The preferential use of a soy-rapeseed lecithin blend for the liposomal encapsulation of a tilapia viscera hydrolysate

Viscera of tilapia (Oreochromis spp.) were used for the production of a protein hydrolysate, which was characterized in terms of proximate composition, molecular weight distribution, amino acid composition and antioxidant activity (ABTS radical scavenging capacity, ferric ion reducing power (FRAP) and ion chelating activity). Liposomes from soy lecithin (SL), rapeseed lecithin (RL), and soy-rapeseed (SRL) lecithin blend (1:1, w/w) were prepared, showing average particle sizes of 153, 218 and 193 nm, respectively, and similar zeta potential of -46 mV. Rapeseed lecithin liposomes presented much higher antioxidant activity than with SL. Liposomes made of SRL, having intermediate hydrodynamic and antioxidant properties than the other two, were selected to encapsulate the tilapia hydrolysate at different concentrations (5, 10 and 20 g/100 g, with respect to lecithin). Liposomes loaded with 20 g/100 g of hydrolysate (SRLH20) had smaller particle size and higher ABTS values and iron chelating activity, while liposomes loaded with 5 g/100 g (SRLH5) had higher electronegative zeta potential and entrapment efficiency, which was calculated as a function of total protein content, antioxidant capacity and individual amino acid residues. Charged amino acid residues and alanine were highly entrapped in both SRLH5 and SRLH20. No clear preference for encapsulating hydrophobic or hydrophilic amino acids was observed.

Automated summary

In this study, protein hydrolysate from tilapia viscera was produced and encapsulated in liposomes made from different types of lecithin. Lecithin liposomes prepared with a soy-rapeseed lecithin blend showed intermediate hydrodynamic and antioxidant properties, making them the ideal choice for encapsulating the tilapia hydrolysate. Liposomes loaded with 20 g/100 g of hydrolysate had smaller particle size and higher antioxidant capacity compared to liposomes with lower concentrations. Charged amino acid residues and alanine were found to be highly entrapped in both low and high concentration hydrolysate-loaded liposomes.