Fatty Acid Analysis and Quality Indices Assessment of Edible Puffer Fish Oils from Sarawak and Sabah

Nur Eqmal Dinie, Nor Azmi (2024) Fatty Acid Analysis and Quality Indices Assessment of Edible Puffer Fish Oils from Sarawak and Sabah. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Puffer fish is traditionally considered by-catch in Malaysia, have gained popularity in Sabah and Sarawak markets as a delicacy. However, there remains a notable gap in the understanding of their fatty acid composition and potential health benefits associated with consumption. Therefore, this study aims to investigate the fatty acid composition of puffer fish species particularly those popular in the markets of Sabah and Sarawak to enhance understanding of their nutritional profile and potential health benefits for consumers. The extraction of puffer fish oil from both liver and muscle tissue involved the utilization of solvent (Bligh and Dyer method) and non-solvent (cooking-pressing by boiling and steaming) methods. The fatty acid composition of puffer fish oils was analysed using Gas Chromatography-Mass Spectrometry (GC-MS) after the Fatty Acid Methyl Ester (FAME) process. Quality indices such as Free Fatty Acid (FFA), Acid Value (AV), Peroxide Value (PV), Saponification Value (SV), and Iodine Value (IV) were assessed according to American Oil Chemists’ Society (AOCS) standards. The Index of Thrombogenicity (IT) and Index of Atherogenicity (IA) were determined to explore potential health effects. Antibacterial and antioxidant activity of puffer fish oil were investigated using MIC and scavenging activity assays, respectively. Solvent method showed the most outstanding fish oil yield result where it yields the highest throughout all species in both liver (average: 36.85%) and muscle (average: 3.57%) samples as compared to non-solvent method (liver: 22.09%, muscle: 0.88%). Non-solvent method demonstrated a satisfying oil yield percentage from liver sample which are 24.20% and 19.97% from boiling and steaming, respectively. Among the species, Lactoria cornuta showed the highest fish oil yield average of 24.4%. The fatty acid composition exhibited a trend, with puffer fish oil extracted via the solvent method showing higher levels (liver: 31.54-39.23%, muscle: 23.96-32.27%) of polyunsaturated fatty acids (PUFA). Conversely, the heating process employed in non-solvent methods reduced the proportion of unsaturated fatty acids while elevating the levels of saturated fatty acids (SFA), mainly from the palmitic and stearic acid. The solvent method consistently produced oils with lower FFA (liver: 1.46-6.11%, muscle: 1.27-6.33%) compared to non-solvent methods through cooking-pressing by boiling technique (liver: 1.60-8.04%, muscle: 1.55-2.96%). The non-solvent method through indirect heating of steaming technique showed a higher quality indices of puffer fish oil as compared to direct heating through boiling technique. However, PV and IV varied across extraction methods and fish species. Fish oils extracted via solvent exhibited lower ratios (liver: 0.63-1.18, muscle: 0.73-0.96) of Omega-6 to Omega-3 (w-6/w-3). Generally, puffer fish oils extracted via solvent method exhibited lower MIC values against both Gram-positive and Gram-negative bacteria compared to those obtained through non-solvent methods. The cooking-pressing (steaming) method showed MIC values that are similar to those of the solvent method. Puffer fish oils extracted using solvent exhibited higher inhibition percentages compared to those obtained through non-solvent methods. This study highlighted the efficiency of non-solvent extraction methods, which offer comparable fish oil yields and quality to solvent extraction. Certain puffer fish species also showed significant attributes for specific parameters.

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