It was declared extinct in 1916 , but almost 100 years on it is being touted as a premium, sustainable crop for Peruvian farmers.

Peruvian Nacional cocoa is the rarest cocoa in the world, with only 30 people world wide licensed to buy it.

It is a heritage breed that can be grown beneath a canopy, and it's less nutrient intensive than commercial hybrid varieties, making it easier on the soil and more sustainable.

The Peruvian government has asked Tasmanian chocolatier Igor Van Gerwen, to talk to farmers about the benefits of the slower growing, better tasting, premium crop.

A remarkable discovery

Peruvian Nacional was originally discovered in Ecuador in the 1600s, before it was struck down by a mould called 'witches broom' and declared extinct by the World Cocoa Organisation in the early 1900s.

But in 2009 two Americans discovered 24 surviving trees on a plantation in a hidden valley of the Marañón River.

They belonged to Don Fortunato, who had no idea they were the long lost Peruvian Nacional breed, and was selling them as a commodity.

Tasmanian choclatier and owner of House of Anvers Igor Van Gerwen, says the cocoa was tested, and history was made.

"When you taste Fortunato No. 4, it is fantastic, very complex in flavour," he said.

"It's how chocolate would have tasted 100 years ago.

"It's got less bitterness because it's grown at a high altitude, so there are less tannins, so you can use more cocoa in your chocolate without it getting bitter."

Mr Van Gerwen says this variety is a more sustainable option than the commercially available hybrid cocoa grown in Africa and Asia.

"In Asia they grow hybrids which are very fast growing, very big fruit, but they don't have a lot of flavour," he said.

"Those varieties deplete the soils of nutrients.

"In broad terms they are grown in sterile environments, so all the trees need to be logged out to grow it.

"And at the same time those varieties take a lot of nutrients out of the soil - within seven years all the nutrients are gone.

"What the big companies do now is just shut the farm down and move to another area," he said.

Mr Van Gerwen says he has seen first hand the impact of commercial hybrid farming in Ghana.

"In Ghana a lot of the cocoa industry is moving from the north of the state to the west of the state, and the soils are really left with nothing," he said.

"There are still some small farms that grow the old fashioned way, which is under a canopy, and the old varieties grow slowly, so they don't deplete the nutrients."

The canopy Mr Gerwen refers to is a layered farming technique, where fruit trees form a canopy to protect the cocoa trees beneath, which in turn shade the coffee plants below.

All three crops are harvested by hand.

The cocoa beans grow inside a 'mulch', which is removed before roasting. ( Courtesy: Igor Van Gerwen )

A sustainable future

Mr Van Gerwen is one of only 30 people in the world licensed to buy the cocoa, which is grown at a secret location.

While cocoa has its origins in the Amazon rainforest, it is no longer a primary crop in Peru, but he and the Peruvian government would like to see that change.

"I was in Peru in March and I spoke to quite a few people in the industry, and they felt my passion for old varieties of cocoa," he said.

"Instead of starting to adopt the hybrid varieties, I feel that they should market themselves as a niche market, on old varieties.

"So the cocoa board in Peru has asked me to come to talk to farmers and convince them that there is more money in growing the Nacional breeds," he said.

"To convince them that there is more money involved in growing old breeds.

"We pay premium pricing for flavoursome varieties so in the end they will get paid more for their small farming crops."