Biochemical factors involved in the resistance of some smoked tropical fish samples to insect attack
The role of mineral elements (ppm), protein and oil content (%), and saponification and free fatty acid values in contributing to resistance against insect infestation was investigated in 4 fish species: Clarias gariepinus, Parachuma obscura, Hydrocynus sp., and Malapterus electricus. Smoked fish samples were purchased from a local market in Ilorin, Kwara State, Nigeria, packaged, and maintained at 4 °C for 7 days. They were later brought out to acclimatise, and then observed for 4 months for possible natural insect infestation. Next, crushed samples of each species were analysed using conventional chemical analysis in order to assess the role of some elements and biochemical compounds in inducing resistance. The results showed that insect infestation did not occur after the period of storage (4 months) and chemical analysis showed that 3 samples lacked lead (Pb), a heavy metal not required in trace amounts, but contained other heavy metals required in trace amounts, such as Fe, Mn, Co, and Cu. Protein content in the 4 samples was average (50%), but oil content was low. Hydrocynus sp. and Malapterus electricus had an acid value below 50 mg KOH/g. Additionally, all the samples had high a saponification value (above 500 mL/g). The presence of iron (>=1.5), high protein (%) and saponification values, low oil content, and low acid values of between 35 and 90 were the elements and biochemical constituents that prolonged the shelf life of the fish species studied.
Biochemical factors involved in the resistance of some smoked tropical fish samples to insect attack
The role of mineral elements (ppm), protein and oil content (%), and saponification and free fatty acid values in contributing to resistance against insect infestation was investigated in 4 fish species: Clarias gariepinus, Parachuma obscura, Hydrocynus sp., and Malapterus electricus. Smoked fish samples were purchased from a local market in Ilorin, Kwara State, Nigeria, packaged, and maintained at 4 °C for 7 days. They were later brought out to acclimatise, and then observed for 4 months for possible natural insect infestation. Next, crushed samples of each species were analysed using conventional chemical analysis in order to assess the role of some elements and biochemical compounds in inducing resistance. The results showed that insect infestation did not occur after the period of storage (4 months) and chemical analysis showed that 3 samples lacked lead (Pb), a heavy metal not required in trace amounts, but contained other heavy metals required in trace amounts, such as Fe, Mn, Co, and Cu. Protein content in the 4 samples was average (50%), but oil content was low. Hydrocynus sp. and Malapterus electricus had an acid value below 50 mg KOH/g. Additionally, all the samples had high a saponification value (above 500 mL/g). The presence of iron (>=1.5), high protein (%) and saponification values, low oil content, and low acid values of between 35 and 90 were the elements and biochemical constituents that prolonged the shelf life of the fish species studied.
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- 1. FAO. The prevention of losses in cured fish. Technical paper 219: 87, 1981.
- 2. Oyeleye O. Export potential of smoke fish in Nigeria. The Guardian Newspaper, Lagos, Nigeria 19, 2003.
- 3. Akande GR. Fish processing, packaging and storage: paper presented at training Workshop on green storage and fish processing technology organised by the crop storage unit (CSU) under the programme on post harvest food loss prevention. 1st - 12th September, 222, 1997.
- 4. Eyo A. The significance of fish handling, preservation and processing in the development of Nigeria inland fisheries with special reference to Kanji lake in: processing of the third annual conference of fisheries society of Nigeria (FISSON) Maiduguri, 22nd-25th Feb,(1983), 2003.
- 5. Buckel KA, Sowness RA, Putro S et al. In CC Seow (Ed). Food preservation by moisture control, Elsevier. Applied science publisher LTD, U.K 103 – 115, 1998.
- 6. Akande GR, Tobor JJ. Prospect of fish smoking in the middle belt area of Nigeria. OIMR Technical paper No. 95, 1993.
- 7. Ashamo MO, Ajayi EO. Effect of processing and storage methods on the shelf life and incidence of insect pest on smoked fish. Global journal of pure and appl. Sci 9: 319-324, 2003.
- 8. Khan AH, Ali M, Biaswas SK et al. Trace elements in marine fish from the Bay of Bengal. The Science of the Total Environment 61: 121-130.
- 9. Windom H, Stein D, Sheldo R et al. Comparison of trace metals concentration in muscle of a pentoplagic ( Coryphaeloides armatus) from the Atlantic and pacific Ocean. Deep Sea Research 34: 213-220, 1987.
- 10. Bugress GHO. Increasing the direct consumption of fish in WW Price (ed) food protein sources. International biological programme A. Cambridge University Press, Cambridge. pp 187-200, 1975.
- 11. Kirchgessner M, Schwarz FJ. Mineral content (major and trace elements of carp Cyprinus carpio) fed with different protein and energy supplies. Aquaculture 54: 3-9, 1986.