Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2023

Unlocking the microbial diversity and the chemical changes throughout the fermentation process of “hákarl”, Greenland shark

Höfundar / Authors: Snorri Páll Ólason (1), Sigurlaug Skírnisdóttir (1), Sophie Jensen (1), Guðmundur Stefánsson (1), Cecile Dargentolle (1), Viggó Þór Marteinsson (1,2)

Starfsvettvangur / Affiliations: 1. Department of Research and Innovation, Matís, 2. Faculty of Food Science and Nutrition, University of Iceland

Kynnir / Presenter: Snorri Páll Ólason

Hákarl is a unique traditional Icelandic product and is obtained by fermenting and drying Greenland shark (Somniosus microcephalus). The aim of the current study was to investigate the complex chemical and microbiome changes that occur during the fermentation and drying process. On an industrial scale, fresh and frozen shark meat was fermented for eight and seven weeks, respectively, and then dried for five weeks. The microbial and chemical changes were examined with 16S rRNA amplicon sequencing, selective plate counts, pH, trimethylamine N-oxide (TMAO), trimethylamine (TMA), dimethylamine (DMA) and water content measurements. The results showed that during the fermentation period, the pH increased from 6 to 9, while TMAO declined below the detection limit. Simultaneously, TMA and DMA levels increased. Total viable plate counts and specific spoilage bacteria increased during the fermentation but decreased during drying. Molecular analyses revealed gradual shifts in the bacterial community structure as fermentation progressed, dividing the fermentation process into three distinct phases that stayed rather similar throughout the drying. PCA analysis confirmed a correlation between the concentrations of TMAO, TMA and DMA to specific bacteria genera. The results indicate that the fermentation period can potentially be shortened and that starter cultures could be used to optimize the production process.