Fortifying Depurated Clams: Evaluation of the Antioxidant and Nutritional Impact of Microencapsulated Diets Containing Nannochloropsis sp. and Vitamin Supplementation

Abstract

Conventional bivalve depuration protocols may compromise organoleptic and nutritional quality, largely as a consequence of fasting. This study investigates an innovative post-depuration feeding strategy in the clam Ruditapes decussatus using microencapsulated diets containing Nannochloropsis sp. supplemented with either a standard dose of vitamins C and E (MV) or a high dose—4× the standard level—of these vitamins (MV+). A three-phase experiment was conducted comprising 24 h of depuration, 2 h of post-depuration feeding, and 6 days of refrigerated storage at 5 ± 1 °C. Clams were sampled after feeding (PF) and after refrigerated storage (PS) and assessed for condition index (CI), vitamin C and E contents, antioxidant defense markers, including catalase activity (CAT) and total glutathione (tGSH), and oxidative damage, assessed through lipid peroxidation (LPO). CI did not differ significantly among dietary treatments. At PF, dietary treatment modulated antioxidant-related responses, particularly in the MV+ group. In the digestive gland, MV+ showed significantly lower LPO than the Control at PF, whereas after refrigerated storage this response was reversed. These findings indicate that the potential benefits associated with vitamin-enriched post-depuration feeding were not fully retained, with increased LPO at PS indicating greater oxidative damage. Further research is required to optimize this feeding strategy and evaluate its feasibility at commercial scale.

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