is the most popular method of fish processing (Eyo, 2000). Therefore, smoking involves heat application to remove water and inhibit bacteria and enzymatic action on fish, its aroma test and color on processed fish.

There are several ways of accessing quality of fish products, whether smoked, sun-dried frozen or canned. These are physical examination, microbiological, entomological and sensory method. In Nigeria, Ghana and other West African countries a number of processing technique such as smoking, freezing, salting and sun drying are employed by fish processors (Adeyemi et al., 2013). Smoked fish is considered as delicacy in Alaska and Pacific Northwest (cooperative extension service, 2012).

Rahji and Bada (2010) reported that while Nigeria requires about 1.5 million tons of fish annually and it is expected to meet Food and Agricultural Organization (FAO) recommendation minimum fish consumption rate of 12.5 kilograms per head yearly to satisfy protein needs, the fish supply and demand gap.

According to Davies et al., (2008) the processed fishery products were still stored using traditional processing and storage technologies, especially lack of adequate fish handling processing techniques and storage facilities contribute significantly to the low fish supply to poor rural dwellers that form 3 quarters of the population in developing country (Ayuba et al., 2006).

The aim of this research is to determine the nutritional values of Clarias gariepinus and Oreochromis niloticus.

METHODS

Study site

Gombe is a city in north eastern Nigeria State Capital and a Local Government Area. It is located between latitude 10° 17N and 11°10E and longitude 10.283°N and 11.167°E. The LGA has a total area of 52km². It is the capital city of Gombe State and has an estimated population of 268,000 (Population Census, 2006). The city is the headquarters of the Gombe Emirate, a traditional state that covers most of Gombe State (Gombe State Online Nigeria Daily, 2010).

Extraction of the samples was carried out in biology laboratory, smoking was carried out in biological garden and proximate analysis was conducted in biochemistry laboratory, Gombe State University.

Sample collection

Fresh fish samples of Tilapia (Oreochromis niloticus) weighing 2kg and catfish (Clarias gariepinus) weighing 2kg was purchased from fishermen in Dadin Kowa dam, Gombe State, Nigeria. The fresh samples were transported to the biology laboratory and divided into two batches, the first batch was prepared for smoking, while the second batch was sacrificed immediately for proximate analysis.

Killing

Killing was done by hitting the head of the fish with a heavy or sharp object several times or dipping the fish in a concentrated salt solution (only for fresh water fishes).

Degutting

Fish samples were dissected and the stomach contents removed (guts i.e. intestine, eggs).

Washing

Fish samples were washed thoroughly with a clean water to remove blood stains, after which it was hanged to drain water from the fish.

Salting

Salt granules was rubbed all over the surface of the fish samples (dry salting).

Smoking

The fish samples were laid on the racks of smoking kiln. Heat and smoke was generated by burning of charcoal from log of wood (Acacia SPP) and smoking of the samples was be carried out. The temperature was maintained above 30^oC and the normal range is 70-80^oC smoke produced by burning of sawdust or log of wood (different species) as practiced by local fish mongers (Salan et al., 2006). After smoking, the products were packed into a polythene bag to reduce pest/microbial infestation (Abolagba et al., 2008), it was kept in the refrigerator (Haier thermocool) at 1-5^oC for two days.

Proximate Analysis

Fresh and smoked samples for proximate analysis were prepared, each of the two fish species was analyzed following a procedure by Association of Analytical Chemist (AOAC, 2005).

Protein Determination

Protein content was determined using micro Kjeldahl method. 3g sample from each of the two species of fishes was digested in a kjeldahl flask using 25ml H₂SO_4
,5.0g Na₂SO₄and 0.5g CuSO_4.The digest was then distilled in an upper layer of soxhlet apparatus in the presence of boric acid, methyl red indicator and 1.25 NaOH. The distillate was then titrated against 0.1ml HCl to get the end point value, Protein content will be determined as nitrogen and multiplied by 6.25 to get the crude protein value.

Lipid Determination

Fat content was determined using 3g sample of fish placed in a flask and 5ml petroleum ether was added and placed on orbital shaker, it was shaken for 3hours and filtered. The filtrate was left to stand for 24hours after which the ether had evaporated to dryness. The amount of fat will be obtained as difference in the weight of the flask before and after drying of the ether. Percentage of lipid was determined by using the following formula:

% lipid =

Crude fibre Determination

Fibre was determined by heating the residue recovered from fat determination with distilled H₂SO₄, then washed with hot distilled water. It was then heated with diluted NaOH and washed, the residue was dried in an oven and reweighed. After weighing it was placed in a muffle furnace and ashed at 600⁰c, the crucible and ash sample will be reweighed. Calculations were done by using the formula:

% crude fibre =

Moisture Determination

Moisture content was determined using 3g sample of fish placed in a crucible and dried at 105^oC to a constant weight after the initial weighting. Moisture content of the fish was then calculated by subtracting the final from the initial weight of the fish sample. The percentage moisture was calculated by the following formula.

% moisture =

Where, W1 = initial weight of crucible + sample

W2 = final of crucible + sample

Ash Determination

Ash content will be determined by using 3g sample of ground fish was placed in a crucible then ashed at 600^oC for 6 hours in carbolite muffle furnace then cooled to room temperature. The amount of ash is given by the difference in weight of the crucible before and after drying. Percent was calculated by the following formula:

% ash =

Difference in weight of ash = W₃ – W₁

RESULTS

Moisture Content

Moisture content for fresh and smoked samples of Clarias gariepinus and Oreochromis niloticus is shown in figure 3. Percentage moisture content of fresh catfish sample was 81.00% and that of smoked catfish is 28.33%.Moisture content of fresh tilapia was 81.33% and that of smoked tilapia is 30.67% In contrast to protein, crude fibre and ash, the moisture of fresh catfish samples decreased sharply after the smoking process.

DISCUSSION

Moisture content of a given sample simply refers to the water content of that sample. Result of moisture content in fresh samples of Clarias gariepinus and Oreochromis niloticus were 81.00% and 81.33%, after the smoking process the moisture content decreased to 28.33% and 30.67% respectively. The improved shelf life of fish may be due to action of smoke and heat that reduces water activity and impaired the action of spoilage microbes (Abolagba and Osifo, 2004). It has been observed that fish well dried with moisture reduced to 28% will not be affected by spoilage organisms like mould and that if further dried to moisture content of 15% the growth of mould will cease and shelf life will be increased (Oparaku and Mgbenka, 2012).

The observed reduction in moisture content on smoked sample was due to loss of moisture during smoking as observed by (Salan et al., 2006). This was based on the report of (Kumolu and Ndimele, 2001) which assessed that spoilage of fish resulting from the action of enzymes and bacteria can be slowed down during smoking.

Protein content determined in the fish species are 21.67%, 25.43% and 28.75%, 26.10% in fresh and smoked samples of Clarias gariepinus and Oreochromis niloticus respectively. The crude protein content of the smoked samples was found to be 28.75% and 26.10%, this value is lower than the value of 53.10% recorded by Ogbonna and Ibrahim (2009).

It is observed that protein content increase with decrease in moisture content (Aliya et al., 2012). The high tissue protein content of the fish species in this study may be related to high protein content of their common diets as they fed mostly on crustaceans, mollusks and algae (Osibona et al., 2006). In the fresh samples, higher amount of protein was recorded in Oreochromis niloticus while in smoked samples Clarias gariepinus has higher protein content. Chemical composition of fish varies greatly from one individual to another depending on species, age, sex, environment and season (Bolawa et al., 2011).

The lipid content in fresh Clarias gariepinus and Oreochromis niloticus was 12.5% and 3.5%, after the smoking process the lipid content recorded is 1.0% and 2.1% respectively. The results of lipid disagrees with the work of Omojowo et al., 2008 and da Silva et al., 2008, lipid content was shown to have decreased in their research, but in this study the lipid content has decreased sharply as a result of heat generated during smoking which burns down fat contained in the fish.

Fish species with lipid content below 5% are considered lean Ackman, 1989. Oreochromis niloticus was observe to have low lipid content (less than 5%) in both fresh and smoked samples. Hence, it could be said that Oreochromis niloticus is lean fish species while Clarias gariepinus is a fatty fish according to Ackman (1989) classification. However, it is said that fatty acid composition of fish tissue can be affected by diet, size, age, reproductive cycle, temperature and geographical location (Zenebe, 2010).

Result of ash content in fresh samples of Clarias gariepinus and Oreochromis niloticus were 0.09% and 0.25% and in smoked samples ash content resulted to 0.13% and 0.30% respectively.

Result generally showed an increase in ash content of smoked Clarias gariepinus and Oreochromis niloticus which are in agreement with earlier studies of (Oparaku and Mgbenka, 2012). The increase in ash can be attributed to dry matter content per unit weight following simple dehydration during the smoking process (da Silva, 2002). Results of ash content agree with the work of Omojowo et al., (2008) and da Silva et al., (2008).

Fibre content in fresh samples of Clarias gariepinus and Oreochromis niloticus were 0.18% and 0.24% while in smoked samples of Clarias gariepinus and Oreochromis niloticus fibre resulted to 0.19% and 0.33% respectively. There was no significant difference at (p>0.05) in fibre content of the individual both fresh and smoked samples of the two fish species.

Although slight increase was recorded in the two fish species, the increase in crude fibre can be attributed to dry matter content per unit weight following simple dehydration during the smoking process (da Silva, 2002).

SUMMARY

The study, comparative study on the nutritive value of smoked Clarias gariepinus and Oreochromis niloticus which was conducted at Gombe State University, Gombe state Nigeria. With the view to compare the nutritional composition and evaluate the changes in protein, lipid, fibre and ash of fresh and smoked samples. The overall changes showed that smoking has increased the percentage of protein, fibre and ash while that of lipid and moisture has decreased.

The result of the study revealed that smoking has a positive effect on catfish and tilapia. Of all methods of fish preservation, smoking is the most popular method in the sense that smoking removes water which inhibits bacteria and enzymatic action on fish.

CONCLUSION

In conclusion, the result of this study revealed an increase in protein, fiber and ash when fish is subjected to smoking, lipid and moisture content has shown to have decreased. It also reveals that the smoke generated during smoking changes the color of the fish and gives it pleasant aroma and taste. The finding of this research shows that smoking is of greater advantage than other means of fish preservation as it is affordable and cheap.

RECOMMENDATIONS

Persons watching their body fat should go for Oreochromis niloticus because it is a lean fish with low lipid content. Consumers should go for Clarias gariepinus since it has more protein than Oreochromis niloticus. Smoked fish should be given priority by fish processor, seller and consumer, due to the tendency of deterioration due to putrefaction is minimal.

ACKNOWLEDGEMENT

We wish to thank all those who contributed in this work, right from field to laboratory investigations.

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