A burger with cheese, relish and algae could become a standard fast food combo, hope inventors working on biodegradable cartons built from self-regenerating seaweed.

The Austrian-based team make Alginsulate, a packaging or insulating foam to replace expanded polystyrene from dried brown algae. Vast tangled clots of this grow in seas worldwide. Either the whole weed or its gummy cell-wall constituents called alginates can be puffed up into a spongy foam using blasts of air, and moulded into trays or other shapes.

"The fast food sector in China has indicated great interest," says Bettina Reichl of Verpackungszentrum Graz, the firm researching the process alongside the Graz University of Technology. The demand for biodegradable packaging in China has rocketed since many towns and cities prohibited fast-food containers made of polystyrene foam at the end of 2000. In Shanghai alone, half a million such containers are used daily, says Reichl.

"It's worth exploring," agrees Susan Selke who studies biodegradable packaging at Michigan State University in East Lansing. But in order to be successful, eco-friendly packages have to rival the cost of existing types, she points out.

Biodegradables must also be accompanied by a composting system if they are to be environmentally beneficial, says Selke. Dry landfill sites in the US, for example, do not encourage composting; degradation is slow and releases the greenhouse gas methane. Some European countries, however, benefit more from biodegradables as they collect and dispose of organic waste separately.

Other starch-based biodegradable packages, made from corn and potatoes, smelled too attractive to mice and insects, another potential pitfall for the weed wrap. "You could have the wires in your electronics chewed to pieces," says Selke.

Existing polystyrene foams are made from oil derivatives. Brown algae are harvested from off-shore beds to extract alginates which are widely used industrially, for example as thickeners or stabilizers in ice cream and hand lotion. Alginates woven into a gauze are also used as dressings for burns and wounds.

The company, which has set up a pilot plant for Alginsulate, hopes the foam could also be used to package transported goods and as an alternative to flexible plastic foams in car seats and mattresses. Experiments suggest that the processed weed is also fire-resistant, it claims.

Source: www.nature.com