Nutritional quality of the carpet shell clam (Ruditapes decussatus): Seasonal variations in proximate composition, amino acid profiles, and vitamin content

This study investigated seasonal variations in the proximate composition, amino acid profile, and vitamin content of the carpet shell clam, Ruditapes decussatus, collected from İzmir Bay, Türkiye. Protein (11.55–12.28%), lipid (1.43–1.88%), and ash (2.34–2.45%) contents did not differ significantly among seasons (p > 0.05), whereas moisture content was significantly higher in winter (79.88%; p < 0.05). Taurine was the predominant amino acid in all seasons, ranging from 489.71 to 692.40 mg/100 g dry weight. The summed concentrations of the reported free amino acids were highest in winter and summer, while the highest sum of essential free amino acids was recorded in summer. Vitamin composition also exhibited marked seasonal variation. Riboflavin, pantothenic acid, thiamine, and nicotinamide reached their highest concentrations in summer at 823.09, 101.05, 25.84, and 22.35 ng/g, respectively. Pyridoxine and vitamin D were highest in autumn, at 1.09 and 20.40 ng/g, respectively, whereas vitamin E was detected only in autumn and winter. These findings indicate that the proximate composition of R. decussatus remained relatively stable, while its amino acid and vitamin profiles varied seasonally. The results provide baseline data for evaluating seasonal changes in the nutritional composition of this commercially important bivalve.