Researchers said that the bacteria had “interesting potential applications” for use in food and beverages dues to their high stress tolerance and, therefore, potential stability in food and non-food matrices.
The four species of live lactic acid bacteria isolated were Pediococcus damnosus, Lactobacillus malefermentans and Lactobacillus backii (all highly adapted to growing in beer and in association with brewing yeast).
The fourth species, Lactobacillus kisonensis, was only discovered a few years ago from a traditional fermented vegetable product in Japan.
19th century beer anyone?
Some of the bacteria were capable of producing viscous sugar polymers tentatively identified as beta-glucan, and VTT said that this sugar polymer protected bacterial cells against environmental stresses and may have preserved the beer.
Dead yeast cells in the beer appeared to be Saccharomyces cerevisiae or ‘brewer’s yeast’, while others resembled the Dekkera yeast characteristic of lambic (Belgian style) beer. No living yeast cells were found, but trace amount of yeast DNA could be detected from one of the bottles.
Annika Wilhelmson, VTT key account manager, said that the isolated bacteria provided interesting model organisms to understand and improve long-term survival of non-spore-forming bacteria.
Since 2010, VTT received funding from the Government of Åland to study the composition of the shipwreck beer and identify the type of yeast used to brew it.
The researchers aimed to show what an early 19th-century beer was like, and whether its production process could be reverse engineered and the beer replicated, as well as isolating living microbes.
Golden liquids in the bottles were identified as beer due to the presence of malt sugars, aromatic compounds and hops typical of beer, and chemical analyses showed it could originally have featured hints of rose, almonds and cloves.
Enigma of ‘burned flavour’
A pale golden colour indicated that the beers were made from unroasted malt, with the VTT researchers unclear as to whether a resultant “burned flavour”indicated that heating during the mashing stage was not properly under control, although it was possible that consumers in the 1800s appreciated a smoky flavour.
The beers were probably made from grain – barley or wheat or a combination of the two. Hops, of a variety typical of a couple of centuries ago, had been added before boiling the wort.
The Government of Åland owns the research results, and said that work would continue in collaboration with VTT. Spokesman Jan-Ole Lönnblad said that he hoped continued research would lead to exciting new possibilities for food and health applications.
