Inter-annual variability and seasonal dynamics of amino acid, vitamin and mineral signatures of ribbon fish, Trichiurus lepturus (Linnaeus, 1758)

Trichiurus lepturus (ribbon fish) was collected from different spatial locations (south west (SW) coast edging the Arabian Sea and south east (SE) coast surrounding the Bay of Bengal of India) and seasons (pre-monsoon, monsoon and post-monsoon) during a continuous period of four years (2008 through 2011), and their edible muscles were studied for differential nutritional compositions of protein, amino acids, vitamins and minerals. The MODIS/ AQUA-derived near-surface chlorophyll-a concentration of its habitats were taken into account to understand their effect on the nutrient signatures of ribbon fish throughout the study period and locations. Seasonal mean protein content attained its maximum during monsoon along the SW (23.4 g/100 g) and SE (11.7 g/100 g) coasts, with higher proportions of essential amino acids (60%) recorded in the samples obtained from the SW coast. The essential to non-essential amino acid ratio was found to be more than 1.0 during the three seasons (> 1.2) along the SW coast, and during monsoon along the SE coast. Total aromatic (TArAA) and total sulphated amino acids (TSAA) recorded monsoon maxima along the SE and SW coasts. Amino acid scores observed monsoon and post-monsoon maxima along the SW and SE coasts, respectively. Mineral content in T. lepturus collected from the SE coast was found to be significantly higher during the monsoon season. Significant seasonal variations of vitamin content in T. lepturus were observed along the study locations with higher vitamin A, D3 and C contents at the SW coast and vitamins E and K1 at the SE coast. The present study demonstrated T. lepturus as a valuable source of the well balanced proteins/amino acids with high-biological value, minerals, and vitamins to be qualified as a preferred health food for human diet.