(TDB) - A group of Australian scientists have brewed a beer from 220-year-old yeast salvaged from a shipwreck, which they claim to be the ‘world’s oldest beer’.

The Sydney Cove had been en route from Calcutta to Sydney when it ran aground and sank off the tiny Preservation Island in Bass Strait near Tasmania in February 1797, taking with it 7,000 gallons of alcohol.

While the wreck was largely picked clean, for almost two centuries the beer onboard remained hidden, sealed beneath a layer of sand and sea grass, as reported by Australia’s ABC. The conditions meant that the organic matter in the beer was unusually preserved until it was discovered in 1990.

“It virtually sealed everything in, there was no oxygen getting in and it was completely intact,” Mike Nash, a marine archaeologist who salvaged the wreck, told the Australian Broadcasting Corporation (ABC).

David Thurrowgood, a chemist-turned-conservator, came across the beer bottles salvaged from the wreck nearly two years ago in storage at a Tasmanian museum, and wondered if the centuries-old liquid could still contain real yeast.

“At that point I was getting really excited,” Mr Thurrowgood told ABC. “That gave us a chance to possibly have access to the oldest beer in the world. I thought we might be able to culture that yeast and recreate beer that hasn’t been on the planet for 220 years.”

While some experts doubt that yeast is capable of surviving any longer than 10 years, two of the samples of beer taken from the wreck and decanted twenty years ago were successfully revived by a team led by Thurrowgood and Anthony Borneman, a yeast specialist from the Australian Wine Research Institute.

A detailed DNA analysis of the yeast identified Brettanomyces, a non-spore forming genus of brewers’ yeast not used in modern commercial brewing, but that was common to old-style brewing. Also present was Saccharomyces, another form of yeast used for brewing and baking, but unlike modern forms of the yeast. This yeast was hybrid that scientists said sat closest on the yeast family tree to Trappist ale, made by monks in Belgium.

The 20 year gap between the beer being decanted and its yeast revived did raise questions that perhaps the beer had been contaminated in order for the yeast to come back to life. Howver Borneman believes there are too many coincidences for that to be the cause of their success.

“We’ve got two samples, the same bottle, both decanted and then kept apart,” he said. “So either there was a very specific contamination event 20 years ago when they decanted it into the two samples, both samples got equally contaminated with our hybrid Saccharomycesstrain and our beer-brewing Brettanomyces strains … then they were locked away for 20 years and both stayed viable. Or, the strains were in the bottle.”

Thurrowgood agrees adding: “We think we’ve got a yeast that hasn’t been seen for at least 220 years”.

Thurrowgood has since produced a homebrew using the yeast based on a common English ale recipe which has been named Preservation Ale, after the island where the Sydney Cove sank.