Greenie caffeine addicts now have the option of buying freshly roasted coffee in foil bags that can be safely buried in the garden or compost heap.

Christchurch coffee roaster Caffe Prima believes it has achieved a world first with its fully compostable foil bags made from wood pulp and corn starch by Hamilton-based Convex Plastics.

The new Econic coffee packets to be launched next week started to soften after a fortnight when they were tested at a Waikato bark composting facility. After 14 weeks they had almost completely disappeared with only small fragments left in the soil.

Caffe Prima owner Geoff Johnson says although compostable bags have been used for instant coffee, it was a little trickier coming up with packaging suitable for freshly roasted beans and ground coffee.

"When you roast coffee the beans expel CO2 and continue to do that as they age... unless you leave the coffee for four or five days before you bag it and then you lose flavour."

To prevent them blowing up as the carbon dioxide is released, foil packets of fresh coffee have a plastic one-way valve.

Instead of valves the fully compostable Econic bag incorporates vents that are activated by internal pressure to release the gas.

Johnson says fresh coffee consumption has risen 20 per cent a year for the last five years, resulting in a dramatic increase in packaging waste and he wanted to do something about it.

Caffe Prima uses about 90,000 foil bags annually. "We're a medium-sized player so there's millions (of foil bags) going out every year in New Zealand. We thought 'what should we be doing to be better corporate citizens?'"

The company experimented with paper bags, but the metal tie used to seal them was not compostable, so the company looked for other alternatives.

A rebranding exercise seemed like a good time to introduce the Econic bags made by laminating together three layers of film internationally tested to a British Standard for composting and biodegradability. The foil look is achieved by spraying the middle cellulose layer with an aluminium coating.

Caffe Prima, established in 1995, contract roasts for a wide range of customers, including the office supplies market and Johnson says that over the past decade there has been a definite shift to using freshly roasted coffee in work places.

"It has moved from instant to freshly roasted ground coffee, and now there's a move towards having espresso machines in offices to produce 'bean to cup' coffee rather than making it with a plunger. "

Johnson says that customers are excited by the prospect of being able to compost their coffee packets, and if they want to be really "green" they can fill them with coffee grounds and add some nutrients to the soil as well.