Gas transfer properties of wheat gluten coated paper adapted to eMAP of fresh parsley

Gas transfer properties of wheat gluten (WG) coated paper and their ability to fulfil the requirements in eMAP of fresh parsley were studied. Permeation of gases through WG-paper was demonstrated to be RH-dependent and closely related to structural modification in the WG layer. Formation of micro-cracks was evidenced in dry conditions; but when increasing RH, plasticisation occurs within the protein layer and micro-fractures were reduced until disappearance. This reversible phenomenon allowed the WG-layer to recover its integrity at RH higher than 70%, and the WG character to be expressed in such conditions. When used at 20 °C and 80% RH as part of the packaging of parsley, modified atmosphere was created and a steady state of 11 kPa O₂ and 4.5 kPa CO₂ was reached after 45 h. In such conditions, the overall quality of parsley leaves remained acceptable during 8 days, with only 28% loss of chlorophyll.