Biopreservation of Atlantic salmon using lactic acid bacteria isolated from ready-to-eat seafood: Insight into antimicrobial activity, growth properties and effect on quality
Doctoral thesis
Permanent lenke
https://hdl.handle.net/11250/3132772Utgivelsesdato
2024Metadata
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Sammendrag
Today’s fast lifestyle and changes in dietary habits have increased the demand for ready-to-eat (RTE) seafood products. These products, rich in polyunsaturated fatty acids, proteins, essential amino acids, minerals, and vitamins, have proven beneficial to consumers’ health. At the same time, these products are described as highly perishable, challenging the food industry to maintain these characteristics with minimal processing while ensuring food safety. Traditional preservation strategies such as sterilisation, pasteurisation, and drying can ensure microbial inactivation but may have detrimental effects on these products' nutritional, functional and sensory properties. Thus, all efforts are put into finding a suitable treatment that will provide food safety and quality with minimal effect on physicochemical attributes. One of the options is biopreservation.
Biopreservation is a natural technology that uses microorganisms and/or their metabolites to secure food quality and safety with minimal or even improved effects on food's nutritional, functional and sensory attributes. Lactic acid bacteria (LAB) are good candidates for this technology because they are generally recognised as safe (GRAS), have antimicrobial activity against various spoilage and pathogenic microorganisms, and possess adaptive characteristics to different stress conditions.
The main goal of this project is to investigate the distribution of LAB among different seafood products and their potential use for the biopreservation of fresh RTE salmon. The selection of LAB for biopreservative purposes included their antimicrobial activity against pathogens commonly found in seafood products, such as Listeria monocytogenes, and their growth properties at different temperatures and processing conditions, such as different salt and liquid smoke concentrations. Almost one hundred tested LAB isolates showed variations in antimicrobial activity against Listeria strains and Escherichia coli, with the most effective belonging to the genera Carnobacterium and Leuconostoc. Further, ten selected LAB strains (five Carnobacterium and five Leuconostoc) were able to grow at refrigerated temperatures and different processing conditions (such as different salt and liquid smoke concentrations). Two out of ten possesses bacteriocin-like substances. Four LAB strains, classified as Carnobacterium maltaromaticum 35 and 55, C. divergens 468 and Leuconostoc gelidum 406, were selected to investigate their effect and biopreservative potential in fresh vacuum-packed (VP) RTE salmon fillets for 21/22 days at 4℃.
The selected strains showed adaptive characteristics to the conditions found in salmon fillets. They even dominated the natural microbiota present. Moreover, the selected LAB outcompeted Photobacterium, a genus described as a fish spoiler. The LAB strains did not negatively influence physicochemical properties and quality parameters such as ATP-degradation products and the formation of biogenic amines. The strain C. maltaromaticum 35 inhibited the growth of Listeria innocua during the 21-day storage period.
This research project showed that LAB isolated from seafood products is suitable for the biopreservation of fresh RTE salmon. This is especially important regarding limited studies in fresh salmon products, where even a small impact of LAB metabolism could affect the clear sensory profile of fresh salmon. Overall, this study provides a significant contribution to the industrial application of biopreservation of RTE salmon products.