Fatty Acid Profiles and Lipid Oxidation Status of Sun Dried, Deep Fried, and Smoked Sardine (Rastrineobola argentea) from Lake Victoria, Tanzania

ABSTRACT

Freshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constituting 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 µmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.

KEYWORDS:

• Dagaa
• omega-3 fatty acids
• freshwater fish
• fish lipids
• thiobarbituric acid reactive substances
• lake Victoria
• sardines
• polyunsaturated fatty acids

Acknowledgments

The authors acknowledge for the financial support provided by the DANIDA supported project “Innovations and Markets for Lake Victoria Fisheries (IMLAF) DFC 14–P01–TAN)”. National Food Institute, The Technical University of Denmark is acknowledged for granting permission and technical support during laboratory work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Danida Fellowship Centre [DFC 14–P01–TAN].