Nutritional attributes in the fillet of skipjack tuna (Katsuwonus pelamis) from the Arabian Sea near the south-west coast of India

Abstract

Inter-annual and seasonal variability in the nutritional parameters of the edible portion of skipjack tuna (Katsuwonus pelamis) collected from the Arabian Sea were determined for a period of 4 years. Greater levels of long chain n-3 fatty acids (35% during pre-monsoon), critical in the human diet for their anti-inflammatory properties with greater n-3:n-6 fatty acid ratio (8:12) demonstrated that this species may serve as an alternative to balance the greater amount of n-6 fatty acids. The present study demonstrated skipjack tuna as a significant source of protein, amino acids, minerals and vitamins. A balanced essential to non-essential amino acid ratio (1.2:1.4) in the fillets indicated that this species could provide well-balanced protein depositions. Vitamins A and K1 demonstrated post-monsoon maxima, whilst vitamins D3 and E showed pre-monsoon maxima. Greater calcium (172 mg 100 g−1) and phosphorus contents (923 mg 100 g−1) were recorded in the fillets of skipjack tuna during the pre-monsoon season. The chlorophyll-a concentration and sea surface temperature of its habitat were considered to understand their effect on the nutritional composition of skipjack tuna all through the study period. Significant correlation between long chain n-3 polyunsaturated fatty acids such as eicosapentaenoic acid and docosahexaenoic acid (r2 ~ 0.99) of skipjack tuna alongside chlorophyll-a concentration was observed, particularly during the monsoon. The lesser atherogenic/thrombogenicity indices (<1), greater hypocholesterolaemic/hypercholesterolaemic ratio (>1.0), and lesser cholesterol contents (<50 mg 100 g−1) of the fillets in skipjack tuna contributed towards its parameters to be qualified as a high value, balanced nutritional source.