Gelatin films: Study review of barrier properties and implications for future studies employing biopolymer films

Production of conventional packaging materials is now recognised as having had a major impact on world pollution. Edible/Biodegradable/Compostable (EBC) films may offer sustainable alternatives to some conventionally-used packaging materials. One of the largest protein groups available for EBC materials is bovine gelatin. Knowledge and control of gelatin barrier properties is essential if it has any potential of becoming an industrial packaging material. Review of the relevant literature demonstrated that data for gelatin barrier properties generated was generally incomparable owing to a lack of experimental standardisation. Some standard approaches are adopted for further study, particularly, to reach a point where recommendations can be made about industrial use of gelatin as a packaging material. This review investigated barrier properties of bovine-derived gelatin films and factors affecting them for potential future industrial application. Bovine gelatin barrier properties were normalized to the same units and were dependent on film thickness, production methods employed, film composition, relative humidity, plasticizer content and nature, gelatin source and testing methods used. Literature comparison for barrier properties underlined high variability in results. It is suggested, and highly recommended that future studies carried out by researchers investigating EBC films should employ the use of standard units to express water vapor permeability (WVP) and oxygen permeability (OP) values as g x mm (or μm)/m² d atm (or kPa) and cm³ mm (or μm)/m² d atm (or kPa), respectively. Further research is necessary to compare results under controlled test conditions.