Impact of divalent salts and bovine gelatin on gel properties of phosphorylated gelatin from the skin of unicorn leatherjacket

The impact of zinc chloride (ZnCl₂) and calcium chloride (CaCl₂) as well as bovine gelatin (BG) on the gel strength of phosphorylated fish gelatin (PFG) from the skin of unicorn leatherjacket was investigated. The gel strength of PFG increased with increasing concentrations of ZnCl₂ and CaCl₂ (2.5–40 μmol L⁻¹). A higher gel strength was observed with CaCl₂, compared with ZnCl₂. The gel strength of PFG with 20 μmol L⁻¹ CaCl₂ increased by 15.7%, compared to the control gel. Nevertheless, at higher concentration (40 μmol L⁻¹) of both salts, gel strength of PFG decreased. Hardness of gels decreased with increasing PFG content (P < 0.05). Nevertheless, no differences in hardness were found amongst gels with BG/PFG ratios of 4:0 and 3:1 (P ≥ 0.05). Thus, PFG could be used in combination with CaCl₂ to substitute for BG at a level of 25%.