Unlocking the microbial diversity and the chemical changes throughout the fermentation process of “hákarl”, Greenland shark
Hákarl is a unique traditional Icelandic product and is obtained by fermenting and drying Greenland shark (Somniosus microcephalus). However, little is known about the chemical and microbial changes occurring during the process. In this small-scale industrial study, fresh and frozen shark meat was f...
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| Published in: | Heliyon Vol. 9; no. 11; p. e22127 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
England
Elsevier Ltd
01-11-2023
Elsevier |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Hákarl is a unique traditional Icelandic product and is obtained by fermenting and drying Greenland shark (Somniosus microcephalus). However, little is known about the chemical and microbial changes occurring during the process. In this small-scale industrial study, fresh and frozen shark meat was fermented for eight and seven weeks, respectively, and then dried for five weeks. During the fermentation, trimethylamine N-oxide levels decreased to below the limit of detection within five weeks and pH increased from about 6 to 9. Simultaneously, trimethylamine and dimethylamine levels increased significantly. Total viable plate counts, and specific spoilage organisms increased during the first weeks of the fermentation period but decreased during drying. Culture-independent analyses (16S rRNA) revealed gradual shifts in the bacterial community structure as fermentation progressed, dividing the fermentation process into three distinct phases but stayed rather similar throughout the drying process. During the first three weeks of fermentation, Photobacterium was dominant in the fresh group, compared to Pseudoalteromonas in the frozen group. However, as the fermentation progressed, the groups became more alike with Atopostipes, Pseudomonas and Tissierella being dominant. The PCA analysis done on the chemical variables and 16S rRNA analysis variables confirmed the correlation between high concentrations of TMAO and Pseudoalteromonas, and Photobacterium at the initial fermentation phase. During the final fermentation phase, correlation was detected between high concentrations of TMA/DMA and Atopostipes, Pseudomonas and Tissierella. The results indicate the possibility to shortening the fermentation period and it is suggested that the microbial community can potentially be standardized with starter cultures to gain an optimal fermentation procedure.
•Bacterial counts reached a maximum after 2–3 weeks of fermentation.•TMAO levels decreased early in the process while TMA and DMA increased.•TMAO reducing bacteria were dominant in the initial phase of fermentation.•Bacteria using TMA, urea and ammonia were abundant in the mid fermentation phase.•Ready-to-eat hákarl frozen before fermentation contained less TMA and DMA. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 2405-8440 2405-8440 |
| DOI: | 10.1016/j.heliyon.2023.e22127 |