-Nutritional composition dynamics of Scylla paramamosain across molting stages

The mud crab Scylla paramamosain , with its distinctive flavor and high nutritional value, holds significant economic importance in the aquaculture industry and as a highly sought-after seafood option. This study examines the nutritional composition of S. paramamosain across molting stages (premolt, ecdysis, postmolt I, and postmolt II) and between sexes. Moisture and ash content were highest during ecdysis and postmolt I. Crude protein levels peaked in the premolt stage (females: 73.88±0.73%; males: 72.42±1.15%), supporting tissue development, while crude fat content was highest in hard-shell crabs, particularly in the postmolt II stage. Mineral analysis revealed elevated calcium, magnesium, iron, and copper in soft-shell crabs (ecdysis and postmolt I), while carotenoid content was highest during ecdysis stage (females: 81.35±8.34 mg/kg; males: 88.45±4.12 mg/kg). Among the 21 identified fatty acids, saturated fatty acids were most abundant during ecdysis, whereas polyunsaturated fatty acids, particularly eicosapentaenoic(females: 13.27±0.83%; males: 13.98 ± 0.19%) and docosahexaenoic acids (females: 10.25±0.25%; males: 10.22 ± 0.43%), increased significantly in postmolt II. Amino acid profiles showed total, essential, and flavor amino acids peaking during premolt, with glycine, glutamic acid, aspartic acid, and arginine being most abundant. These findings provide valuable insights for aquaculture optimization and the commercial enhancement of soft-shell crabs. • Nutritional composition of Scylla paramamosain varies significantly across molting stages. • Moisture, ash, and carotenoid content peak during ecdysis and early postmolt stages. • Calcium, magnesium, and selenium increase significantly during postmolt for shell formation. • Elevated EPA and DHA levels during postmolt II stage offer superior nutritional value. • Crude protein and essential amino acids are highest in the premolt stage, enhancing growth.