Green plastics for food packaging 531 Polystyrene is derived from non-renewable resources, is non-degradable and for its processing blowing agents were used in the past that contributed to the depletion of the ozone layer. Paper-based products have a more favourable environmental perception but do not share the mechanical properties of polystyrene foams. It is well known that starch, containing sufficient moisture can provide stable foams. A step forward has been the introduction recently by Novamont of a new foamed tray based on starch particularly for the " McDonalds' type of applications. Apack has introduced another tray made from a baked starch formulation that has a coating of Eastar Bio aliphatic-aromatic copolyester Sainsbury, a leading retailer in the UK, has been packaging its organic fruit and vegetables in these starch-based materials by Apack Paperfoam has patented Paperfoam that is produced from a viscous suspension containing starch, cellulose fibres and water. The suspension injected into the mould. Due to the mould's temperature(c 200C) the starch granulate gelatinise and the water evaporates. The manufacturing cycle bakes from five seconds to two minutes, depending on wall thickness, from starch, natural fibres and water using an energy-efficient, one-step production technology. It can be recycled with paper and is biodegradable. Paperfoan combines a foamed inner structure with a smooth outer face and is applicable for a wide variety of uses. At present Paperfoam is used in the packaging of hand held electronic consumer goods, such as telephones, but not yet in food Other types of foamed products at different stages of development are blends of starch with poly vinyl alcohol-co-40%-ethylene), PVOH-40, a degradable rater resistant polymer that can be processed into viable alternatives to Ps foar packages via wafer baking technology, extrusion, or expanded-bead moulding and starch-based dough made by a baking process for various food containers Although one of the most versatile technologies for the production of starch based foam is via this type of baking process where a starch dough is heated under pressure to form a moulded foam product, these starch products are moisture sensitive and have poor mechanical properties. Both of these attributes can be improved by the inclusion of fibres and/or fillers in the dough mechanical and thermal properties rivalling those of polystyrene Deposites formulation. The resulting products are starch-based foam com 24.5.3 PHA in food packaging PHa properties show that it might be a very good alternative for conventional polymers in food contact packaging. However, when Monsanto bought the Biopol process in 1995 profitability still remained elusive. The approach with the most potential was to grow PHA in plants, modify ing the genetic make-up of the crop so that it could synthesise plastic as it grew and eliminate the fermentation process. However, it was found that producing one kilogram of PHA from genetically modified corn plants would require about 300% morePolystyrene is derived from non-renewable resources, is non-degradable and for its processing blowing agents were used in the past that contributed to the depletion of the ozone layer. Paper-based products have a more favourable environmental perception but do not share the mechanical properties of polystyrene foams. It is well known that starch, containing sufficient moisture, can provide stable foams. A step forward has been the introduction recently by Novamont of a new foamed tray based on starch particularly for the ‘McDonalds’ type of applications.21 Apack has introduced another tray made from a baked starch formulation that has a coating of EastarBio aliphatic-aromatic copolyester. Sainsbury, a leading retailer in the UK, has been packaging its organic fruit and vegetables in these starch-based materials by Apack.22 Paperfoam has patented Paperfoam that is produced from a viscous suspension containing starch, cellulose fibres and water. The suspension is injected into the mould. Due to the mould’s temperature (c. 200ºC) the starch granulate gelatinises and the water evaporates. The manufacturing cycle bakes from five seconds to two minutes, depending on wall thickness, from starch, natural fibres and water using an energy-efficient, one-step production technology. It can be recycled with paper and is biodegradable. Paperfoam combines a foamed inner structure with a smooth outer face and is applicable for a wide variety of uses. At present Paperfoam is used in the packaging of hand￾held electronic consumer goods, such as telephones, but not yet in food packaging.23 Other types of foamed products at different stages of development are blends of starch with poly(vinyl alcohol-co-40%-ethylene), PVOH-40, a degradable, water resistant polymer that can be processed into viable alternatives to PS foam packages via wafer baking technology, extrusion, or expanded-bead moulding24 and starch-based dough made by a baking process for various food containers.25 Although one of the most versatile technologies for the production of starch￾based foam is via this type of baking process where a starch dough is heated under pressure to form a moulded foam product, these starch products are moisture sensitive and have poor mechanical properties. Both of these attributes can be improved by the inclusion of fibres and/or fillers in the dough formulation. The resulting products are starch-based foam composites with mechanical and thermal properties rivalling those of polystyrene.26 24.5.3 PHA in food packaging PHA properties show that it might be a very good alternative for conventional polymers in food contact packaging. However, when Monsanto bought the Biopol process in 1995 profitability still remained elusive. 11 The approach with the most potential was to grow PHA in plants, modifying the genetic make-up of the crop so that it could synthesise plastic as it grew and eliminate the fermentation process. However, it was found that producing one kilogram of PHA from genetically modified corn plants would require about 300% more Green plastics for food packaging 531