Interfacial properties of gelatin from goat skin as influenced by drying methods

Interfacial properties of spray-dried goat skin gelatin (SDGG) and freeze-dried counterpart (FDGG) were determined, in comparison with commercial bovine gelatin (BG). SDGG had the highest surface hydrophobicity (p < 0.05), followed by FDGG and BG, respectively. FDGG became more positively or negatively charged than SDGG at pH below or above pIs (4.83-4.88). Foam expansion and stability of all gelatins increased with increasing concentrations (10-30 g/L) (p < 0.05). SDGG had higher foam expansion and stability than FDGG. Emulsion containing SDGG had the higher droplet size (d₃₂, d₄₃) and flocculation factor than that stabilized by FDGG (p < 0.05). The former also showed the lower stability as indicated by the higher coalescence index with lower negative charge after 10 d of storage. Thus, drying methods affected both foaming and emulsifying properties of goat skin gelatin.