A new study recently published in Finland points to the potential of plant cell wall polysaccharides (PCWP) as a base material for environmentally friendly food wrapping.
In their article in Trends in Food Science & Technology, co-authors Kirsi Mikkonen and Maija Tenkanen reveal that xylans and mannans could replace starch in sustainable plastics. The former are commonly found in agricultural and the latter in forest industry sidestreams such as cereal husks and pulp PCWPs.
“They are a remarkable, plentiful natural resource that occur in all plants and are not exploited yet,” Mikkonen told European Plastics News. “ [They are] much better to use than starch as they are not a human nutrient whose use could increase food prices.”
Mannans are used in animal feed and xylans are a byproduct of paper mills. An average mechanical pulp mill has the potential to recover 5,000 tonnes of xylans annaully, said Mikkonen.
Xylan and mannan PCWPs are not just an alternative to starch-based plastics, but possibly oil-based products as well, as and xylan- and mannan-based wrappings and trays show low oxygen and grease permeability and even high tensile strength.
The two researchers says that the films, whether biodegradable or edible (as they can be if produced accordingly), can be strengthened by crosslinking or blending with other polymers and nano-particles,
However, further research is needed as it is still unclear how this packaging material could be employed within the constraints of current technology.