Emulsion stability and properties of fish gelatin-based films as affected by palm oil and surfactants.

Abstract

Gelatin films exhibit the poor water vapour barrier properties. The use of palm oil, which is abundant and available in Thailand, can be a means to lower water vapour migration. To disperse oil in film-forming dispersion (FFD), a surfactant along with appropriate homogenization is required. The study aimed to investigate the influence of palm oil level and surfactants in the absence or presence of glycerol on characteristics of FFD and resulting gelatin films. Similar oil droplet sizes, both d32 and d43 values, of FFD containing soy lecithin were observed, regardless of palm oil level used (P > 0.05). FFD with Tween-20 had larger droplet size as the levels of oil increased (P < 0.05). After 12 h storage, slight increases in d32 and d43 were noticeable in all FFD samples. When the films were determined, lower water vapour permeability (WVP) and tensile strength (TS) but higher elongation at break (EAB) were obtained as palm oil level increased (P < 0.05), regardless of glycerol and surfactant used. Films without glycerol had lower WVP and EAB with higher TS than those containing 300 g kg(-1) glycerol (P < 0.05). No differences in WVP and mechanical properties were found between films containing both surfactants (P > 0.05). FFD containing 500 or 750 g kg(-1) palm oil using soy lecithin as a surfactant in the presence of 300 g kg(-1) glycerol had the enhanced homogeneity and stability of oil droplets. The resulting gelatin film had the improved water vapour barrier properties. © 2015 Society of Chemical Industry.