Protein hydrolysate of black seed (Nigella sativa L.) incorporated furcellaran-based double-layer emulsion coating extends shelf-life of carp fish products

The study investigated innovative biopolymer coatings using furcellaran (FUR) and blackseed byproduct protein hydrolysate (BBPH) stabilized emulsion or protein dispersion alone to enhance the quality of refrigerated carp fish. Initially, the effect of the use of different enzymes preparations on the antioxidant activity and functional properties of hydrolysates were investigated. Hydrolysates from Neutrease and Protemax enzymes, with high protein content (72.54 % and 89.51%)89.51 %) and strong antioxidant properties DPPH (75.11 % and 69.74 %), were selected for further study like emulsifying properties and coating development. Both hydrolysates exhibited high solubility (100 %) and high zeta potential (-66.63 and −68.09) at pH 12, with Neutrease showing the smallest droplet size (3.41 ± 0.68μm). The analyzed coatings rheological properties show that their apparent viscosity exhibits shear-thinning characteristics, indicating they are non-Newtonian fluids. This study evaluated the impact of innovative coatings on the quality of carp fish fillets stored for 12 days at 4°C. The color of the carp fish treated with both coatings became darker with a tendency towards reddish and yellowish hues, effectively inhibiting lipid oxidation in fillets over 12 days at 4°C. Therefore, the innovative FUR/BBPH coatings promise to extend the shelf-life of perishable foods. • Neutrease and Protemax enzymes effective in degrading black seed byproduct, have high protein content and antioxidant activity. • Both protein hydrolysates showed the highest stability and solublity at pH12 value. • Two types of innovative coatings were used for fresh carp fish during storage at 4°C. • Coatings darken the color of stored carp fillets due to their high total phenolic content. • Coatings with BBPH have been used to enhance the quality of carp fish.