The effect of high pressure treatment (HPP) (150 MPa and 300 MPa for 15 min) and cooking on quality of Atlantic salmon based on microbial activity, lipid oxidation, fatty acid profile, color and texture during 6 days of storage was studied. High pressure and cooking significantly (p <0.05) reduced microbial growth. The 300 MPa treatment and cooking showed higher L∗ and b∗ values but lower a∗ values for dark muscle compared to control and samples treated at 150 MPa. An increase in pressure resulted in an increase in hardness, gumminess and chewiness parameters, and a decrease in adhesiveness compared to control and cooked samples. Whereas cooking and 150 MPa led to similar oxidation development as control in dark muscle, the 300 MPa treatment effectively reduced the samples susceptibility to oxidation. Fatty acid profile of cooked Atlantic salmon dark muscle showed significantly (p <0.05) lower amounts of total saturated, n−3 Polyunsaturated fatty acids (PUFA) and n−6 PUFA and significantly (p <0.05) higher amounts of monoenes than HPP treated samples during the entire storage period. However, the most important finding of this study was that there was no significant (p > 0.05) difference between control and HPP treated samples in terms of total saturated, monoenes, n−3 PUFA and n−6 PUFA fatty acid profile. This demonstrates that HPP is a very mild process in terms of its effect on fatty acids.
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Fish protein isolates (FPI) from cod muscle were studied at pH 9 and 11. Thermo-reversible gels, stable at and below room temperature could be produced at both pH values. Application of low shear stress to the gels led to an initial elastic response followed by a power-law deformation (creep) at both pH. Above a critical shear stress gels fractured and flowed regularly with a viscosity of about 0.05 Pa s.
Strain – stress curves were recorded using both flow and oscillatory measurements. For all systems strain-hardening was observed followed by fracture. Fracture occurred at approximately the same deformation, but the amplitude of strain-hardening and the yield stress decreased with decreasing rate of the stress ramp. Results obtained from oscillatory shear at 1 or 0.1 Hz were close to those obtained with continuous shear during the fastest stress ramps.
The structure of the gels was investigated using confocal laser scanning microscopy and turbidity measurements.
Cultivation and culture-independent techniques were used to describe the geothermal ecosystem of the Blue Lagoon in Iceland. The lagoon contains both seawater and freshwater of geothermal origin and is extremely high in silica content. Water samples were collected repeatedly in summer and autumn in 2003 and 2005 and in winter 2006 were analyzed for species composition. The study revealed the typical traits of an extreme ecosystem characterized by dominating species and other species represented in low numbers. A total of 35 taxa were identified. The calculated biodiversity index of the samples was 2.1–2.5. The majority (83%) of analyzed taxa were closely related to bacteria of marine and geothermal origin reflecting a marine character of the ecosystem and the origin of the Blue Lagoon hydrothermal fluid. A high ratio (63%) of analyzed taxa represented putative novel bacterial species. The majority (71%) of analyzed clones were Alphaproteobacteria, of which 80% belonged to the Roseobacter lineage within the family of Rhodobacteraceae. Of seven cultivated species, the two most abundant ones belonged to this lineage. Silicibacter lacuscaerulensis was confirmed as a dominating species in the Blue Lagoon. One group of isolates represented a recently identified species within the genus of Nitratireductor within Rhizobiales. This study implies an annually stable and seasonally dynamic ecosystem in the Blue Lagoon.
A pollock protein hydrolyzate was used for enrichment of the live feed offered to halibut larvae from the onset of exogenous feeding and the effects of treatment on selected innate immune parameters studied. The effects of treatment on the bacterial community structure of larvae were furthermore studied using the PCR – DGGE method. C3 and lysozyme were identified in larvae already at the onset of first feeding and low concentrations of IgM detected at this stage indicate maternal origin. Endogenous production of IgM was validated in the gastrointestinal tract of larvae from 29 days post onset of first feeding, with similar concentrations found in both groups. Feeding the peptide-enriched live feed stimulated production of lysozyme and affected the distribution of C3 in larval tissue but survival and normal development of halibut larvae were not affected by the treatment. Vibrio sp. and Pseudoalteromonas sp. dominated the bacterial community of larvae from both groups and peptide enrichment of the live feed was not found to affect the bacterial community structure associated with surface sterilized larvae.
Peeled, headed or whole shrimp (Pandalus borealis) was dried in a heat-pump dryer at -2-0 ℃ and 20 ℃, respectively, and desorption isotherms characterizing the dehydration property of each shrimp sample group were determined. Desorption isotherms of shrimp handled differently and dried at different temperatures (-2-0 ℃ or 20 ℃) could be well described by Oswin's model (() 1 wnwa Xa a = -). The regression model of peeled, headed or whole shrimp was established, which is reliable for predicting the desorption isotherms of shrimp undergoing heat-pump drying. The handling methods of shrimp exhibit measurable influence on desorption isotherms of shrimp, whereas drying temperature (-2-0 ℃ or 20 ℃) has little influence on the constants of a and n in Oswin's model, of whole shrimp, even though it has certain influence on these constants of peeled and headed shrimp. For heat-pump drying, headed shrimp may have a better stability than peeled or whole shrimp due to the best stability.
Persistent organic pollutants (POPs) are readily detected in biological samples at remote sites in the Arctic and sub-Arctic due to long-range transport from source areas. The aim of this study was to investigate the presence of POPs, polybrominated contaminants and their metabolites in guillemot (Uria algae) eggs from Iceland, the Faroe Islands, Norway and Sweden to assess spatial trends of these compounds in the Arctic and sub-Arctic areas of Europe. Egg samples were extracted, and cleaned for chemical analysis. Concentrations of PCBs, 4,4′-DDE and β-HCH were an order of magnitude higher in eggs from the Baltic Proper compared to eggs from the North Atlantic. Concentrations of HCB were of the same magnitude at all sites, ranging from 160 to 520 ng / g fat. Concentration of BCPS was 100 times higher in eggs from the Baltic compared to eggs from the North Atlantic and therefore seems to be special regional problem. Concentrations of PBDEs were lower in eggs from the North Atlantic compared to eggs from the Baltic Proper but the difference was not as large as for PCBs and 4,4′-DDE. HBCDD showed the same spatial trend as PCBs, where the concentrations in eggs from the Baltic Proper were an order of magnitude higher than in eggs from the North Atlantic. OH-PCB and MeSO2-PCB metabolites of PCBs, showed the same trend as the parent compounds while spatial trends of MeSO2-DDE and OH-PBDEs, metabolites of 4,4′-DDE and PBDEs, respectively, differed from the trend of the parent compounds. This may be due to two factors; firstly, the limited ability of birds to metabolize DDT, and secondly, to natural production of OH-PBDE, respectively. Guillemot is suggested as a monitoring species for circumpolar monitoring.
Applications of Decision Support Systems (DSSs) in the food industry, and in particular the seafood industry, are discussed. The amount of data recorded in the food industry has increased greatly in the last decade, parallel to descending cost of data recording through automation and computer systems. The data can be used to fulfill the demands of consumers that want information on their food products, such as origin, impact on the environment and more. By using traceability this flow of data can be used for decision support. Many fields within food processing can gain from using DSS. Such fields include for example lowering environmental impact of food processing, safety management, processing management and stock management. Research and development projects that the authors have taken part in and the following implementations of software solutions are discussed and some examples given of practical usage of DSS in the food industry as a result of such work.
This chapter discusses the potential of fish protein hydrolysates (FPH) as a food antioxidant and bioactive ingredient to combat oxidative processes in living systems. The effect of hydrolysis and enzymes on flavor of FPH and the processing techniques to reduce off-flavors and odors of FPH are described. The antiproliferative and immunomodulatory activities of FPH are also discussed.
Aims: To assess the effects of bacterial treatment at the earliest stages of cod rearing on the microbial load, larval development and performance, testing three bacterial strains (Carnobacterium divergens V41, Arthrobacter sp. and Enterococcus sp.) in vivo that were previously shown to have inhibitory potential towards fish pathogens in vitro.
Methods and Results: A bacterial mixture was added eight times to the rearing water from the prehatch to the mid-larval stage (a 38-day period). Microbiological analysis of ova, larvae and rearing water was performed regularly. Larval performance and development were evaluated by survival rate, hypersalinity tolerance and physiological measurements. Different larval survival rates were observed within and between treatments, and possibly explained by variations in larval microflora and established probionts. Larvae from one silo, which had been bathed in the bacterial suspension, showed the highest survival rate (42 · 1%), lowest Vibrio levels, and were significantly heavier (19 · 3%) and more stress tolerant than control larvae (P<0 · 01). This coincided with the intestinal establishment of two of the tested bacteria.
Conclusions: Arthrobacter and Enterococcus strains added regularly to the rearing water from the postfertilized egg stage can be established in larval gastrointestinal tract. The Enterococcus strain was associated with increased larval growth, performance and microflora control, indicating its probiotic nature.
Significance and Impact of the Study: Regular application of autochthonous probionts may promote larval welfare, development and stress tolerance at early stages, hence increasing production yield in intensive cod larviculture.
In order to study the possible interactive effects of salinity and photoperiod on growth, feed conversion, and blood chemistry in juvenile halibut, 2,604 (initial mean weight 26.8 g ± 0.2 SEM) juvenile halibut were exposed to six different combinations of salinities (13, 21 , or 27 ‰) and photoperiods [continuous light, C and simulated natural photoperiod (65 ° N), SNP] for 129 days. Improved (10–20%) growth and 10–24% higher feed conversion efficiency were observed at low and intermediate salinities compared to the high salinity groups. Improved feed conversion efficiency (20%) and temporary growth enhancing effects (10%) of continuous light were observed, but effects faded out as day length in the simulated natural photoperiod group increased. No interactive effects of photoperiod and salinity on growth feed conversion or measured blood chemistry variables (blood sodium, pH level, haematocrit, bicarbonate content, and total carbon dioxide). It is suggested that juvenile Atlantic halibut should be reared at low and intermediate salinities and at continuous light, as this will improve growth and increase feed conversion efficiency.