Lipid oxidation levels in different parts of the mackerel, Scomber scombrus

• Published in: Journal of aquatic food product technology Vol. 7; no. 2; pp. 17 - 29
• Main Authors: Icekson, I, Drabkin, V, Aizendorf, S, Gelman, A
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 29.01.1998
• Subjects: animal tissues; estimation; fat; fish quality; lipid peroxidation; lipid-oxidation; Mackerel; malonaldehyde; malondialdehyde; Marine; organic acids and salts; peroxide value; sampling; Scomber scombrus; spatial variation; thiobarbituric acid value; weight
• ISSN: 1049-8850; 1547-0636
• DOI: 10.1300/J030v07n02_03

The estimation of the lipid oxidation levels in fish is frequently done using the thiobarbituric acid method. The usual reporting method refers to the amount of malonaldehyde (MA) found per fresh weight of fish, which introduces a certain bias because MA is derived solely from the fat content of the fish, and the range of fat content in different fish may vary from 0.5 to 30%. The sampling procedure may use several whole small fish, a single fillet in a medium sized fish, or any portion of a larger sized fish. Bias may be introduced, especially when dealing with fish in which only a random sample is utilized, since different parts of the fish contain differing amounts of fat and the rate of lipid oxidation in different anatomical parts is not uniform, Mackerel (weighing 500-600 g) were kept frozen at −18°C and, at different times, samples (n = 4) were taken and the TBA value and fat content were determined in three dorsal (cranial, medial and caudal) and three ventral (cranial, medial and caudal) samples of approximately the same length. The results show clearly that MA content expressed per total weight is similar in the ventral and dorsal sections, however when the MA content is expressed per fat weight, the dorsal sections show an MA content higher than the ventral sections by some 50% in the cranial and medial areas. In the caudal area dorsal and ventral sections do not show a significant difference in MA content, both being higher than the MA content in cranial and medial sections. The fat content of the ventral section was significantly higher than the dorsal section in both the cranial and medial sections. The results show that in mackerel, the lipid oxidation level is not uniform in different sections and the caudal sections have the highest lipid oxidation level. From these results, the proposition arises that a better estimation of the lipid oxidation level would be obtained by expression of the MA content per fat weight, and that the most oxidized part in each fish should be used as the sampling site for the determination of the lipid oxidation level. This should provide a certain safety margin, knowing that the highest possible value in any given sample is being determined.