Fresh Fish Muscle Research Articles

Health risk assessment attributed the consumption of fish and seafood in Belém, Pará, Brazil

BackgroundMercury is one of the metals responsible for environmental contamination and the intoxication of human beings, mainly due to the increasing use of mercury in the formation of amalgam, a metallic alloy formed by the reaction between mercury and metallic gold, which is often drained into the aquatic environment. AimTherefore, this study evaluated 20 species of fish and seafood, commercialized in the metropolitan region of Belém (Pará, Brazil). Materials and methodsMercury was quantified using DMA. The limits of detection and quantification obtained were 0.027 and 0.091 μg g-1, respectively. The fresh fish muscle samples (n = 3) were weighed in a nickel boat and placed in the autosampler of the DMA for the quantification of total Hg (THg). Method accuracy was realized and confirmed using fish protein-certified reference material for trace metals (DORM-4). ResultsThe mercury concentration (THg) of fish samples ranged from 0.003 to 0.209 μg g-1, pratiqueira, and codfish, respectively. Assessment of health risks associated with the ingestion of mercury present in fish was carried out from the Estimated weekly intakes (EWI), Target hazard quotient (THQ), and Maximum Safe Consuming Quantity (MSCQ). Consumption of fish and seafood may pose a non-carcinogenic and carcinogenic health risk. ConclusionThe value of THg concentrations in all species was within the regulatory limits for fish, except Corvina fish sample that was below the limit of detection. The RiskHg was less than 1, showing a low risk of mercury exposure. The PTWI ranged from 0.005 to 0.323 for a consumption of 173 g of fish. The THQ values found were lower than 1, showing that the samples studied do not have a carcinogenic effect when consumed. The MSCQ values obtained were considered high, since the index is related to the mass of 25 g of fish consumed daily. This study showed the importance of monitoring and assessing the health risk of mercury in fish and seafood consumed by the population.

EFFECT OF SEX, SEASON, AND SIZE ON THE CHEMICAL COMPOSITION OF RED SEA GOATFISH Parupeneus forsskali (Fourmanoir and Guézé, 1976) CAUGHT FROM THE MARINE WATER OF LATTAKIA GOVERNORATE (SYRIA)

The effects of seasonal and sexual differences and Total Lenght on the chemical composition of the Red Sea goatfish Parupeneus forsskali caught from the marine waters of Lattakia Governorate were investigated. Moisture, crude protein, crude fat, and ash were determined as a percentage of the fish muscles. The results revealed that the autumn season was the highest in terms of nutritional components (protein 22.08%, fat 9.78%, ash 2.42% of fresh fish muscle), While the Summer season was the lowest (protein 19.32%, fat 5.46%, ash 1.20%). The results also showed the superiority of females in the values of the nutritional components over males, where the values were for females (protein 22.3%, fat 8.9%) and males (protein 20.7%, fat 6.8%), while The results also showed the superiority of males in the values of ash over females of ash (male 1.5%, female 1.3%). Regarding the body length factor, the results showed a significant positive relationship between an increase in Total length and an increase in protein and fat and a significant inverse relationship with both ash and moisture content.

Biochemical and Organoleptic Assessment of Asian Stinging Catfish (Heteropnuestes fossilis) in Two Storage Conditions

The proximate composition, rigor-index, organoleptic quality, and pH of Asian stinging catfish stored at iced condition (SIC) and stored at ambient temperature (SAT) were studied. Rigor mortis for both ice and ambient temperature started immediately after death and the rigor-index was maximum 82.35 % and 63.42% at 4 hrs and 8 hrs storage in SIC and SAT, respectively. Fish SIC showed a remarkably extended maximum rigor-index period of 14 hrs and 2 hrs in fish SIC and SAT, respectively. Fish SIC showed post-rigor period for upto 30 hrs, it was shorter in fish SAT for 18 hrs, though in both storage the rigor-index of the fish did not ceased completely. The moisture, protein, lipid, and ash content of fresh, SIC and SAT fish were 77.30%, 75.57%, and 78.81%, 15.04%, 15.34%, and 14.42%, 6.10%, 6.30%, and 3.47%, 1.99%, 2.67%, and 2.95%, respectively. The initial pH of fresh fish muscle was 6.89 which decreased to 6.32 and 6.12 after 18 hrs in fish SIC and SAT, respectively. The organoleptic quality assessment was in acceptable condition up to 12 days in fish SIC whereas a very short period of 10 hrs at fish SAT. Considering the findings of present study, it is highly recommended to store Asian stinging catfish at iced condition for maintaining shelf-life and quality.

Quality Changes of Salt-Smoke-Dried Tengra (Mystus tengara) during Storage at Room Temperature (28 To 32°C) in Different Packs

Packing has effect on the quality parameters of a food product. Here, studies were conducted to produce premium quality salt-smoke-dried tengra fish (Mystus tengra) by combining the effect of salt and smoke in a smoking kiln. During the study, moisture content in tengra fish fell from an initial value of 77.17% to a range of 18.56% to 29.09%, protein content from 51.36% to a range of 40.54% to 51.36%, lipid content from 16.20% to a range of 6.50% to 16.20% and ash content from 13.40% to a range of 8.17% to 13.40% for salt-smoke-dried products at the end of the storage period. On the other hand, the TVB-N value of fresh fish muscle was obtained 2.90 (mg/100g), pH 6.80 and bacterial load 1.13×104 (CFU/g), with the progress of storage period 180 days which values increased to the range of 28.16 to 29.34 mg/100g, 6.27 to 7.86 and 4.42 ×105to 6.82 x 105CFU/g, respectively. From the obtained results this study could be concluded that- if tengra is salted, smoked and dried properly can be stored at room temperature (26 to 28°C) for about 6 months without major deterioration of the fish and among three packs vacuum pack might be better option for storing salt-smoke-dried tengra.
 Environ. Sci. & Natural Resources, 12(1&2): 191-197, 2019

Study on assessment of proximate composition and meat quality of fresh and stored Clarias gariepinus and Cyprinus carpio.

The organoleptic evaluation and proximate analysis of Clarias gariepinus and Cyprinus carpio were determined in fresh fish and when refrigerated at two different temperatures (-21 °C and 4 °C) for a period of six weeks. A panel of twelve trained judges evaluated the color (live), texture, softness and flavor of fish meat after two minutes' steam cooking. Average score revealed a general decline in organoleptic properties such as color, texture, freshness, and taste of C. gariepinus and C. carpio stored at two temperatures compared to the fresh fish. Proximate analysis revealed a more decrease in crude protein and lipid contents and increase in ash content in C. gariepinus and C. carpio at the two storage temperatures compared to the fresh fish muscle. Moisture content decreased in the fish muscle samples of both the fish species stored at -21 °C but increased in the 4 °C stored samples. pH of fish was found to increase in the two stored temperatures. There were significant differences (P<0.05) in the organoleptic and proximate composition of the ice stored and fresh C. gariepinus and C. carpio, the same temperature and between the two different temperatures. The quality of fish muscle stored at 4 °C deteriorated faster than that of the -21 °C. Thus, storage temperature and duration have adverse effects on the nutritional quality of fish meat.

Organ-specific bioaccumulation of PCBs and PAHs in African sharptooth catfish (Clarias gariepinus) and common carp (Cyprinus carpio) from the Hartbeespoort Dam, South Africa.

The distribution of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the muscle, liver, spleen and kidney tissue of two fish species was studied using an optimised diatomaceous earth assisted modified QuEChERS extraction method. Five-year-old free-ranging male African sharptooth catfish (Clarias gariepinus) and 5-year-old male common carp (Cyprinus carpio) sampled from the Hartbeespoort Dam in South Africa were used for method development. Acetonitrile extraction produced more precise recoveries than hexane extraction. Fluorene and naphthalene were the most abundant PAHs detected in the majority of fish tissues analysed. PAH bioaccumulation in 5-year-old carp and 5-year-old catfish was in the order muscle > kidney > liver > spleen and liver > muscle > kidney > spleen, respectively. PCBs were mostly detected in carp spleen and kidney. Two-year-old carp were analysed to determine PCB and PAH bioaccumulation trends. The differences in ∑16PAH concentrations between the four organs tested were all statistically insignificant for the 3 fish tested (p > 0.05). All other organs with the exception of 5-year-old carp spleen and 5-year-old carp kidney recorded total 31 PCB concentrations (∑31PCB) < 25ngg-1. Only 5-year-old carp spleen (∑31PCB of 592ngg-1) and 5-year-old carp kidney (∑31PCB of 561ngg-1) had significant differences (p < 0.05) from the spleen and kidney in 5-year-old catfish and 2-year-old carp. Whilst the carp and catfish sampled can be considered low PCB risk foods, 5-year-old carp muscle can be considered to be a high PAH risk food, with a benzo(a)pyrene concentration of 7μgg-1, based on the EU Commission Regulation 2005/208/EC pertaining to the maximum permissible benzo(a)pyrene level in fresh fish muscle.

Direct speciation analysis of organic mercury in fish and kelp by on-line complexation and stacking using capillary electrophoresis

To determine organic mercury (Hg) species that could not be detected by ultraviolet (UV), a highly automated on-line complexation method was established, which combined with normal stacking by capillary electrophoresis-diode array detector. The approach was based on the fact that the compounds and complex reagent interacted to form hydrophilic chelates under the effect of the separation voltage, which was effectively separated and detected by UV. Key parameters, such as the type and concentration of complex reagent, separation voltage and so on were systematically investigated. Under the optimized conditions, the precision and repeatability were in the range of 0.16–3.31% and 0.17–1.21%, respectively. Furthermore, PhHg, EtHg and MeHg were effectively separated and determined in fresh fish (Silver carp) muscle and kelp (Kombu) with the recoveries of 84.63–111.39% and 75.68–114.76%, respectively. The proposed method had the advantages of easy-operating, cost-efficient, stable and reliable compared to off-line complexation method.

Analysis of 52 pesticides in fresh fish muscle by QuEChERS extraction followed by LC-MS/MS determination

Pesticide pollution in water has been well described; however, little is known on pesticide accumulation by aquatic organisms, and to date, most studies in this line have been focused on persistent organochlorine pesticides. For this reason, a method based on QuEChERS extraction and subsequent liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis has been developed and validated for the determination of 52 medium to highly polar pesticides in fresh fish muscle. Target pesticides were selected on the basis of use and occurrence in surface waters. Quantification is carried out following an isotope dilution approach. The method developed is satisfactory in terms of accuracy (relative recoveries between 71 and 120%), precision (relative standard deviations below 21%) and sensitivity (limits of determination in the pg/g or low ng/g f.w. range for most compounds). The application of the validated methodology to fish specimens collected from the Adige River (Italy) revealed the presence of trace levels of diazinon, dichlorvos and diuron, and measurable levels of metolachlor, quinoxyfen, irgarol, terbutryn, and acetamiprid, but in all cases at concentrations below the default maximum residue level of 10 ng/g established for pesticides not specifically regulated in fish intended for human consumption. Metolachlor and quinoxyfen were both the most ubiquitous and abundant pesticides, in agreement with their high potential for bioaccumulation. Both are toxic to aquatic organisms, and therefore, their potential effects on aquatic ecosystems should be further explored.

Endogenous level of acetic acid in yellowfin tuna (Thunnus albacares): a pilot study about a possible controversy on its residue nature

ABSTRACTA method based on headspace solid-phase microextraction (HS-SPME) followed by GC-MS analysis was developed for the determination of underivatised acetic acid in fresh tuna fish muscle. Parameters such as the fibre selected and the extraction time and temperature were optimised and the linearity, detection limits and precision of the whole analytical procedure were assessed. The method was then applied to determine the acetic acid concentration in fresh yellowfin tuna muscles (Thunnus albacares) in order to evaluate the endogenous level and its variations during the shelf life under different storage conditions. A qualitative comparison was also made with variations in histamine levels to evaluate the possibility of the joint monitoring of acetic acid and histamine to identify fish stored in poor conditions. The caudal area always had a lower content of acetic acid than the ventral area, independent of the storage time and temperature. A difference was found between the 6- and 3-day time points and day 0 at a storage temperature of 8°C and between the 6-day time point and day 0 at a storage temperature of 0°C, independent of the anatomical area of the sampled tissue. The evaluation of acetic acid could represent an important approach in the field of food safety to detect the illicit use of acetic acid as an antibacterial preservative treatment or to eliminate the unpleasant smell of trimethylamine.

Angiotensin I-converting enzyme (ACE) inhibitory activity and structural properties of oven- and freeze-dried protein hydrolysate from fresh water fish (Cirrhinus mrigala)

The angiotensin I-converting enzyme (ACE) inhibitory activity and structural properties of oven-dried (OD-FPH) and freeze-dried (FD-FPH) protein hydrolysates derived from fresh water fish (Cirrhinus mrigala) muscle, using papain, were investigated. Amino acid profiles indicated a higher proportion of hydrophobic residues in OD-FPH and hydrophilic residues in FD-FPH samples. Fourier transform infrared (FT-IR) spectra revealed random coil structure in OD-FPH and β-sheet in FD-FPH samples. The approximate molecular weight of peptides in OD-FPH and FD-FPH was in the range of 7030–339Da. The IC50 values for ACE inhibition by OD-FPH and FD-FPH samples were found to be 1.15 and 1.53mg of proteinml−1, respectively. The ACE-inhibitory activity of OD-FPH was more stable (during sequential digestion, using pepsin and pancreatin) than that of FD-FPH sample. The study suggested that the ACE inhibitory activity of protein hydrolysate was not affected by oven-drying.

Sensory, Microbiological, Biochemical and Physico-chemical Assessment of Freshness and Quality of Fresh Lake Malawi Tilapia (&lt;i&gt;Chambo&lt;/i&gt;) Stored in Ice

Sensory, microbiological, biochemical and physico-chemical methods were used to assess freshness and quality of fresh Lake Malawi Tilapia (Local name: Chambo) to compare their effectiveness and reliability. Fresh Chambo samples were rejected by the sensory panel after 16 days from day of catch with a strong linear correlation (P < 0.01, R 2 = 0.95) between sensory quality scores and storage time in ice. Highest bacterial load of 1.6×10 7 cfu/g, cfu/cm 2 was observed on day 15 coinciding with sensory rejection time. TMA-N and TVB-N for freshly caught fish was 0.7 and 5.1 mg/100g, which increased to 3.4 and 26.4 mg/100g respectively at the time of sensory rejection also correlating with increased bacteria load in the fish. Initial pH of the fresh fish muscle was close to neutral (6.47), and reached its lowest point (5.84) on day 16 which was sensory rejection time. Findings suggest that sensory evaluation is reliable in the absence of the other methods. TMA-N is not a reliable method for assessing freshness quality of Lake Malawi Tilapia due to insignificant readings. pH showed to be a quick freshness indicator with an understanding that muscle pH for live fish is generally neutral and increases as deterioration of the quality of fish progresses in storage. Rejection of fish samples before reaching unacceptable microbial limits in this study, underpins the need for using more than one method for accurate freshness and quality assessments of fresh fish.

A reliable liquid chromatography–tandem mass spectrometry method for simultaneous determination of multiple mycotoxins in fresh fish and dried seafoods

A reliable liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for simultaneous determination of nine mycotoxins, i.e., aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2), ochratoxin A (OTA), zearalenone (ZEN), T-2 toxin, HT2 toxin and deoxynivalenol (DON), in fresh fish (muscle and entrails) as well as dried seafoods. Special focus was given to sample pretreatment which is crucial for an accurate and reliable analytical method. With regards to the high complexity of the matrices, extraction solvent, time, and temperature as well as clean-up cartridges were optimized to improve extraction efficiency and reduce matrix effects. The optimum procedure included ultrasound-assisted extraction with acetonitrile/water/acetic acid (79/20/1, v/v/v) at 40°C for 30min, defatting with n-hexane and purification by Oasis HLB cartridges. The method was further validated by determining the linearity (R2≥0.9989), sensitivity (limit of detection ≤2μg/kg, limit of quantitation ≤3μg/kg), recovery (72.2–119.9%) and precision (≤18.3%) in muscle and entrails of fresh crucian carp (Carassius carassius) as well as dried fish products. The method was proven to be suitable for its intended purposes. Mycotoxins of OTA, ZEN and AFB2 have been found in fresh fish and dried seafoods for the first time.

Antioxidant effect of &lt;i&gt;Citrullus vulgaris&lt;/i&gt; (watermelon) extract against lipid oxidation in fish during cooking

The Antioxidant effect of Citrullus Vulgaris (Watermelon) extract was evaluated against lipid oxidation in freshly caught fishes during cooking. GC-MS analysis of Hexane and total phenolic extract of Citrullus Vulgaris flesh reveals that the extracts contain 55 compounds which includes 5- hydroxymethyl furfural, 4H-Pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl-, Hexadecanoic acid, ethyl ester and Palmitic acid ester that are reported as antioxidants. Muscle flesh of fifteen (15) samples of freshly caught fish comprising Group I (Tilapia zilli; n=5), Group II (Clarias hollandis; n=5) and Group III (Clarias gariepinus; n=5) were prepared and Sub Grouped each as Control, Treatment 1, Treatment 2, Treatment 3 and Treatment 4 which receives 0, 50, 150, 250 and 450mg of Citrullus Vulgaris extract per 100g fresh fish muscle weight respectively. Treatment 4 gave the highest protection against lipid oxidation in all groups, however the concentration of MDA in Treatment 3 of Group I and III were not significantly (p&gt;0.05) higher as compared to Treatment 4 of same Groups. The results clearly suggested that the extract effectively prevented lipid oxidation in fish and that the rate of prevention is a factor of fish species and extract concentration.Keywords: Fish, citrullus vulgaris, lipid oxidation, Antioxidants, Malondialdehyde (MDA)

General validation of formalin‐preserved fish samples in food web studies using stable isotopes

Summary Stable isotope analyses of carbon and nitrogen are widely used to study food web structure in ecosystems. However, isotopic signatures are affected by the often‐needed chemical preservation of tissues in the field, which impedes or weakens the interpretation of results. The scarcely available correction factors for preserved fish samples are species specific and have so far not been validated for general use. Moreover, no studies have evaluated the effect of preservation on the estimation of metrics typically used in food web studies. We aimed to develop a general correction model suitable for a vast number of fish species and to test whether formalin‐preserved fish muscle δ13C and δ15N values can be used in food web metrics estimations. For this purpose, we used paired formalin‐preserved and fresh muscle samples of 116 fish individuals belonging to 17 species covering a wide range of fish trophic characteristics, from nine tropical streams. Formalin decreased δ13C values by 0·6–1·4‰ (0·94‰ on average) and increased δ15N values by 0·3–0·5‰ (0·33‰ on average). Preservation effect was ecologically significant for δ13C values (as it surpassed natural trophic fractionation) and less important for δ15N values (being minor than natural trophic fractionation). However, preservation did not affect estimation of community‐wide food web metrics. The deviations in preserved samples varied among species and increased with increasing fresh sample C : N ratios and changes in carbon proportions after preservation and with increasing isotopic values (for δ13C). Despite these major deviations in δ13C values, we developed and validated a powerful general linear model to predict fresh fish muscle isotopic signatures from preserved samples. Formalin‐preserved samples of fish can be used in food web studies, simplifying sampling logistics and allowing the use of museum and scientific collection specimens for historical food web reconstruction. Food web metrics based on δ13C vs. δ15N biplots can be directly estimated from preserved samples as the preservation effect seems overall consistent. When more detailed information is needed, or fresh and preserved samples are being simultaneously studied, formalin‐preserved isotopic signatures can be corrected to fresh values using the model developed in this study.

Change In Proximate Composition And Microbial Count By Low Temperaturepreservation In Fish Muscle Of Labeo Rohita(HamBuch)

The study was designed to investigate the effect of low temperature preservation on the chemical and microbial profile of fish muscle (Labeo rohita) stored for a period of twenty one days. The proximate composition and microbiological analyses were carried out at 7 days interval on muscle of fish during frozen storage. It was found that the protein, lipid, moisture and ash contents decreased significantly (P < 0.05) during the entire storage period. In fresh (unfrozen) samples, protein(15.93±0.04%), fat (3.86±0.04% ), moisture (84.74±0.1%.),and ash content (1.79±0.01%) were found to be the highest ,where as the total percent decrease in frozen samples on 21 st day of frozen storage was (12.99% ), (22.27%) , ( 4.60% ) and (24.02% ) for protein, fat, moisture and ash respectively. The microbial count increased gradually during the period of storage. The Total Plate Count in fresh fish muscle on day zero was rather low i.e. 2.44±0.2 log cfu/g as compared to the values found on the 21 st day i.e. 5.10±0.02 log cfu/g. The Coliform Count also followed the same trend during the storage. On day zero, a few colonies were found and the CC was 1.50±0.15 log cfu/g where as it increased up to 3.08±0.07 log cfu/g on last day of storage. Similarly Psychrophillic count increased from 2.15±0.2 log cfu/g on day zero to 5.06±0.05 log cfu/g on 21 st day. Thus, a significant quality loss was observed in fish during storage. However, the present frozen conditions retained the fish under acceptable microbial conditions for human consumption up to 14 th day beyond which it became unfit for human consumption.

Matrix Solid Phase Dispersion‐Accelerated Solvent Extraction for Determination of OCP Residues in Fish Muscles

AbstractA rapid, sensitive and accurate matrix solid phase dispersion‐accelerated solvent extraction (MSPD‐ASE) method for selective determination of sixteen organochlorine pesticide (OCP) residues in fish samples has been developed and validated. 2 g fresh fish muscle was dispersed with 10 g anhydrous sodium sulfate and 2 g acid alumina thoroughly, and loaded into the stainless‐steel extraction cell containing 6 g of acid alumina and 10 g anhydrous sodium sulfate. The temperature 60 °C and two extraction cycles of 5 min gave adequate extraction efficiency using DCM‐hexane (3:7, v/v) mixture as solvent. Not only the lipids, but also other co‐extracts, which peaks mostly located in the forepart of chromatograms and maybe interfere the identification or quantitation of analytes, were eliminated exhaustively, while analytes were extracted selectively. Sixteen OCPs were identified by retention time of standards and quantified using mirex as internal standards. These detected OCPs were confirmed by GC‐MS in real samples. The performance of proposed method was evaluated and validated: the detection limits were 0.008‐0.05 ng g‐1, relative standard deviations were 1.9‐5.0%, and recoveries were 91.0‐104.1% spiked at 10 ng g‐1 level. The accuracy and precision of proposed method were equal to or better than that of traditional Soxhlet extraction method.

EFFECT OF HEAT TREATMENT ON THE NUTRITIVE VALUE AND RESIDUES OF SOME SYNTHETIC PESTICIDES IN FRESH BOLTI FISH

Fresh Bolti fish (Tilpia nilotica) collected randomly from 9 different markets in Ismailia Governorate for evaluation the effect of grilled fish by the method used in grillrooms and houses on the concentration of pesticide residues found and the nutritive value. Results revealed that decrease in the estimated parameters i.e. moisture, crude protein, fat and ash by grilling, this decrease were 6.07, 2.63, 4.07 and 1.56%, respectively. On the contrary, carbohydrates behaved another behavior that there was an obvious increase ranged from 1.98% to 2.92%. Fresh and grilled fish were analyzed to detect 12 organochlorine (OC) and 7 synthetic pyrethroid (SP) pesticides with a mean level on a lipid basis. Gas Liquid Chromatography equipped with Electron Capture Detector GC-ECD was used to detect the contamination in the samples. The results showed that p,p'-DDE isomer was dominated over the other isomers in all analyzed fish samples, followed by a-isomer of hexachlorocyclohexane. The concentrations of OC residues were higher than SP pesticides in all fish muscles. Also, the fresh fish muscle recorded higher concentrations of the evaluated pesticides than the grilled one.

Simultaneous voltammetric analysis of tetracycline antibiotics in foods

The new simple, cost effective and well performing differential pulse stripping voltammetry method for the simultaneous determination of antibiotics – oxytetracycline, tetracycline and chlorotetracycline was researched and developed. It depends on the reduction of these compounds at a hanging mercury drop electrode. The samples were extracted from (i) spiked animal feed, and (ii) fresh fish muscle dosed with the drugs. The voltammograms from the drug mixture produced complex, overlapping profiles, and chemometrics methods were applied for calibration modelling. The analytical linear ranges were within 0.02–0.18 μg mL −1 and the corresponding LODs were 3–5 μg L −1 for the three analytes. These values compare well with those from the HPLC and fluorescence methods in the literature. The % relative prediction errors from the verification trials were between 4% and 9% with % Recoveries being 103–107. Also, the % Recoveries of the antibiotics from animal feeds as measured by the new method were comparable with those from the HPLC analysis (85%), i.e. the method is highly competitive, especially as a screening approach.

DESCRIPTIVE STUDY OF REFLECTANCE SPECTRA OF HAKE (MERLUCCIUS AUSTRALIS), SALMON (SALMO SALAR) AND LIGHT AND DARK MUSCLE FROM TUNA (THUNNUS THYNNUS)

ABSTRACT The reflectance spectra of foods constitutes a simple, non‐destructive physical method with potential applications in the industry. Color is the most valued properties for customers when buying fresh fish, so that its characterization is important for setting objective quality criteria that can be easily applied at all levels of the production and distribution chain. In this work the reflectance spectra and CIEL*a*b* coordinates of fresh muscle in hake, salmon and tuna (light and dark muscle) it was described. Hake, salmon and the dark tuna muscle show a zone of the spectrum (between 600 and 740 nm) with no significant (P &gt; 0.05) differences between the reflectance percentages, which may be taken as characteristic of fresh fish muscle. The light tuna muscle shows a plateau between 700 and 740 nm, while the dark muscle presents a further two plateaus between 390 and 440 nm and between 470 and 510 nm.PRACTICAL APPLICATIONSThe study of the reflectance spectra of fish is a method with many potential applications in the food industry. Spectrum shape is characteristic of each fish. For this reason, a study of the reflectance spectra of the “fresh meat” of commercially interesting fish species could be of value as tool for characterizing fish and fish products. In each case it will be necessary to identify the characteristic wavelengths or spectral regions that provide the “digital footprint” of the species in question. Its characterization is important for setting objective quality criteria that can be easily applied at all levels of the production and distribution chain.

Collagen content in farmed Atlantic salmon (Salmo salar L.).

To clarify fish flesh quality problems and softening of fish muscle tissue during chilled storage, the collagen content, types I and V, and its changes in solubility during storage on ice in muscle of farmed Atlantic salmon (Salmo salar L.) were analyzed. The contents of acid-soluble, pepsin-soluble, and insoluble collagen in white muscle were determined in fresh fish muscle and after 3 days of storage in ice. The total collagen content was 2.9 g kg(-)(1) fresh weight. During storage on ice, a progressive change in solubility of muscle collagen was found. For acid- and pepsin-soluble collagen fractions, significantly higher and lower values, respectively, were detected. The presence and quantification of types I and V collagen in the different collagen fractions was determined also, but no significant difference in solubility during storage was found. The result suggested that collagen fibers of Atlantic salmon have a high solubility in acid solutions and contain few cross-links.