Spray-Dried Encapsulation and Antioxidant Activity Retention of Sardine Protein Hydrolysate: Structural and Physicochemical Characterization

Marine protein hydrolysates are valuable sources of antioxidant bioactive peptides but are susceptible to degradation during processing and storage. Encapsulation can improve their stability and facilitate their incorporation into food matrices. This study evaluated the encapsulation and antioxidant activity retention of a sardine protein hydrolysate (SPH) from Opisthonema bulleri, O. libertate, and O. medirastre. The SPH contained 61.88 ± 0.84 g kg−1 crude protein, with 71.58 ± 1.54% of peptides ranging from 1.35 to 17 kDa. SPH was encapsulated by spray drying using maltodextrin and gum arabic under three processing conditions. FTIR revealed spectral changes after encapsulation, while AFM showed differences in nanoscale surface features. Processing conditions significantly affected production yield, surface feature size, and antioxidant activity retention. ESPH1 (150 °C inlet temperature, 60 °C outlet temperature, and 9.4 mL min−1 feed flow rate) showed the highest production yield (69.13 ± 0.72%), smallest surface features (141 ± 32 nm), and antioxidant activity retention of 67.41% for ABTS, 70.76% for DPPH, and 99.85% for FRAP. These findings support spray-dried SPH as a potential powdered antioxidant functional ingredient for incorporation into food formulations.