Development of a new family of food packaging bioplastics from cross‐linked gelatin based films

The purpose of this work was to develop green bioplastic preparation process from gelatin by using solvent‐free approach with efficient use of resources. Film plasticizing was achieved by adding polyethylene glycol (Mw = 200 g.mol−1). Different cross linking agents – glutaraldehyde (GTA), N‐hydroxysuccinimide (NHS), Bis(succinimidyl)nona(ethylene glycol) (BS(PEG)9) and ferulic acid (FA) were tested to obtain water resistant films suitable for gas permeability characterization. Functional properties (mechanical and gas transfer properties) of gelatin‐based films were determined. Gelatin films cross‐linked with FA presented very good gas barrier properties (48 and 175 cm3.µm/m2.day.kPa respectively for O2 and CO2), compared to synthetic polymers, equivalent to polar polymer like nylon 6 or polyethylene terephthalate and better than non‐polar polymers like high density or low density polyethylene. Swelling ratio measurements in water displayed gelatin/FA films resisted to water without breaking during 4 h compared to 1.5 h for pure gelatin films. Films could support saturated water vapour environment at 20 °C during 15 days without breaking. Gelatin/PEG200 films presented very good permselectivity towards CO2 and O2 (14.5). This value was reduced to 8 when cross‐linked with FA, and to 4 after PEG200 addition, presenting still interesting level. All these results confirmed that gelatin is a promising biobased polymer to prepare food packaging films.