Characterization of Microbiological Quality of Whole and Gutted Baltic Herring.

Jaana Huotari,Kaisu Honkapää,Irina Tsitko,Hanna-Leena Alakomi

doi:10.3390/foods11040492

Jaana Huotari, Kaisu Honkapää + Show 2 more

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https://doi.org/10.3390/foods11040492

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Abstract

There is growing interest in Baltic herring (Clupea harengus membras) and other undervalued, small-sized fish species for human consumption. Gutting or filleting of small-sized fish is impractical; hence, the aim of this study was to explore the suitability of the whole (ungutted) herring for food use. The microbiological quality of commercially fished whole and gutted herring was analysed with culture-dependent methods combined with identification of bacterial isolates with MALDI-TOF Mass Spectrometry and culture-independent 16S rRNA gene amplicon sequencing. Whole and gutted herring had between 2.8 and 5.3 log10 CFU g−1 aerobic mesophilic and psychrotrophic bacteria and between 2.2 and 5.6 log10 CFU g−1 H₂S-producing bacteria. Enterobacteria counts remained low in all the analysed herring batches. The herring microbiota largely comprised the phyla Proteobacteria, Firmicutes, and Actinobacteria (71.7% to 95.0%). Shewanella, Pseudomonas, and Aeromonas were the most frequently isolated genera among the viable population; however, with the culture-independent approach, Shewanella followed by Psychrobacter were the most abundant genera. In some samples, a high relative abundance of the phylum Epsilonbacteraeota, represented by the genus Arcobacter, was detected. This study reports the bacterial diversity present in Baltic herring and shows that the microbiological quality was acceptable in all the analysed fish batches.

Highlights

Demand for fish and fish-based products is rising globally, while many of the undervalued fish species remain underutilized in food production
The bacterial counts of whole and gutted herring were analysed at ten different times representing different seasons (Table 2 and Table S1)
2.8 log10 CFU g−1 to 5.3 log10 CFU g−1

Summary

Introduction

Demand for fish and fish-based products is rising globally, while many of the undervalued fish species remain underutilized in food production. The annual catch of Baltic herring (Clupea harengus membras) in Finland is approximately 100 million kilograms, making herring the most important fish species in the Finnish commercial marine fish catch by volume [1]. Herring is considered a nutritious and sustainable alternative to other protein foods for human consumption [3] and offers an attractive raw material for value-added food products [4]. Due to the small size of Baltic herring, gutting or filleting is not feasible for most of the catch. Processing the whole fish into the final product would enable the use of the small, undervalued fish as food [4]. The microbiological quality of the whole small-sized herring requires investigation

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