Packaging cultivated mushrooms with the material allows storage at 20°C for four days, compared to one day using conventional synthetic film, according to France's Institute for Agronomy Research (INRA). The organisation's research unit in Montpellier developed the bioactive packaging as a means of increasing the short shelf life of mushrooms.
Cultivated mushrooms packaged in trays give off high levels of moisture and are sensitive to carbon dioxide, both situations that rapidly give rise to opening of the cap and discoloration.
The synthetic films currently used to package mushrooms in trays do not solve these problems. The poor permeability of synthetic films to water vapour causes condensation and the appearance of brown marks on the mushrooms.
Preliminary studies by a sister unit in Avignon had demonstrated the usefulness of gluten films for the storage of plant products, enabling the installation of an atmosphere with low levels of both O2 and carbon dioxide. However, the weak mechanical properties of the materials did not allow their use for packaging.
The unit in Montpellier developed a composite packaging material made up of paper impregnated with wheat gluten. The packaging is biodegradable, gas selective and permeable.
The use of paper as a substrate considerably improves the mechanical properties of the wheat gluten film, while still ensuring its biodegradability. Packaging cultivated mushrooms with this composite material corresponds to "modified atmosphere packaging" which induces an atmosphere containing low levels of both O2 and carbon dioxide and prevents condensation.