Application of hurdle technology for the shelf life extension of European eel(Anguilla anguilla)fillets

Fresh fish,and especially fatty species,are highly perishable due to oxidative deterioration of fish flesh and the elevated microbial load on fish surface.The implementation of a variety of“mild hurdles”may significantly decrease the rates of fish chemical degradation and microbiological spoilage,by better retaining the initial quality,compared to more intense preservation techniques.The aim of this work is the comparative study of different,single or combined,treatments at 15℃on the quality and shelf life of chilled eel fillets.Fish fillets were treated using osmotic solutions consisting of glycerol(30%–40%–45%)and 5%NaCl with and without former antioxidant impregnation by using Rosemary Serum.In all cases,water activity decreased to approximately 0.90 after 420 min of osmotic treatment.Untreated and osmotically treated fish fillets were subsequently stored at 4℃and their stability under chill conditions was assessed based on microbial growth and oxidative deterioration.Microbial growth of treated samples was significantly delayed,especially due to the osmotic step(OS)and the derived water activity decrease.Lipid oxidation,a major cause of rejection for fatty fish such as eel,was greatly inhibited in treated fillets,owing to both‘hurdles’,aw lowering(OS)and antioxidant impregnation with rosemary serum(RS/OS),showing the synergistic effect of these successive procedures.Shelf life of treated eel fillets exhibited a more than 10-fold increase,as compared to the untreated samples,based on chemical composition and a 2 to 3-fold shelf life improvement,in terms of microbial growth.

Integrating omics technologies for improved quality and safety of seafood products

An essential aspect of product quality of aquatic foods is the rapid and accurate identification of bacterial species.From this perspective omics technologies prove to be very useful in the assessment of the quality and safety of seafood products.Such technologies can identify and detect low levels of contamination by pathogenic and spoilage bacteria and can be used to study the effects caused by processing and storage of seafood products.The integration of food processing with the monitoring of the microbial characteristics using conventional microbiological assays,coupled to molecular techniques may establish the baseline for the development of quicker and more sensitive and reliable methods for seafood safety screening.The use of combined omics technologies,including metagenomics,proteomics and metabolomics,coupled to conventional quality indices such as colour,texture and flavour offer a new tool for novel processing optimization to ensure seafood quality.The aim of this brief review is to outline how omics technologies can generate novel tools for integration into seafood processing and quality control.Considering that the main aspect of the review is the improvement of safety and quality of the final product,from production to consumption,emphasis is given to microbial identification and metabolite detection,the evaluation of the allergenic capacity of fish and seafood and optimization of postharvest processing.Deployment of omics for identification of potential microalgal products of relevance to seafood quality and safety is also considered.

Slurry ice as an alternative cooling medium for fish harvesting and transportation:Study of the effect on seabass flesh quality and shelf life

The objective of the study was to investigate the efficiency of slurry ice during harvesting and transportation of European sea bass(Dicentrarchus labrax)to retain flesh quality and extend shelf life,compared with conventional flake ice.Fish was slaughtered and transported in different mixtures of slurry ice and conventional flake ice(C:slaughtered and transported in 100%flake ice-Control samples,SC:slaughtered in 100%slurry ice and transported in 100%flake ice,S50:slaughtered and transported in 50%slurry ice-50%flake ice,S100:slaughtered and transported in 100%slurry ice)and subsequently stored under controlled isothermal conditions at 0℃for shelf life modelling and flesh quality evaluation(proteolytic enzymes).The replacement of conventional flake ice with slurry ice as a slaughtering method led to improved quality stability during subsequent refrigerated storage and shelf life extension,in terms of microbial growth,flesh quality and sensory degradation of fish.Based on microbial growth,the shelf life of C samples was found to be 19 days,whereas the shelf life of S50/S100 and SC was 21 and 25 days,respectively,showing that the replacement of flake ice with slurry ice resulted in 2–6 days shelf life extension of whole sea bass stored at 0℃.The use of slurry ice at slaughter and flake ice in transportation was accompanied by low activities and late peaks of all four enzymes that is expected to lead to delayed proteolytic degradation and extended freshness.

Bacterial community in response to packaging conditions in farmed gilthead seabream

The objective of this study was to evaluate the effect of modified atmosphere packaging(MAP)on fish skin,gills and intestines bacterial microbiome.Whole gilthead seabream was packed aerobically or under modified atmospheres(60%CO_(2),30%N_(2),10%O_(2))and stored isothermally at 0℃.Next Generation Sequencing(NGS)analysis was applied for the characterization of fish microbiome on fish skin,gills,and intestines initially(time of packaging,1 day after harvesting)and after 10 days of isothermal storage at 0℃.NGS results indicated statistically significant differences in families’richness and diversity in the tested fish tissues between aerobic and MAP packaging during storage at 0℃.The most persistent bacteria were Proteobacteria for both packaging types.For fish skin microbiota,the initially prevailing families were Comamonadaceae,Enterobacteriaceae and Moraxellaceae while in the intestines Comamonadaceae,Anaplasmataceae,Bacillaceae and Enterobacteriaceae were the dominant bacteria.At the end of storage period,the fish microbiota was dominated by psychotropic and psychrophilic families(Pseudoalteromonadaceae,Psychromonadaceae,and Shewanellaceae),while families such as Comamonadaceae were persistent under MAP conditions.By 8 days of fish storage at 0℃,МАРsamples exhibited higher sensory scorings than the respective aerobically stored fish,indicating better retention of fish freshness and fish quality attributes under MAP.Based on the results of the study,MAP modified significantly the microbiological status and extended the shelf life of fish.NGS was a powerful tool that provided a more complete assessment compared to a culture-based analysis.

Editorial:Improving fish from catch to the consumer:Post harvest handling,processing,packaging,transportation and storage

Aquaculture is the fastest growing food producing sector,accounting for almost 50%of the animal protein consumed globally,with the expectation that it will rise to 65%by 2030,due to the increasing emphasis on fish products as important components of a healthy diet.However,EU production is stagnating with approximately 60–65%of European demand for fish products being imported(EUMOFA,2021).The reason for this is complex and the sector faces a number of challenges.

Hurdle technology for fish preservation

Fresh fish is a highly perishable product due to the chemical composition of fish flesh and the high microbial load on fish surface.The natural microflora that is more adopted to low temperatures results also in lower thermal bacterial shock from natural temperature to the preservation temperature range.The development of new fish processing(e.g.high hydrostatic pressure,osmotic dehydration,high-intensity pulsed light)and packaging(e.g.modified atmospheres,active and intelligent packaging)methods or novel combinations of existing technologies is sought by the industry in the pursuit of producing alternative products,achieving shelf life extension,and management and reducing food waste.In 2014,processed fish was among the most active new product categories.The lack of dissemination of validated laboratory results for the seafood industry is one of the major issues preventing the uptake of minimal and nonthermal processing for fresh fish.However,it has been reported that some bacteria become more resistant under stress(e.g.psychrotolerant lactobacilli).At the same time,the application of some processing methods(e.g.thermal processing)may affect significantly the nutritional and sensory profile of the target food product.The application of several“soft hurdles”may reduce the rate of fish deterioration and spoilage caused by microbial growth.The objective of this article is to review the preservative effect of alternative hurdles on fish quality and shelf life,focusing on recent,combined applications.