Salmon Samples Research Articles

Simultaneous and Fast Determination of Malachite Green, Leucomalachite Green, Crystal Violet, and Brilliant Green in Seafood by Ultrahigh Performance Liquid Chromatography–Tandem Mass Spectrometry

A new procedure has been developed for the simultaneous analysis of malachite green (MG), leucomalachite green (LMG), crystal violet (CV), and brilliant green (BG) in seafood using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure and subsequent determination by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry in <5.5 min. The developed method was validated at 2, 10, 25, and 100 μg kg−1, obtaining recoveries in the range of 48–112 %, with repeatability and interday precision values (expressed as relative standard deviation) ≤17 and ≤24 %, respectively. Matrix effect was evaluated for different types of seafood (shrimp, salmon, and trout), indicating that shrimp can be chosen as representative matrix for the determination of the selected dyes, except for LMG. Limits of quantification (LOQs) were <0.5 μg kg−1, which were always below the minimum required performance limits established by the European Union. The decision limit (CCα) and detection capability (CCβ) values were also estimated in the three matrices evaluated, and CCβ ranged from 0.46 to 1.22 μg kg−1. Finally, several types of seafood were analyzed, and some dye residues (MG, CV and BG) were detected in a salmon sample.

Detection of frozen-thawed salmon (Salmo salar) by a rapid low-cost method

The aim of this study was to evaluate a rapid low-cost system based on impedance spectroscopy as an alternative method to differentiate between fresh and frozen-thawed salmon. Samples of fresh salmon and others submitted to freezing at −18°C or to 2 freezing cycles, kept in frozen storage for different times, were analysed. In general, no significant differences in moisture, total volatile basic nitrogen, pH, texture parameters, K1 value, or microbial counts between the different samples were observed. This revealed that the freezing process, storage time or number of freezing cycles did not affect the physico-chemical parameters of fish samples, except for water holding capacity, which was significantly lower in all frozen samples compared with fresh salmon. The results showed that impedance spectroscopy was unable to differentiate between different storage times under frozen conditions; however, this technique could be a useful tool to detect fish submitted to freezing process.

Age and fine-scale marine growth of Atlantic salmon post-smolts in the Northeast Atlantic

Abstract Jensen, A. J., Ó Maoiléidigh, N., Thomas, K., Einarsson, S. M., Haugland, M., Erkinaro, J., Fiske, P., Friedland, K. D., Gudmundsdottir, A. K., Haantie, J., Holm, M., Holst, J. C., Jacobsen, J. A., Jensås, J. G., Kuusela, J., Melle, W., Mork, K. A., Wennevik, V., and Østborg, G. M. 2012. Age and fine-scale marine growth of Atlantic salmon post-smolts in the Northeast Atlantic. – ICES Journal of Marine Science, 69: 1668–1677. Surface trawls were conducted over a large area of the Northeast Atlantic in 2002, 2003, 2008, and 2009 to collect samples of Atlantic salmon (Salmo salar) post-smolts during their marine feeding migration (n = 2242). The dominant smolt age of wild post-smolts was 2 years, followed by 1- and 3-year-old fish, and a few 4-year-old fish. The average rate of circulus formation in the marine zone of scales was estimated to be 6.3 d circulus−1. Both the age structure and the number of marine circuli in the scales suggest that the majority of the post-smolts originated in rivers in southern Europe. Applying intercirculi distances in scales as a proxy variable of growth rate suggests that putative marine growth rates varied among years, with the fastest growth rates in 2002 and the slowest growth rates in 2008. Further, the first marine intercirculi distances were narrowest in 1-year-old smolts, successively increasing with smolt age, indicating that growth rates during the first period at sea were lowest for salmon of southernmost origin. Growth indices are linked to prevailing environmental and biological conditions.

Exploring the Transcriptome of Atlantic Salmon (Salmo salar) Skin, a Major Defense Organ

The skin of fish is the first line of defense against pathogens and parasites. The skin transcriptome of the Atlantic salmon is poorly characterized, and currently only 2,089 expressed sequence tags (ESTs) out of a total of half a million sequences are generated from skin-derived cDNA libraries. The primary aim of this study was to enhance the transcriptomic knowledge of salmon skin by using next-generation sequencing (NGS) technology, namely the Roche-454 platform. An equimolar mixture of high-quality RNA from skin and epidermal samples of salmon reared in either freshwater or seawater was used for 454-sequencing. This technique yielded over 600,000 reads, which were assembled into 34,696 isotigs using Newbler. Of these isotigs, 12% had not been sequenced in Atlantic salmon, hence representing previously unreported salmon mRNAs that can potentially be skin-specific. Many full-length genes have been acquired, representing numerous biological processes. Mucin proteins are the main structural component of mucus and we examined in greater detail the sequences we obtained for these genes. Several isotigs exhibited homology to mammalian mucins (MUC2, MUC5AC and MUC5B). Mucin mRNAs are generally >10kbp and contain large repetitive units, which pose a challenge towards full-length sequence discovery. To date, we have not unearthed any full-length salmon mucin genes with this dataset, but have both N- and C-terminal regions of a mucin type 5. This highlights the fact that, while NGS is indeed a formidable tool for sequence data mining of non-model species, it must be complemented with additional experimental and bioinformatic work to characterize some mRNA sequences with complex features.

Using Phylogenetic Analysis to Detect Market Substitution of Atlantic Salmon for Pacific Salmon: An Introductory Biology Laboratory Experiment

We describe a laboratory exercise developed for the cell and molecular biology quarter of a year-long majors’ undergraduate introductory biology sequence. In an analysis of salmon samples collected by students in their local stores and restaurants, DNA sequencing and phylogenetic analysis were used to detect market substitution of Atlantic salmon for Pacific salmon. This allowed students to apply molecular methods such as polymerase chain reaction (PCR) and DNA sequencing to a socially relevant issue.

Dynamics of body size, age, and annual growth rate of Anadyr chum salmon Oncorhynchus keta in 1962–2010

Interannual variability of body length, body weight, age structure, and seasonal growth rate of Anadyr chum salmon Oncorhynchus keta was studied using the monitoring data obtained in 1962–2010 in Anadyr River and Anadyr Firth. Body size of spawning adults has decreased significantly for the decade of 1990–2000s compared to the period of 1960–1970s, and the ratio of elder specimens was higher. Annual growth dynamics showed different patterns. Estimated from measuring intersclerite distances on scales, first-year growth of Anadyr chum salmon samples collected in 1962 to 2007 was enhanced. After the first year, growth was reduced. The greatest reduction occurred in the third and forth years. Analysis of seasonal growth of scale evidences to the relaxation of the growth rates of Anadyr chum salmon after the first year of life preconditioned by both the over-wintering and foraging period. These data are in contradiction with the wide-spread suggestion of decreasing of chum salmon body length during winter due to bad feeding conditions. According to the similarity of the dynamics of body length and growth rates of chum salmon and pink salmon O. gorbuscha observed for the last decades, we assume that this may be preconditioned by the same large-scale limiting factors that affect similarly these salmon species inhabiting vast areas. Our data do not support the idea about high-density population of chum salmon as a main factor affecting the productivity characteristics of this species in the northern Pacific Ocean in the second half of the 20th-beginning of the 21st century. Reasons for decrease of chum salmon body length are discussed.

Effect of charcoal types and grilling conditions on formation of heterocyclic aromatic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs) in grilled muscle foods

Grilling muscle foods involves high temperatures that lead to production of cooking toxicants, such as heterocyclic aromatic amines (HAs) and polycyclic aromatic hydrocarbons (PAHs). To obtain realistic exposure levels of these two groups of mutagens analyses of the same samples using similar separation/detection techniques were performed. HAs and PAHs were quantified in well-done meat and fish samples grilled with wood and coconut shell charcoal at 200°C. Quantitative HAs and PAHs profiles were different for beef and salmon using the same type of charcoal. Higher levels of HAs and PAHs were found in salmon samples. No significant differences were observed for HAs and PAHs in beef samples grilled with both charcoal types, whereas salmon grilled with coconut shell charcoal presented significantly lower amounts of HAs and PAHs than salmon grilled with usual wood charcoal. Continuous barbecuing with the same charcoal shown that combustion of fat that dropped along the grilling period contributed to higher formation of HAs and PAHs. Special attention must be given to the intake of barbecued foods since high amounts of HAs and PAHs can be taken in a single meal.

Polybrominated diphenyl ether levels in wild and farmed Chilean salmon and preliminary flow data for commercial transport

AbstractThis pilot study documented the occurrence and levels of brominated flame retardants in the tissues of farmed and wild salmon in southern Chile. Samples of Coho salmon and rainbow trout were obtained from fish farms, rivers and lakes in the Patagonia in Aysen Region, Chile. The samples were analyzed by Gas Chromatography Negative Chemical Ionization Mass Spectrometry for the different polybrominated diphenyl ether (PBDE) congeners. Contaminants were observed in all the samples, and the congeners BDE 17, 28, 47 and 66 were observed in all both farmed and wild samples. The concentrations were higher in the farmed Coho salmon, presenting significant differences with wild salmon. The levels reached 182 pg/g wet weight (ww) vs. 120 ww. In the case of the rainbow trout, the concentrations were lower, although the congener profile was quite similar. The levels reached an average of 100 pg/g ww in the farmed fish versus 110 pg/g ww in wild fish, and no significant difference was observed between the species. In both species, the congener with the highest concentration was BDE 47. Based on this information, the BDE flow was estimated for commerce, which is a form of pollutant transport not usually considered in POP pollution studies. A preliminary estimation indicated that the quantity of PBDEs mobilized by commerce was in the order of kg, and in the case of Chile might reach almost 1 kg.

Simultaneous determination of the residues of fourteen quinolones and fluoroquinolones in fish samples using liquid chromatography with photometric and fluorescence detection

A chromatographic method is described for assaying fourteen quinolones and fluoroquinolones (pipemidic acid, marbofloxacin, norfloxacin, ciprofloxacin, danofloxacin, lomefloxacin, enrofloxacin, sarafloxacin, difloxacin, oxolinic acid, nalidixic acid, flumequine, and pyromidic acid) in fish samples. The samples were extracted with m-phosphoric acid/acetonitrile mixture (75:25, v/v), purified, and preconcentrated on ENV + Isolute cartridges. The determination was achieved by liquid chromatography using C&lt;sub&gt;18&lt;/sub&gt; analytical column. A mobile phase composed of mixtures of methanol-acetonitrile-10mM citrate buffer at pH 4.5, delivered under optimum gradient program, at a flow rate of 1.5 ml/min, allows accomplishing the chromatographic separation in 26 minutes. For the detection were used serial UV-visible diode-array at 280 nm and 254 nm and fluorescence detection at excitation wavelength/emission wavelength: 280/450, 280/495, and 280/405 nm. The detection and quantification limits were between 0.2–9.5and 0.7–32 µg/kg, respectively. The procedure was applied to the analysis of spiked salmon samples at two different concentration levels (50 µg/k and 100 µg/kg). Mean recoveries of fluoroquinolones from the salmon samples ranged from 50% to 102%, depending on the analyte.

Microbiological quality of salmon (Salmo salar) sold in cities of the state of SãO Paulo, Brazil.

The present paper evaluated the microbiology of salmon by quantifying mesophilic heterotrophic microorganisms, total and thermotolerant coliforms, and the presence of Vibrio parahaemolyticus, Staphylococcus aureus, Salmonella sp., Escherichia coli and Aeromonas sp. in the meat. This study can provide technical support for the suggestion of a new regulation of a Brazilian legislation through specific microbiological standards concerning the consumption of raw fish. A number of 31 (16 cooled and 15 frozen) samples of salmon were collected in the retail market network of a few cities in the State of São Paulo, Brazil. Results presented populations of mesophilic heterotrophic microorganisms ranging from 1.0 × 10 and 3.9 × 106 CFU/g, total and thermotolerant coliforms in 32.25% and 19.35% of the samples, respectively, and Aeromonas sp. in 41.95% of the samples with a populational variation ranging from 2.0 × 102 to 8.0 × 103 CFU/g. Staphylococcus aureus was found in one sample whereas Vibrio parahaemolyticus, Salmonella sp. and Escherichia coli were not found. These results demonstrated the presence of potencially pathogenic microorganisms in fresh fish consumed in Brazil, highlighting the necessity of control measures to avoid public health problems related to the consumption of raw fish.

Effects of edible coatings based on ultrasound-treated whey proteins in quality attributes of frozen Atlantic salmon (Salmo salar)

Abstract The effects of ultrasound-treated whey protein coatings on frozen Atlantic salmon quality parameters were evaluated. The experiment was performed using an ultrasonic bath at a frequency of 35 kHz and three sonication times (1, 15 and 60 min). The yield, the thaw yield, the drip loss in thawing, the drip loss after chilled storage and the cooking loss of fish samples were not influenced by the ultrasound treatment of coatings when compared to fish samples with untreated whey protein coatings. Decreases in yield, drip loss in thawing and drip loss after chilled storage were observed in samples from whey proteins sonicated 60 min in relation to those sonicated 15 min. The ultrasound treatment of whey proteins did not modify the colour of frozen and thawed fillets but increased L* and whiteness of cooked samples in comparison with untreated whey protein coated samples. All whey protein coatings decreased the lipid oxidation of fish fillets. However, the ultrasound treatment of coatings significantly delayed the lipid oxidation of salmon pieces in comparison with those coated with untreated proteins. The sensory properties of salmon samples were not negatively affected by these coatings. Industrial relevance Freezing is a very usual method of fish preservation; some changes during frozen storage that decrease product quality can occur, such as lipid oxidation. The results obtained in this investigation show that ultrasound applied to whey protein coatings could be useful for the reduction of the lipid oxidation of frozen salmon. These treated coatings could be a good alternative to conventional packaging and, at least, they could partially substitute plastic packaging. The edible coatings can contribute to reduce the plastic packaging residues of frozen seafood industry and the environmental contamination.

Marketplace substitution of Atlantic salmon for Pacific salmon in Washington State detected by DNA barcoding

Accurate identification of seafood in the marketplace is an issue of international concern, due to high rates of market substitution of cheaper or more widely available species for expensive or high-demand species. Salmon samples from stores and restaurants throughout western Washington, USA were tested using DNA sequencing of a short section of the mitochondrial cytochrome c oxidase I (COI) gene (DNA barcoding) to identify Atlantic salmon substituted for Pacific salmon. Of 99 salmon samples, 11 (11%) were Atlantic salmon sold as Pacific salmon. More than 38% of restaurant samples were mislabeled to species, while only 7% of store samples were mislabeled. Market substitution rates were significantly greater in restaurants compared to stores, and consistently greater in winter compared to spring, although not significantly. The high market substitution rate in restaurants documents a pressing need for more monitoring and enforcement specifically in restaurants. DNA barcoding is a valuable tool for rapid and definitive authentication of salmon in the marketplace, and should be more widely adopted to discourage market substitution.

Analysis of incurred crystal violet in Atlantic salmon (Salmo salar L.): comparison between the analysis of crystal violet as an individual parent and leucocrystal violet and as total crystal violet after oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone

Due to on-going concern about the occurrence of triphenylmethane dye residues in fish destined for human consumption, a depletion study of crystal violet in salmon was carried out. Atlantic salmon less than 12 months old were exposed to crystal violet in fresh water at 15°C and subsequently sampled at 1, 7, 14, 28, 63 and 91 days after exposure. The salmon were then analysed by two analytical methods. In the first method, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) was used to oxidise leucocrystal violet to its parent form. Total parent crystal violet was then analysed by LC-MS/MS. In the second method, crystal violet and leucocrystal violet were analysed individually by LC-MS/MS without oxidation. Both methods gave comparable results for total crystal violet concentrations, with a correlation of r 2 = 0.69. Statistical treatment for 88 incurred salmon samples showed no significant difference between the two sets of results with t = 1.68 and t crit = 1.99. Up to 98% of crystal violet was metabolised to its leuco form in the salmon after 1 day of exposure and could be detected at significant concentrations (approximately 20 µg kg–1) 91 days after exposure. The depletion data also suggest that crystal violet has a half-life of approximately 15–16 days in salmon.

Viability of Listeria monocytogenes in an experimental model of nigiri sushi of halibut (Hippoglossus hippoglossus) and salmon (Salmo salar)

Sushi is a traditional Japanese food, mostly consisting of raw seafood in combination with rice. However, eating sushi has become popular among consumers in many countries outside Japan. Sushi is not free from health risks and foodborne illness linked to this product has been caused by Listeria monocytogenes. The aim of our work was to study viability of L. monocytogenes in emulated nigiri sushi comprised of halibut and salmon. Raw samples of halibut and salmon were inoculated with the pathogen and subsequently put on top of vinegar marinated sushi rice followed by storage for 7 days at 4 and 8 °C. As controls, inoculated seafood without rice was used. The experiments demonstrated that the level of L. monocytogenes in nigiri sushi was significant lower during storage over 7 days at 4 and 8 °C compared to controls, in case of inoculated seafood only. The pH drop in the fish muscle, caused by the sushi rice, is believed to be the reason for the decrease in viability of L. monocytogenes in nigiri sushi.

Mercury Concentrations in Fish Jerky Snack Food: Marlin, Ahi, and Salmon

BackgroundDried meat and fish have served as an important durable nutrition source for humans for centuries. Because omega 3 fatty acids in fish are recognized as having antioxidant and anti inflammatory properties found to be beneficial for good health, many consumers are looking to fish as their main source of protein. Unfortunately, contaminants such as methylmercury can accumulate in some species of fish. The purpose of this research is to test commercially available fish jerky snack foods for mercury contamination.MethodsFifteen bags of marlin jerky, three bags of ahi jerky, and three bags of salmon jerky were purchased from large retail stores in Hawaii and California, and directly from the proprietors' Internet websites. Five individual strips of jerky per bag were analyzed for a total of one hundred and five tests.ResultsFrom the seventy-five marlin jerky samples, mercury concentration ranged from 0.052-28.17 μg/g, with an average of 5.53 μg/g, median 4.1 μg/g. Fifty-six (75%) marlin samples had mercury concentrations that exceeded the FDA's current mercury action level of 1.0 μg/g, while six samples had greater than 10 μg/g. Fifteen samples of ahi had mercury concentrations ranging from 0.09-0.55 μg/g, while mercury concentrations in fifteen salmon samples ranged from 0.030-0.17 μg/g.ConclusionsThis study found that mercury concentrations in some fish jerky can often exceed the FDA's allowable mercury limit and could be a significant source of mercury exposure.

Prevalence and antimicrobial susceptibility of major foodborne pathogens in imported seafood.

Seafood is a leading commodity implicated in foodborne disease outbreaks in the United States. Seafood importation rose dramatically in the past 3 decades and now contributes to more than 80% of the total U.S. seafood supply. However, limited data are available on the microbiological safety of imported seafood. In this study, we obtained a total of 171 salmon, shrimp, and tilapia samples imported from 12 countries in three retail stores in Baton Rouge, LA. The total microbial population and the prevalence and antimicrobial susceptibilities of six major foodborne-pathogen genera (Campylobacter, Escherichia coli, Listeria, Salmonella, Shigella, and Vibrio) were determined. The aerobic plate counts (APC) for the 171 samples averaged 4.96 log CFU/g, with samples from Chile carrying the highest mean APC of 6.53 log CFU/g and fresh samples having a significantly higher mean APC than frozen ones (P < 0.0001). There were 27 samples (15.8%) with unacceptable microbiological quality (APC > 7 log CFU/g). By culture, no sample tested positive for Campylobacter coli, Shigella, or Vibrio vulnificus. Campylobacter jejuni and Salmonella enterica serovar Typhimurium were each recovered once from farm-raised tilapia from China. By PCR, 17.5 and 32.2% of the samples were positive for Salmonella and Shigella, respectively. The overall prevalence rates of other target bacteria were low, ranging from 4.1% for Listeria monocytogenes to 9.4% for E. coli. All of the Vibrio parahaemolyticus isolates recovered were from shrimp, and 63.3% showed intermediate resistance to ampicillin. Both C. jejuni isolates possessed a rare resistance to gentamicin, while 75% of L. monocytogenes isolates were resistant to nitrofurantoin. Taken together, these findings suggest potential food safety hazards associated with imported seafood and warrant further large-scale studies.

Single‐Nucleotide Polymorphism (SNP) Loci Correlated with Run Timing in Adult Chinook Salmon from the Columbia River Basin

AbstractRun timing in Chinook salmon Oncorhynchus tshawytscha is a life history trait that varies among populations throughout the Columbia River basin and has a demonstrated genetic basis. In this study, we used 92 single‐nucleotide polymorphic (SNP) markers linked to at least 75 different functional genes (including OtsClock1a) to test for correlations with run timing. We obtained samples of adult Chinook salmon on a weekly basis as they passed a fixed point (Bonneville Dam) on the lower Columbia River main stem during the majority of the migratory run from April to October for three sequential years from 2007 to 2009 (n = 2,731, 3,479, and 2,960, respectively). Since these fish represented unknown mixtures of the three major genetic lineages in the Columbia River basin, we used genetic stock identification to assign individuals to their likely stock of origin. We then determined whether allelic variation at the SNP loci was correlated with the date of passage of fish in the context of stock of origin. Nine SNP loci were identified as candidates based on significant correlations with date of passage using the spatial analysis method. A multivariate analysis was then used to rank these eight candidate loci according to the proportion of genetic variation that day of passage explained relative to two other predictor variables: population structure and temperature. The three top‐ranked loci were Ots_TAPBP, Ots_97077–179R, and Ots_myoD‐364, which have known involvement in immunological functioning and muscle differentiation. Future work will test candidate SNPs using run‐timing information from fish of known origin within particular Columbia River subbasins to help validate the role of these genetic linkage groups in this important life history trait.

Antibacterial activity of egg yolk antibody (IgY) against Listeria monocytogenes and preliminary evaluation of its potential for food preservation

Egg yolk antibody (IgY) is a unique type of immunoglobulin found in egg yolks, and many reports have described its ability to inhibit corresponding antigen bacteria. The objective of this study was to evaluate the antibacterial activity of IgY specific to Listeria monocytogenes, an important food pathogen to both humans and animals, as well as its potential use for food preservation. Specific IgY was generated by immunising Leghorn chickens with whole cells of L. monocytogenes, and its inhibitory effect on bacterial growth was tested in liquid medium and food samples. After 8 h of incubation with specific IgY, there was a significant decrease in the growth (absorbance at 600 nm) of L. monocytogenes in comparison with controls. IgY also inhibited the growth of L. monocytogenes inoculated onto fresh or smoked salmon samples. Compared with those of blanks, numbers of L. monocytogenes were reduced by more than 2 log units after 15 days of storage at 6 ± 1 °C in the presence of specific IgY. The results suggest the potential application of specific IgY as a natural antimicrobial agent for food preservation.

Comparison and evaluation of Renibacterium salmoninarum quantitative PCR diagnostic assays using field samples of Chinook and coho salmon

Renibacterium salmoninarum is a Gram-positive bacterium causing bacterial kidney disease (BKD) in susceptible salmonid fishes. Several quantitative PCR (qPCR) assays to measure R. salmoninarum infection intensity have been reported, but comparison and evaluation of these assays has been limited. Here, we compared 3 qPCR primer/probe sets for detection of R. salmoninarum in field samples of naturally exposed Chinook and coho salmon first identified as positive by nested PCR (nPCR). Additional samples from a hatchery population of Chinook salmon with BKD were included to serve as strong positive controls. The 3 qPCR assays targeted either the multiple copy major soluble antigen (msa) genes or the single copy abc gene. The msa/non-fluorescent quencher (NFQ) assay amplified R. salmoninarum DNA in 53.2% of the nPCR positive samples, whereas the abc/NFQ assay amplified 21.8% of the samples and the abc/TAMRA assay 18.2%. The enzyme-linked immunosorbent assay (ELISA) successfully quantified only 16.4% of the nPCR positive samples. Although the msa/NFQ assay amplified a greater proportion of nPCR positive samples, the abc/NFQ assay better amplified those samples with medium and high ELISA values. A comparison of the geometric mean quantity ratios highlighted limitations of the assays, and the abc/NFQ assay strongly amplified some samples that were negative in other tests, in contrast to its performance among the sample group as a whole. These data demonstrate that both the msa/NFQ and abc/NFQ qPCR assays are specific and effective at higher infection levels and outperform the ELISA. However, most pathogen studies will continue to require multiple assays to both detect and quantify R. salmoninarum infection.

Development of a low-cost non-destructive system for measuring moisture and salt content in smoked fish products

In this study, a new method to assess salt content in smoked fish products using impedance spectroscopy has been developed. Two fish species (salmon and cod) from two different brands were analyzed. The analyses carried out were moisture, lipid, and salt contents, as well as aw. Impedance measurements were performed directly in different locations on smoked product by using a coaxial needle. The modulus and phase of the spectra of impedance were acquired between 1Hz and 1MHz, for 50 values of frequency. The impedance modulus and phase values were used to predict the studied physico-chemical parameters, by using the PLS method. In general, the highest lipid contents and the lowest moisture values were observed in salmon samples, independently of the brand and the batch analyzed. The results showed a high variability between batches of a same product, regarding to moisture and salt content. Prediction models were established for all the samples studied and also individually for each product. A higher accuracy of prediction was obtained for the PLS models established for each product compared with the model applied for all samples. In general, the highest R2 was obtained for prediction of aw parameter, followed by moisture content. The best correlations were obtained for smoked cod samples independently of the brand. These results can be explained by the isolating effect of the fat. Due to the differences in the raw material composition, a single model cannot be applied for all the products. A previous characterization of the raw material would improve the accuracy of the developed methodology. These results show the feasibility of the impedance spectroscopy to determine salt and moisture contents.