Fish Slices Research Articles

Insight into the mechanism on nano fish bone improving the quality of marinated snakehead fish slices during freeze-thaw cycles

The effects of marinating with nano fish bone (NFB) on the physicochemical characteristics and quality of snakehead fish slices during freeze-thaw cycles (1, 3, 5, 7, and 9) were investigated. The highest alterations in surface hydrophobicity, carbonyl content and secondary structure of the slice myofibrillar protein, integrity of cellular structure, and slice quality (whiteness, thawing loss, cooking loss, and sensory) were found in the sample without cryoprotectant (Ck), followed by the sample with commercial cryoprotectant of polyphosphates (PPS), and the lowest in the NFB sample. Comparatively, more moisture but less free water was observed in the NFB sample during the freeze-thaw cycles. Furthermore, NFB surrounded the oil droplet to form a Pickering emulsion, resulting in the stabilization of oil in the marinade. The results indicated that NFB can serve as a potential alternative to commercial cryoprotectant in frozen fish slices, which is attributed to its antifreeze and antioxidant functionalities.

A fish market survey using a novel PCR-sequencing-based protocols for the identification of commercial significant fish species

This study developed a simple, specific, and affordable PCR-sequencing-COI gene-based protocol for the simultaneous identification of some important commercial fish species: Merluccius merluccius, Lates niloticus, Gadus morhua, Ruvettus pretiosus, Pangasianodon hypophthalmus, Epinephelus spp. For this study, a local market survey on fish was carried out to evaluate the application of labelling laws and to detect fraudulent actions using the developed PCR protocols. Ten specimens of each fish species of interest were obtained from wholesale fishery plants and were utilized for the protocol development. DNA was extracted from the individual samples and quantified. DNA isolates were subjected to end-point PCR and the PCR products were sequenced. For the identification of fish species, novel species-specific primers were developed by the program "Primer Express 3.0" and by the software “Primer-BLAST” to amplify fragments of 200 bp, 250 bp, 300 and 562 bp, 350 bp, 400 bp and 522 bp within the COI gene for M. merluccius, L. niloticus, G. morhua, R. pretiosus, P. hypophthalmus, Epinephelus spp., respectively. Single PCR was performed using DNA isolates and developed primers for each fish species of interest. After sequencing, the isolates were compared with the selected sequences of the COI gene and showed a similarity ranging from 99 to 100%. Among 43 samples obtained for the survey, 19 (44.2%) were mislabelled, with 18 (41.9%) mislabelled samples from local fisheries and fish marketplaces and 1 (2.32%) from hypermarket stores. Among fish samples purchased at local fisheries and fish marketplaces, fraudulent actions were observed more frequently in fish slices (100%) than fish fillets (65%). Regarding fish fillets, out of four samples labelled as grouper, three were L. niloticus and one P. hypophthalmus. Two fillets marketed as cod were substituted with L. niloticus. Five samples labelled as “fillet” and two samples labelled as “perch” were identified as P. hypophthalmus. Regarding fish slices, all samples marketed as grouper (E. marginatus) were slices of R. pretiosus. The single case of mislabelling detected from fishery products purchased at hypermarket stores was a sample of “Spinycheek grouper” (Epinephelus diacanthus) that was indicated on label as “Grouper” (Epinephelus marginatus). In summary, our work highlights the need for continuous surveillance of the commercialization of fishery products, to reduce the number of fraud cases that happen in the market. Furthermore, our protocols based on PCR techniques could be useful for quality control of fresh finfish and to strengthen controls on the most frequent fraudulent actions of marketed fishery products.

Technology Development of Immediately Fished Cuttings for Restaurants

The topicality. The current state of nutrition of Ukraine population is analyzed in the article, draws conclusions about the possible improvement of the situation by creating products from fish raw materials with the addition of functional food ingredients of plant origin, which will have improved organoleptic characteristics and increased energy and nutritional value, as well as recommended as a functional product in the diet of certain categories of the population. Purpose and methods. The purpose of the study is to substantiate the recipe of a new type of fish semi-finished products “Zrazy fish slices chopped with poppy and sesame seeds” with enrichment with their functional ingredients. The object of research is the technology of the semi-finished product “Zrazy fish cut with poppy and sesame seeds”. The subject of the study are semi-finished products “Zrazy fish slices”, semi-finished products “Zrazy fish slices with poppy seeds and sesame seeds”, Atlantic mackerel fillets (DSTU 4378: 2006), sesame seeds (DSTU 7012: 2009) and poppy seeds (DSTU 7696: 2015). Research methods: the research was based on methods of theoretical generalization, comparative analysis, and calculation, organoleptic. Results. The results of theoretical and experimental research of creation of technology of fish semi-finished product “Zrazy fish cut with poppy and sesame seeds” of functional purpose have been shown. The chemical composition of the main raw material of the dish – Atlantic mackerel has been analyzed and its advantages in the recipe composition have been proved. Possibility of using poppy seeds and sesame seeds as functional ingredients in the dish has been confirmed. The organoleptic parameters of the dish were studied and the optimal ratio of poppy seeds and sesame seeds in breadcrumbs has been determined. The nutritional, energy value and vitamin-mineral composition of the dish “Fish slices chopped with poppy and sesame seeds” have been calculated. Conclusions and discussions. The traditional recipe of the dish “Zrazy fish cut” has been analyzed. The expediency of modification of the traditional recipe due to the complete replacement of the main fish raw material with Atlantic mackerel fillet and the functional ingredients introduction of plant origin, namely poppy seeds and sesame seeds in breadcrumbs zrazy has been proved. The optimal content of poppy seeds and sesame seeds has been determined in the recipe of the dish “Fish cut with poppy seeds and sesame seeds”, which is 1.2% of poppy seeds and 0.6% of sesame seeds in breadcrumbs. It has been found that the variant of the recipe № 3 dishes “Zrazy fish slices cut with poppy and sesame seeds” has the best organoleptic quality indicators: harmonious taste properties, and due to the introduction of breading poppy and sesame seeds acquire an attractive and original appearance. It has been proved that the introduction of Atlantic mackerel fish fillets, poppy seeds and sesame seeds into the recipe composition allows to significantly increase the content of fats (5 times chopped fish with poppy seeds and sesame seeds) in fats (5 times), unsaturated fatty acids (4.5 times) , PUFA (6.9 times). The content of such minerals as calcium, magnesium, iron, and vitamins B2, B3, B6, PP, K, D in the dish increased by more than 50%. The latest recipe “Fish cut with poppy and sesame seeds” ensures the absorption of calcium in full due to the presence in its chemical composition of the optimal ratio of Ca: P: Mg = 1: 1,48: 0,5. The energy value of the dish has increased almost 1.5 times. The degree of daily nutrient requirements for men of the III working age group aged 30 to 39 years of the dish “Fish cut with poppy and sesame seeds” in such as dietary fiber (13.05%), PUFA (36.6%), calcium (12.99%), magnesium (18.88%), phosphorus (19.23%), vitamin D (258.4%).

Ethanolic Noni (Morinda citrifolia L.) leaf extract dechlorophyllised using sedimentation process: Antioxidant, antibacterial properties and efficacy in extending the shelf‐life of striped catfish slices

SummaryAntioxidant and antimicrobial activities of ethanolic noni leaf extract (ENLE) without and with chlorophyll removal by sedimentation method were comparatively investigated. Total chlorophyll content was reduced by 82% in the top fraction (CR‐ENLE) collected after 24 h at 4 °C as compared to that of ENLE. Antioxidant and antimicrobial activities were lower in the bottom fraction rich in chlorophyll (Chlo‐ENLE) than others (P < 0.05). Based on the microbiological limit, the shelf‐life of striped catfish slices pre‐treated with 400 mg kg−1 C‐R‐ENLE was extended to 9 days as compared to the 3 days recorded for the control (without pre‐treatment). Slices treated with CR‐ENLE had lower lipid oxidation than those treated with ENLE during refrigerated storage (P < 0.05). The sedimentation process was therefore a potential green method for producing ENLE having improved antioxidant and antimicrobial activities without green colour. It can be used as a natural additive for shelf‐life extension of fish slices.

Big Data Security Based Framework Using Metaheuristic Approaches in Cloud Environment

Security is the main concern in Big Data analysis. In the security analysis, most of the approaches that provide an effective security yet uses high amount of resources like memory or storage and time delay in order to increase the cost of processing. This paper emphasis on improvement based on utilization of resources by means of optimization of encryption approach. The optimisation approach uses a convex optimization with minimum amount of time or storage and such factors effects the total cost of processing. The proposed approach uses GWO optimization of Blow fish slices. The experiment involves the use of two types of dataset such as tweet and scientific workflow. The exper- imental analysis shows how effectively blow fish improves Grey wolf optimization (GWO). In addition, the other experiment uses particle swarm optimization (PSO) and flower pollination approach (FPA). Although the analysis represents that these approaches are not very much effective as compared to GWO.

Growth Kinetics and Spoilage Potential of Co-culturing Acinetobacter johnsonii and Pseudomonas fluorescens from Bigeye Tuna (Thunnus obesus) During Refrigerated Storage.

A. johnsonii and P. fluorescens are the well-known specific spoilage organisms in aquatic products and the study of the interactions between A. johnsonii and P. fluorescens are limited. This study aims to evaluate the growth kinetics, spoilage potential and interactions ofA.johnsonii andP. fluorescens isolated from spoiled bigeye tuna (Thunnus obesus) by inoculating into sterile fish slices and stored at 4°C for 6days. The growth kinetics of A. johnsonii and P. fluorescens were fitted with Baranyi and Roberts model. The chemical indexes (total volatile base nitrogen (TVB-N), trimethylamine (TMA), pH, proteolytic activity and protein content) of each inoculated block of bigeye tuna were increased during refrigerated storage. Moreover, the higher contents of chemical indexes were observed in co-culture with A. johnsonii and P. fluorescens compared with single culture of A. johnsonii and P. fluorescens. In addition, atomic force microscopy (AFM) observation of co-culturing A. johnsonii and P. fluorescens inoculation into sterile fish slices revealed damage of myofibrillar protein structures and the protein degradation. Based on these parameters, a rapid method to evaluate spoilage potential of A. johnsonii and P. fluorescens was positively correlated with TVB-N value, TMA value and pH value (P < 0.05) by the correlation coefficient. Consequently, spoilage potential of microorganisms became stronger evaluated in a mixed culture than single culture. This paper provides insight for a detection method of interactions of A. johnsonii and P. fluorescens during refrigerated storage.

The combined effect of squid pen chitooligosaccharides and high voltage cold atmospheric plasma on the shelf-life extension of Asian sea bass slices stored at 4 °C

Combined effects of high voltage cold atmospheric plasma (HV-CAP) generated with the mixture of argon and oxygen (90%Ar/10%O2) for 5 min and chitooligosaccharide (COS) from squid (Loligo formosana) pen (internalized shell) at different concentrations (0.05, 0.1 and 0.2 g/100 g fish slices) on the shelf-life of Asian sea bass (ASB) slices were investigated during storage at 4 °C for 18 days. Total viable count (TVC) of fish slices treated with 0.1 or 0.2 g/100 g COS in conjunction with HV-CAP was lower than the acceptable limit (log 106 CFU/g sample) within 18 days. The growth of various pathogenic and spoilage bacteria including psychrophilic bacteria, Clostridium perfringens (not detected), lactic acid bacteria (3.77–4.37 log CFU/g), Enterobacteriaceae (4.03–4.50 log CFU/g), Pseudomonas (6.62–6.82 log CFU/g) and hydrogen sulphide (H2S)-producing (4.04–5.05 log CFU/g) bacteria of HV-CAP-treated slices containing COS was more inhibited than other treatments, especially during the first 15 days of storage. The thiobarbituric acid reactive substances (TBARS) and peroxide values (PV) of slices treated with combined HV-CAP and COS (0.1 or 0.2 g/100 g) were reduced by 28‐–64 and 40–46%, respectively than those treated with only HV-CAP throughout the storage (p <.05). Similarly, for HV-CAP treated slices, addition of COS decreased the total carbonyl content by 15–24% than those added without COS. COS was able to lower the oxidation of polyunsaturated fatty acids of slices caused by HV-CAP. Therefore, HV-CAP together with COS effectively prolonged the shelf-life of ASB slices with sensory acceptability at 4 °C for at least 12 days.

Properties and application of bilayer films based on poly (lactic acid) and fish gelatin containing epigallocatechin gallate fabricated by thermo-compression molding

An alternative approach towards production of active bilayer films based on poly (lactic acid) (PLA) and fish gelatin incorporated with epigallocatechin gallate (EGCG) fabricated by thermo-compression molding was investigated. This strategy permitted the reduction of production times and avoided the uses of inorganic solvents. Thermo-compression molded bilayer films showed good handling, transparency and low water vapor permeability. The incorporation of EGCG promoted interactions with gelatin, as shown by Fourier transform infrared spectroscopy. These interactions contributed to homogeneous structures, as observed by scanning electron microscopy. Bilayer films with 12 wt % EGCG showed good mechanical properties, high water and UV–visible light barrier properties as well as a high DPPH radical scavenging activity. These bilayer films were used to produce bags, in which striped catfish slices (SCS) were packaged. After 7 days of storage at 4 °C, SCS packaged in bags prepared with12 wt % EGCG had lower psychrophilic bacteria count, weight loss, peroxide value, and thiobarbituric acid reactive substances (TBARS) value along with higher docosahexaenoic acid (C22:6 n-3) content than those packaged in bags prepared without EGCG or in LLDPE bags. No difference in overall likeness score was found among all the samples packaged in different bags after 7 days of storage. Therefore, PLA/gelatin bilayer films containing 12 wt % EGCG possessed satisfactory film properties with augmented antioxidant activity, and thus they could be used as active food packaging, especially for fish slices with high lipid content.

Gelatin Based Edible Coating: Preservation Technique for Seer (Scomberomorus guttatus) Fish Slices

The aim of this work is to examine the performance of gelatin based edible coating in preserving the seer fish slices. A composite edible coating solution was prepared with three different concentrations of gelatin, chitosan and vinegar. Coating experiments were performed in a laboratory scale edible coating tank which was fabricated for this purpose. The seer fish slices (13.65±2.50 mm thick and 43.89± 6.82 g weight) were subjected to coating for three different soaking times (min). While coating performance of the solution was assessed through coating uptake (%), texture quality of the seer fish slices was assessed through weight loss (%) and microbial quality was assessed through Total Plate Count (CFU/g). Experiment was designed using Box - Behnken Design (BBD). The application of edible coating treatment to seer fish slices resulted in improvement of overall keeping quality of the seer fish slices (9 days) against the control (3 days) when stored under low temperature (7±1oC).

Modeling the effect of pre-treatment with nisin enriched osmotic solution on the shelf life of chilled vacuum packed tuna

The objective of this study was the kinetic modeling of the effect of storage temperature on the quality and shelf life of chilled tuna, vacuum packed and osmotically pre-treated with the addition of nisin as antimicrobial agent. Tuna fillets were treated at 15 °C in osmotic solution with 50% high dextrose equivalent maltodextrin (DE 47) plus 5% NaCl, for 0–360 min. Untreated and 30 min osmotically pre-treated fish slices with and without nisin (2·104 IU/100 g osmotic solution), vacuum packed and stored at controlled isothermal conditions (0–15 °C) were studied. Quality assessment and modeling was based on microbial growth, total volatile basic nitrogen (TVB-N), trimethylamine nitrogen (TMA-N), lipid oxidation (TBARS) and sensory scoring.The water activity decreased to 0.96 at 30 min of pre-treatment. Osmotic pre-treatment led to significant shelf life extension of fish, in terms of microbial growth and sensory quality. The addition of nisin in the osmotic solution further increased the shelf life of tuna. Based on LAB growth, the shelf life was 10 days for untreated and 27 days for osmotically treated vacuum packed fish at 5 °C. The addition of nisin increased shelf life to 51 days at 5 °C.

Effect of storage temperature and osmotic pre-treatment with alternative solutes on the shelf-life of gilthead seabream (Sparus aurata) fillets

The objective of the study was the kinetic modelling of the shelf-life of osmotically pre-treated fish during refrigerated and super-chilled storage. Fresh gilthead seabream (Sparus aurata) fillets were treated for 0–360 min at 15 °C in osmotic solutions 50:5 high dextrose equivalent maltodextrin:NaCl/100 g (HDM), 40:10:5 HDM:trehalose:NaCl/100 g (HDM + treh) and 40:10:5 HDM:glucosamine:NaCl/100 g (HDM + gluc). Water loss, solid gain, salt content and water activity were monitored throughout treatment. Slices untreated and osmotically pre-treated for 45 min were aerobically packed and stored isothermally at 15, 10, 5, 2.5, 0, −1 and −3 °C. Quality assessment was based on microbial growth (total viable count, Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae spp., H2S-producing bacteria, lactic acid bacteria, yeasts and moulds), total volatile nitrogen (TVB-N), lipid oxidation (TBARs) and sensory scoring. Quality indices were kinetically modelled and temperature dependence of quality loss rates was modelled by Ratkowsky equation.Osmotic pre-treatment led to significant shelf-life extension of fillets, in terms of microbial growth, chemical changes and organoleptic deterioration. The pre-treatment with the alternative solutes led to depression of the freezing point (−1.8, −2.6, −3.2 and −3.5 °C for the untreated samples and the osmotically pre-treated with HDM, HDM + treh and HDM + gluc, respectively). TVB-N values were higher in untreated samples, followed by osmotically treated fillets, mainly at higher storage temperatures (i.e. 10 and 15 °C). Based on the mathematical models for sensory evaluation scoring, the shelf-life was 12, 19, 22 and 22 days at 0 °C for untreated and osmotically pre-treated with HDM, HDM + treh and HDM + gluc fish slices, respectively, while the respective values at −3 °C were 21, 35, 38 and 38 days. The alternative solutes had no significant effect on the quality and shelf-life of pre-treated fish fillet during storage at refrigerated conditions.

Effect of storage period before reheating on the volatile compound composition and lipid oxidation of steamed meat of yellowtail Seriola quinqueradiata

The effect of storage period before reheating on the volatile composition and lipid oxidation of steamed yellowtail fish muscle samples [ordinary muscle (OM) and dark muscle (DM)] was studied to evaluate the quality of fish meat in the cook-chill process. In OM and DM samples that were reheated on day 7 of storage, the levels of 26 compounds and most volatiles (47), respectively, were significantly higher than in samples that were steamed only once. In DM steamed only once and in DM reheated after 7 days of storage, values of nine and 32 compounds, respectively, were significantly higher than in OM under identical conditions. In both muscle types, the peroxide values (PVs) and thiobarbituric acid-reactive substances (TBARS) values significantly increased when the meat was stored for 7 days before reheating. Reheated DM showed significantly lower values and significantly lower tendency for PV except for day 1 of storage and significantly higher TBARS values at day 7 of storage compared to those in reheated OM. In reheated muscle of both types, the fatty acid composition was not significantly different from that of samples steamed only once, except for 20:5n-3 of DM. Sensory evaluation showed that at days 3 and 7 of storage, the odor of reheated fish slices had deteriorated. Therefore, steamed yellowtail meat reheated after refrigerated storage of up to 3 days could be consumed without deterioration of its odor and nutritive value.

Effect of drying methods and antioxidants on the flavor and lipid oxidation of silver carp slices

Silver carp slices were dried using hot air, microwave, and microwave-vacuum (MV). The drying kinetics, lipid oxidation, flavor, and content of fat, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and earthy-musty off-odour compounds were compared among the dried slices. Furthermore, the effect of vitamin C (Vc) and tea polyphenols (TP) on the microwave-dried fish slices was investigated. The Exponential models gave good fit for the drying data. Compared with hot air drying, microwave and MV drying reduced the drying time drastically. Drying removed part of the fishy off-odour, produced grilled flavor and “Oxidated oil” off-odour. Hot air dried fish slices had better grilled flavor. The TP restrict the formation of fishy and “Oxidated oil” off-odours effectively. Microwave drying removed a large part of “Earthy-musty” off-odour, and marinating with Vc or TP help to remove this off-odour. The slices dried with microwave or MV had less thiobarbituric acid reactive substance (TBARS). The TBARS decreased with power intensity during microwave drying but increased with the vacuum during MV drying. All drying processes largely decreased the contents of fat, EPA and DHA (P < 0.05). Microwave drying retained more fat (P < 0.05). The Vc and TP protected the EPA and DHA effectively.

Effect of Antioxidants on the Lipid Oxidation and Flavor of Microwave-assistant Dried Silver Carp (Hypophthalmichthys molitrix) Slices

&lt;p&gt;Silver carp slices were dried using microwave, and the effect of vitamin C (VC) and tea polyphenols (TP) on the quality of the dried fish slices were evaluated. The lipid oxidation, flavor, and content of fat, eicosapentaenoic (EPA), docosahexaenoic acid (DHA), earthy-musty off-odor compounds were compared among the dried slices. Marinating with VC and TP significantly protected the lipid from oxidation. Samples treated with TP (0.2 g/100 mL) retained the most of DHA and EPA, while restricting fishy off-odors. About 50% of geosmin and 70% of 2-methylisoborneol, the earthy-musty off-odor compounds, were removed by marinating with VC (0.4 g/100 mL) combined with microwave drying.&lt;/p&gt;

Influence of Smoking on Indicatory Congeners Residues Levels in Fish Slices

The aim of this study was do determine changes in concentrations of indicatory PCB congeners (IUPAC numbers: 28, 52, 101, 118, 153, 138, 180) during industrial hot smoking of mackerel (Scomber scombrus L.) and herring (Clupea harengus L.) slices and cold smoking of mackerel slices. PCB content in raw mackerel slices averaged from 1.32±0.29 ng/g wet w. for PCB 52 to 4.66±0.72 ng/g wet w. for PCB 153. In herring slices, PCB content ranged from 1.36±0.25 ng/g wet w. for PCB 28 to 16.50±1.94 ng/g wet w. for PCB 153. During hot smoking, losses of the examined compounds were observed - in herring slices by 15% (PCB 153) to 32% (PCB 52), while in mackerel slices by 3.7% (PCB 80) to 38% (PCB 28). Simultaneously, a slight increase in the content of PCB 180, PCB 118, PCB 153, PCB 138 and PCB 101 occurred during the proper smoking, between 1.5ᵗʰ and 2.5ᵗʰ hour of the smoking process. During cold smoking (26°C, 8 h), PCB concentrations increased significantly (p<0.05) by 26% (PCB 28, PCB 138) to 43% (PCB 180). In the final stage of smoking, PCB content in the alder sawdust and in the smoke had a significant effect on the levels of the analysed PCB congeners in the smoked slices. The main parameter determining the change of these compounds contents was their decrease in co-distillation with steam. In the final phase of the hot smoking a little increase of PCB compounds contents was a consequence of their penetration with smoke to the fish meat tissue.

Quality Changes of Dehydrated Restructured Fish Product from Silver Carp (Hypophthalmichthys molitrix) as Affected by Drying Methods

Restructured fish slices from silver carp (Hypophthalmichthys molitrix) were dried using air drying (AD), freeze drying (FD), and vacuum drying (VD) (4 mm thickness) and microwave-vacuum drying (MVD) (2, 4, 6, and 8 mm thickness). Quality attributes of the dried products were compared in terms of their rehydrated characteristics, change in dimensions, color, texture, sensory values before and after rehydration, and change in volatile compounds. AD, FD, and VD resulted in the different levels of shrinkage while MVD caused some expansion in diameter and thickness in the 4-, 6-, and 8-mm-thickness samples. Rehydration caused significant swelling in AD, FD, and VD products (p 0.05). Drying methods significantly affected the color and texture of both dried and rehydrated products (p 0.05). MVD products rehydrated faster and had higher rehydration ratio as well as lower water hold capacity, hardness, springiness, cohesiveness, and chewiness than others. In sensory evaluation, MVD products alone exhibited acceptable crispness and favorable odor. The rehydrated dried products were acceptable by the sensory panelists and were preferred in the order: FD, VD, AD, MVD. Gas chromatography-mass spectrometry revealed that drying significantly decreased the n-alkanals and 1-octen-3-ol content (p < 0.05) and produced new aldehydes including 2-methyl-propanal, 3-methyl-butanal, and furfural in MVD products. This study demonstrated that drying restructured fish meat can be potentially used to develop the new dried fish products using optimal drying conditions.

Thin layer electrohydrodynamic (EHD) drying and mathematical modeling of fish

The main objective pursued in this paper is to investigate the single layer drying behavior of fishslices experimentally in an electrohydrodynamic (EHD) dryer and also to perform mathematical modeling. Drying experiments of fish slices were studied at 10, 15, 20, 25 and 30 ◦ C, relative humidity of 30%, 40%, 50%, 60% and 70%, drying voltage from 5 kV to a maximum voltage of 50 kV in increments of 5 kV, the moisture content of fish slice for constant sample thickness (8 mm), and the samples thicknesses from 2 mm to a maximum 16 mm in increments of 2 mm in a EHD dryer. Sample weight, drying rate were measured during drying and drying rate curves were obtained for each experimental data. The drying rate data were performed using seven different mathematical models to estimate a suitable model according to their correlation coefficient (R), determination coefficient (R 2 ) and standard error (S), which were predicted by linear and non-linear regression analysis using SPSS computer program. It was deduced that the quadratic model were found to satisfactorily describe the drying rate of fish with the drying voltage, ambient temperature and drying time, respectively. However, the exponential model was the most suitable model to describe the drying rate of fish with the relative humidity, the moisture content and the thickness of fish slices, respectively.

Kudoa iwatai and two novel Kudoa spp., K. trachuri n. sp. and K. thunni n. sp. (Myxosporea: Multivalvulida), from daily consumed marine fish in western Japan

Infection of marine fish by certain myxosporean species of the genus Kudoa results in unsightly cyst formation in the trunk muscle or post-mortem myoliquefaction, causing a great economic loss to aquaculture industries, capture fisheries, and fish dealers. In addition, consumers encountering unsightly Kudoa cysts in fish fillets believe them to be unknown foreign materials acquired during processing. To identify prevalent Kudoa spp. encountered in daily life by the Japanese population, fresh fish slices (sashimi) or fish fillets with whitish spots were collected during a 7-month period (May to December 2008) at local markets in the city of Yamaguchi, western Japan. Kudoa cysts were found in three Japanese seaperches (Lateolabrax japonicus), two black sea bream (Acanthopagrus schlegelii), two Japanese jack mackerel (Trachurus japonicus), and one albacore (Thunnus alalunga). Kudoa iwatai was identified in all the examined Japanese seaperch and black sea bream from Japan's Inland Sea, as assessed by morphology and genetic analysis of the 18S and 28S ribosomal RNA gene (rDNA). Kudoa trachuri n. sp. from two Japanese jack mackerel fished in the Japanese Sea off Nagasaki and Kudoa thunni n. sp. from one albacore fished in the Pacific Ocean had a spore, which was semiquadrate in shape in apical views and ovoid in lateral views, with four equal shell valves and drop-like polar capsules. Scanning electron microscopy revealed that these three Kudoa species had different types of small projections at the apex of each valve. The 18S and 28S rDNA sequences of K. trachuri n. sp. and K. thunni n. sp. were found to be closely related to those of Kudoa crumena; however, these sequences were distinct in each of the species, which additionally exhibited different morphological features.

Kinetic properties of saxitoxin in Atlantic salmon ( Salmo salar) and Atlantic cod ( Gadus morhua)

The disposition of STX in Atlantic salmon ( Salmo salar) and Atlantic cod ( Gadus morhua) was studied after intraperitoneal (IP) injection (5 μg STX/kg bm and 3.43 μg 3H-STXeq/kg bw respectively), intravenous (IV) injection (5 μg STX/kg bm, only salmon) and waterborne exposure (50 μg STXeq/L, only salmon). Plasma concentrations in salmon were quantified using a receptor binding assay and cod tissues were analyzed using scintillation counting of tissue extracts and autoradiography of whole fish slices. The estimated elimination half-life (T 1/2) after IV administration of STX in salmon was 102.6 min. The volume of distribution (Vz) was observed to be 467.2 mL/kg and the total body clearance (Cl T) was 3.2 mL/min/kg. Waterborne exposure clearly showed that salmon absorbed PSP toxins directly from the water. In cod, 3H-STX was observed in gills, muscle, brain, liver and posterior kidney from 30 to 480 min. The lowest concentrations of 3H-STX were found in brain and muscle, whereas posterior kidney contained the majority of the toxin. Autoradiograms confirmed the high levels of 3H-STX in the kidneys, indicating that renal excretion was the main elimination route. Buildup of harmful levels in edible tissue is not very likely due to the low concentrations accumulated in muscle tissue and rapid excretion.

Effect of Hot Smoking on the Content of Selected Polychlorinated Biphenyl Congeners in Herring (Clupea harengus) Slices

Herring ( Clupea harengus) (as well as sprat and mackerel) is a fish species intensively harvested by the Polish fishing fleet. Its relatively low price and the habits of Polish consumers contribute to its high economic importance in Poland. Among 125.6 thousand tons of marine fish harvested in 2006, herring constituted 22.2 thousand tons (including 7.6 thousand tons harvested from the North Sea). Fish are usually subjected to various culinary treatments, which can influence the concentrations of contaminants in final products. Therefore, the present study aimed at determining the effect of three non- ortho-polychlorinated biphenyl (PCB) congeners (PCB 77, PCB 126, and PCB 169) and three mono- ortho-PCB congeners (PCB 114, PCB 156, and PCB 157) in the tissues of herring slices. Concentrations of dry matter and lipids in the final product were increased by 15.9 and 20.5%, respectively. Brining, which preceded the process of smoking, did not significantly influence concentrations of PCB congeners in herring slices. However, smoking resulted in significant ( p < 0.05) changes in concentrations of three non- -ortho PCBs. The biggest dynamics of losses in relation to smoking duration was observed for PCB 77 (30.2%). For PCB 126, the biggest losses occurred after 1 h of drying, followed by slight changes after 1.5 and 2 h of proper smoking and another increase of losses in the final product after 2.5 h. The duration of smoking did not significantly influence PCB concentrations in wet weigh, as their losses in lipids were much bigger. The observation is derived from strong negative correlations between concentrations of the congeners in lipids and lipid concentrations in herring slices during hot smoking ( r ranging from -0.824 to -0.950). Although the lipid concentration in the smoked fish increased, the PCB content diminished. It shows that during drying of the fish slices, PCBs codistilled with water vapor, settling on the walls of the smoking chamber and smoking trolleys. During the proper smoking, the compounds released with the smoke back to the smoking chamber and settled on the surface of smoked fish together with the disperse phase of the smoke (aerosol). Hot smoking contributed to a reduction of toxic equivalents (TEQs) by 22.7% (converted into lipids 41.9%), and in the final product, it amounted to 0.0188 +/- 0.0023 ng TEQ/kg of wet weight (0.0977 +/- 0.0064 ng TEQ/kg of lipids). The reduction was significantly higher than resulting from hot smoking of mackerel slices, when TEQs were reduced by 17.9% wet weight (converted into lipids 31.7%).