Development of starch-based peelable coating for edible packaging

This research characterised properties and stability of starch-based peelable coating film layers via mould dipping. Different ratios between rice starch (RS) and hydroxypropyl cassava starch (HS) containing agar blends were characterised for fluid rheology and properties of solid films. Layer-by-layer mould dipping in starch blend suspensions produced peelable shells. Rheology indicated that formability of thin-film layer on solid surface subsequently affected integrity of the shells. HS highly adsorbed water which plasticised matrices giving lower relaxation temperature (~10 °C) than RS and caused shrivelling and non-stable shell structures. RS increased crystallinity and non-homogeneity of films and reduced network flexibility and light transmission. IR spectra indicated modified hydrophobicity and hydrogen bonding of starch blends which governed water and oxygen permeability. Higher RS ratios significantly increased crystallinity which affected physical, mechanical and barrier properties during storage for three months. Findings indicated that HS provided flexibility and stability while RS improved formability of peeled shells.