Introduction

Catfish (Claria geriepinus) is an extensive freshwater fish, found virtually all over the world. It is a lean and highly nutritious fish that is rich in Vitamins, protein, and minerals, and has little or no saturated fat and is low in carbohydrate.¹ Catfish is sometimes eaten raw, but it is usually treated by various processes such as boiling, grilling, baking, frying smoking and oven drying before consumption. Heating (boiling, grilling, baking, and frying) is applied to food to enhance its flavour, tastes and to inactivate some pathogenic microorganism and increase its shelf life.² On the other hand, the use of microwave oven for drying has increased greatly during recent decades.³

Omega 3 and 6 fatty acids are polyunsaturated fatty acids (PUFA), meaning they contain more than one is double bond. Although humans and other mammals can synthesis saturated fatty acids and some mono-saturated fatty acid from carbon groups in carbohydrates and protein. It has been estimated that the ration of omega-6 to omega-3 fatty acid in the diet of early human was 1:1⁴ but the ration in the typical western diet is now almost 10:1 due to increased use of vegetable oils rich in linolenic acid as well reduced fish consumption.⁵

Different cooking methods on proximate and mineral composition of catfish have been studied (6). Drying is one of the oldest methods of preservative components of cell membranes. When incorporated into phospholipids, they affect cell membrane properties such as fluidity, flexibility, permeability and the activity of membrane bound enzymes. It plays important roles in vision and nervous system function. Drying of fish could extend the keeping quality thereby increasing the availability of fish year round, concerns have been raised about the appearance, texture, flavour, and importantly loss of some essential nutritional compositions. Therefore, this study seeks to determine the amount of saturated fatty acids and omega-3 & 6 fatty acids potential in smoked & boiled catfishes.

Materials and Methods

Two freshly harvested catfish (Clariageriepinus) were obtained from a nearby fish farm. The mean weight and length of the fish were 250-300g and 25-30cm respectively. The fish samples were washed with clean water to remove dirt, and were shared into two parts. One part was boiled in water and the other halve was smoked. The samples were dehydrated and blended separately using a kitchen blender; they were kept in labelled airtight containers andwere analyzed in the laboratory. The crude fat analysis was obtained by following the ether extraction method and fatty acids were analysed using gas chromatogram (7).

RESULTS

The result in table 1 indicates the amount of saturated fatty acid in boiled and smoked catfish. Findings show that palmitic and Arachidic where significantly higher in boiled catfish which covered 1.92845^e-5 and 7.44878^e-7 amount/ Area when compared to smoked catfish which covered 1.92734^e-5 and respectively.

Table 1: Gas chromatogram results of saturated fatty acids in boiled and smoked catfish.

The result in table 2 shows the amount of unsaturated fatty acid in boiled and smoke catfish. The study shows that linoleic, Alpha-linolenic and Arachidonre where significantly higher in boiled catfish which covered 9.03517^e-7, 9.56501^e-5 and 1.73060^e-4 amount/area when compared to smoked catfish which covered 6.41263^e-4, 5.45144^e-5 and 1.59797^e-4 respectively.

FATTY ACID CHROMATOGRAM FOR THE PROCESSED CATFISH 

Fatty acid chromatogram of the extracted fat content from boiled and smoked catfish are show in table 1 and 2. With reference to table 1 and 2 the fatty acids of the extracted fat content of clariasgariepinus are generally composed of saturated fatty acid and unsaturated fatty acid. Gas chromatogram illustrate that the boiled and smoked catfish samples have the common fatty acids such as oleic, arachidonic, eicosapentaenoic acid, stearic and docosahexaenoic acid.

Table2: chromatogram results of unsaturated fatty acid in boiled and smoked catfish.Click here to View table

DISCUSSION

Although the result of this analysis work shows that alph-linoleic (Ω-3) and linolenic (Ω-6) of unsaturated fatty acid in boiled catfish is higher than that of smoked catfish. It was observed that about three quarter of the body weight of the catfish consist of water and therefore, an urgent step must be taken for its protection against destructive agent like microorganisms. In this study, more fat content were rapidly removed in the fish when subjected to smoking than boiling. This observation is in agreement with the finding of Andrew, (2001) (8)that boiled catfish generally achieved the required moisture content in food earlier and more uniformly than smoked catfish.

Although unsaturated fats can replace saturated fat in the diet and Trans unsaturated fat should be avoided. Replacing saturated fats with unsaturated fats helps to lower the levels of total cholesterol and low density lipoprotein (LDL) cholesterol in the blood. Foods containing unsaturated fats include avocado, nuts and vegetable oils and unsaturated fats are conventionally regarded as healthier than saturated fats. Omega-3 are found in fish and fish oils and their health benefits are being more fully explored.

Finally the result obtained in this study showed that there were significant influences of the two processed sample on the saturated and unsaturated fatty acid of catfish. Boiling could provide a relative nutritional stability of fish but report of microbial/pest invasion and health implications are serious drawbacks to its uses. The study provides possible application of smoking as an efficient drying process for fish, although its continued use in poor-resource communities in the developing countries is also limited. Thus, the knowledge obtained will improve the capacity of boiled and smoked catfish to its processing methods for fish.

ACKNOWLEDGEMENTS

The authors are grateful to the head of department of Nutrition and dietetics of Rufus Giwa polytechnic, Owo, OndoState, Nigeria.

REFERENCES

1. Ersoy and Yilmaz, (2003). Study the Highly Nutrition Fish that is Rich in Vitamin Protein and Minerals. Journal of Nutrition pp 512-520.
2. Bognor, (1998). Heating is Applied to Fish to enhance it Taste and flavour. Influence  of temperature during storage, Journal of food science and Technology pp. 3314-3320
3. Muniz, et al., (2003). The Use of Microwave Oven for drying in research Decades  (Institution in London) Journal of American Oil Fishes pp. 121-127.
4. Sala vila and Calder, (2011). Omega-6 to -3 Fatty Acid in the Diet has a ratio of 1:1  (Institute in London) Amj. Clin Nutr. 2011: 75:1121. Letter
5. Hilton, et al., (2006). Effect of Omega-3 fatty acids on cancer risk. Journal of the American Oil Chemist Society. Pp. 133-138
6. Yamar and Celik et al., (2006). Study the Different Cooking Methods on Proximateand Mineral Composition of Catfish Food Chemistry pp. 214-216
7. AOAC, Official methods of analysis. Association of official analytical chemicals 15^th Edn USA. 1990.
8. Andrew, A., (2001). Fish Processing Technology, University of Ilorin Press, NigeriaAdvances in Experimental Medicine and Biology pp. 27-43.