Catfish Fillets Research Articles

Levels of polychlorinated dibenzo- p-dioxins, dibenzofurans, and biphenyls in southern Mississippi catfish and estimation of potential health risks

Fish consumption has been classified as one of the primary pathways of exposure to polychlorinated dibenzo- p-dioxins, dibenzofurans (PCDD/Fs) and biphenyls (PCBs). In this study, we evaluated tissue levels of the 17 laterally substituted PCDD/Fs, 12 dioxin-like PCBs, and 97 non-dioxin-like PCBs in a number of wild-caught and farm-raised catfish collected throughout southern Mississippi. Total lipid-adjusted TEQ and non-dioxin-like PCB concentrations in wild-caught catfish fillets were significantly higher than concentrations in farm-raised fillet samples. The percent contribution of PCDDs, PCDFs, and dioxin-like PCBs to mean total TEQ varied between wild-caught and farm-raised samples as well as by collection site for wild-caught catfish. The non-dioxin-like PCBs that contributed the most to total PCB concentrations also differed between wild-caught and farm-raised samples. Regardless of whether samples were farm-raised or wild-caught, estimated cancer risks associated with consumption of these catfish were less than 27.0E−06. Overall, results of this study indicate that levels of dioxin-like compounds and PCBs in Mississippi catfish are similar to those measured in more recent studies in the US and that levels of these compounds appear to be decreasing in this food source.

Microbial quality of raw aquacultured fish fillets procured from Internet and local retail markets.

The microbial quality of raw fillets of aquacultured catfish, salmon, tilapia, and trout was evaluated. A total of 272 fillets from nine local and nine Internet retail markets were tested. Mean values were 5.7 log CFU/g for total aerobic mesophiles, 6.3 log CFU/g for psychrotrophs, and 1.9 log most probable number (MPN) per gram for coliforms. Differences in these microbial levels between the two kinds of markets and among the four types of fish were not significant (P > 0.05), except that Internet trout fillets had about 0.8-log higher aerobic mesophiles than did trout fillets purchased locally. Although Escherichia coli was detected in 1.4, 1.5, and 5.9% of trout, salmon, and tilapia, respectively, no sample had > or = 1.0 log MPN/g. However, E. coli was found in 13.2% of catfish, with an average of 1.7 log MPN/g. About 27% of all fillets had Listeria spp., and a positive correlation between the prevalence of Listeria spp. and Listeria monocytogenes was observed. Internet fillets had a higher prevalence of both Listeria spp. and L. monocytogenes than did those fillets purchased locally. L. monocytogenes was present in 23.5% of catfish but in only 5.7, 10.3, and 10.6% of trout, tilapia, and salmon, respectively. Salmonella and E. coli O157 were not found in any sample. A follow-up investigation using catfish operation as a model revealed that gut waste exposed during evisceration is a potential source of coliforms and Listeria spp.

New trends in the seafood market. Sutchi catfish (Pangasius hypophthalmus) fillets from Vietnam: Nutritional quality and safety aspects

Sutchi catfish (Pangasius hypophthalmus) produced in the freshwater basins of Vietnam, available on the Italian market as frozen or thawed fillets, were studied for their nutritional quality and safety aspects. Proximate composition, mineral content, fatty acid profile, unsaponifiable components of the lipid fraction and drip loss during thawing at 5°C were determined on the fillets. Fillets were characterised by high moisture levels (80–85%) and low protein (12.6–15.6%) and lipid (1.1–3.0%) contents. Total lipids were characterised by low cholesterol levels (21–39mg/100g), high percentages of saturated fatty acids (41.1–47.8% of total fatty acid) and low percentages of polyunsaturated fatty acids (12.5–18.8% of total fatty acids), which were mainly represented by linoleic acid (44–59% of total polyunsaturated fatty acids). The mineral composition was characterised by a high sodium content (222–594mg/100g), probably partially due to the sodium tripolyphosphate (E 451) used to retain moisture. As regards safety aspects, the quality of the samples analysed was good, with low residue levels of mercury, organochlorine pesticides and polychlorinated biphenyls.

Competition Between Imported Tilapia and US Catfish in the US Market

This paper investigates the competition between domestic catfish fillets and imported tilapia fillets in the US market. The market segmentation between fresh and frozen fillets of both species is also considered. The substitutability between catfish and tilapia is of interest because market reports have recently suggested that the rapid increase in tilapia imports in the last few years is the result of tilapia taking market share from domestically produced catfish. The competition between fresh and frozen fillets of catfish and tilapia imports in the same market is examined using market integration and demand analysis. The results indicate that imports of fresh and frozen tilapia fillets lie in different market segments, while fresh and frozen catfish fillets compete in the same market. Furthermore, fresh and frozen fillets of catfish and tilapia imports do not compete in the same market.

Evaluation of textural properties of channel catfish ( Ictalurus punctatus Rafinesque) fillet with the natural contour method

A value-added channel catfish ( Ictalurus punctatus Rafinesque) product was being developed to explore more profit for this industry. Textural properties played an important role in the quality control and acceptability of both raw and processed products. Due to insufficient study on this topic a reliable method was needed for textural properties evaluations of catfish and other small-scale fish. Textural properties of raw and smoked channel catfish ( I. punctatus) fillets were measured by the “finger” and “tooth” methods with a Texture Analyzer. A novel sampling technique was used to sample thickness contours on the fillets. Indentation force ( g) of the “finger” method and shear force ( g) of the “tooth” method were measured at different contour levels of four myomere cone bands on the fillets. Shear force and indentation force of the fresh catfish fillets increased with the increasing thickness as measured by the “tooth” and “finger” methods. Both methods could be used to measure the textural properties of catfish fillet. The “finger” method was recommended because of its non-destructive nature and applicability to both raw and smoked catfish samples. The novel sampling technique used in this study was rapid and applicable to irregular fillet shapes including catfish and other fish species. Smoked catfish had decreased indentation force with increased thickness. The dehydration effects and denaturization of fish muscle during the smoking process were main reasons for that.

Freezing‐thawing effects on the colour and texture of European catfish flesh

SummaryThe freezing‐thawing effect on the colour of raw fillets and on the texture of cooked fillets of European catfish (Silurus glanis) was studied. European catfish coming from two rearing conditions occurring in France were analysed by sensory and instrumental measurements. Fillets of European catfish became lighter, yellower and less bright after a freezing‐thawing cycle. An increase in hardness and a decrease in resilience, disintegration and shear resistance were also highlighted after a freezing‐thawing cycle. We could make the hypothesis that these variations of colour and texture were due either to mechanical damage or muscle protein denaturation. Fillets also became less juicy after a freezing‐thawing cycle because of a loss of water‐holding capacity.

Retention of health-related beneficial components during household preparation of selenium-enriched African catfish (Clarias gariepinus) fillets

Industrial processing and heat treatment of fish muscle generally lead to losses of water-soluble components, some of which may have beneficial health effects. The aim of this work was to determine the retention of taurine, selenium and n-3 polyunsaturated fatty acids when preparing African catfish by three traditional household techniques: boiling in pouches, deep-frying and baking. Cooking did not significantly reduce the content of selenium, having retention between 91and 104%. Deep-frying resulted in a taurine loss of 40%, which was significantly higher than in baking where losses were 25% The fatty acid profiles were similar for baked and boiled fillets, but were significantly different from deep-fried fillets, due to absorption of vegetable frying oil. Baking was the best preparation technique with regard to retention of 20:5n-3 (eicosapentaenoic acid; EPA) and 22:6n-3 (docosahexaenoic acid, DHA), retaining above 80% for both fatty acids, whereas boiling and deep-frying were able to retain only approximately 54 and 65% of each, respectively.

Pilot Plant Scale Production of Protein from Catfish Treated by Acid Solubilization/Isoelectric Precipitation

Catfish fillets were minced and acid (pH 3.0) solubilized in dilute conditions (1:9). Insolubles were removed by centrifugal force (3000 xg) and the soluble protein was recovered by isoelectric precipitation (pI approximately 5.4). Moisture and NaCl of the batters were equilibrated to 78% and 2%, respectively. Samples were stuffed into casings, cooked, and chilled. Proximate composition, color, cook yield, water holding ability (WHA), and texture profile analysis (TPA) were determined. Treatment of catfish protein by the solubilization process removed 74% of the fat. In addition, gels from treated protein were less red (-1.61 compared with -1.06) and yellow (6.58 compared with 7.09). There was no difference in whiteness (72.0 compared with 71.8) of gels or in percent cook yield (94.6% compared with 95.0%) between treated protein and the control, respectively. The WHA of gels made from control protein was 0.73 g/g protein higher than treated. The texture analysis indicated that treated proteins had significantly higher hardness (1193 g compared with 1046 g), springiness (0.919 compared with 0.897), chewiness (0.701 compared with 0.584), and cohesiveness (0.637 mJ compared with 0.619 mJ). The resilience was equivalent for both treated and control gels. The results indicated the protein solubilization process produced a low fat protein product with good gel strength properties.

Effect of different cooking methods on the oxidation, proximate and fatty acid composition of silver catfish ( Rhamdia quelen) fillets

The influence of seven cooking methods (boiling, conventional baking, microwave baking, grilling, deep-frying in soybean oil, canola oil, or partially hydrogenated vegetable oil) on the oxidation, proximate and fatty acid composition of silver catfish ( Rhamdia quelen) fillets was evaluated. All the treatments reduced moisture and increased the protein content. The free fatty acid content of the fillets was significantly reduced by the different cooking methods, while conjugated diene levels and peroxide values decreased for all fried samples, but remained constant in the samples subjected to the other cooking methods. Boiling and baking increased thiobarbituric acid reactive substances (TBARS), while grilling and frying did not change TBARS. Boiling, baking, and grilling did not affect the silver catfish fillets fatty acid composition. Frying in canola oil increased n−3/ n−6 ratio, while frying in soybean oil increased the general polyunsaturated fatty acid content, and frying in hydrogenated vegetable oil incorporated trans fatty acids in the fillets.

Ozone Applications in Catfish Processing

TVA, EPRI, Global Energy Partners, LLC, ClearWater Tech, LLC and Superior Catfish Products (Macon, Mississippi) partnered to conduct research and demonstrate beneficial effects of applying gaseous and aqueous ozone in catfish processing. Utilizing an HDO3-III skid mounted ozone unit manufactured by ClearWater Tech, LLC, various processing areas in the Superior Fish Products catfish processing plant were evaluated in August 2005 to determine if aqueous ozone could reduce the microbial load in the processing line and on finished product. In the offal room, gaseous ozone was introduced to determine if odors could be reduced while catfish by-products were being loaded into trucks also located in the offal room. The utilization of aqueous ozone as a final rinse for processing equipment was also tested. All tests were replicated five times and a completely randomized design was used to statistically analyze resulting data. Standard Laboratories, Inc. of Starkville, MS was contracted to conduct all microbial analyses. It was found that aqueous ozone was very effective in significantly reducing microbial loads on live catfish entering the plant. Finished catfish fillets washed in ozonated water showed significant reductions in total plate counts. Ozonation at the fillet machine could be beneficial. Utilizing aqueous ozone as a final wash after using soap and a chlorine sanitizer was of no benefit and actually removed the residual chlorine and led to increased plate counts. Gaseous ozone reduced odors in the offal room rapidly and effectively. Utilization of ozone for odor reductions will require ozone monitoring equipment that ensures employee safety.

Influence of farming conditions on colour and texture of European catfish (Silurus glanis) flesh

AbstractThe colour of raw fillets and the texture of cooked fillets of European catfish (Silurus glanis) were studied. The catfish fillets resulted from two types of farming conditions used in France. Sensory and instrumental analyses were performed on the fillets. Two farming parameters were found to affect the colour and texture of European catfish fillets: water temperature and farming time. The shorter the farming time was, the lighter the fillets were, while a higher water temperature produced yellower and greener fillets. A higher water temperature and a longer farming time produced softer cooked fillets, while the higher the water temperature was, the less juicy the cooked fillets were. A good correlation and complementarity were observed between sensory and instrumental analyses of the colour and texture of European catfish fillets. Copyright © 2007 Society of Chemical Industry

Effects of rested-harvest using the anesthetic AQUI-S™ on channel catfish, Ictalurus punctatus, physiology and fillet quality

Trials were conducted to determine effects of AQUI-S™ sedation during harvest (rested-harvest) on physiological responses and fillet quality of channel catfish, Ictalurus punctatus. Rested-harvest is defined as application of an anesthetic immediately before harvest to reduce fish activity associated with a normal harvest. Doses of 25–35 ppm AQUI-S™ were effective for rested-harvest of catfish (loss of equilibrium in 3 to 10 min and 100% survival following recovery). Time to loss of equilibrium and time to recovery following sedation with 35 ppm AQUI-S™ increased as water temperature decreased from 30 °C to 10 °C. Catfish exposed to 25 ppm AQUI-S™, 35 ppm AQUI-S™, 100 ppm trincaine methanesulfonate, and 8 ppm metomidate had lower blood lactate, cortisol, and glucose and higher blood pH than unsedated fish exposed to a low-water stress. Rested-harvest (RH) catfish had higher muscle and blood pH, lower blood and muscle lactate, and higher muscle ATP levels than catfish exposed to a 45 min low-water stress. Rates of muscle pH decrease, ATP decrease, and lactate increase accelerated as storage temperature decreased from 15 °C to 5 °C in RH fish acclimated to summer temperatures (33 °C), conversely these rates accelerated as storage temperature increased from 5 °C to 15 °C in RH fish acclimated to winter temperatures (7 °C). Based on physiological response (higher muscle pH, lower blood lactate, delayed time to rigor), post-sedation euthanasia by CO 2 was superior to post-sedation euthanasia by AQUI-S™ overdose (150 ppm), nitrogen gas, or electrical stunning. Compared to fillets from fish exposed to simulated industry transport conditions, fillets from RH/CO 2 euthanised fish had higher pH 1 h post-slaughter, and less drip-loss and lower L ⁎ and a ⁎ color values during 7 days of iced storage. RH/CO 2 and control fillets were not different for shelf-life based on bacterial counts. Rested-harvest with AQUI-S™ followed by CO 2 euthanasia has potential to improve catfish fillet quality, but AQUI-S™ approval, development of rested-harvest strategies, and demonstration of economic benefits of rested-harvest will be required for adoption of rested-harvest to commercial catfish production.

Influence of rearing conditions and feed on the biochemical composition of fillets of the European catfish ( Silurus glanis)

The biochemical composition of European catfish ( Silurus glanis) fillets reared under two conditions used in France was studied. The biochemical composition of the two feeds used was also analysed, in order to establish a relationship between European catfish fillet composition and feed. Dry matter, protein, lipid and carbohydrate contents were determined. The fatty acid profile was determined by GC-FID and GC/MS. This work has established that European catfish has a biochemical composition characteristic of semi-fat fish, that the protein content is affected by water temperature, and that the lipid content depends largely on feed. This work has also highlighted that the proportions of fatty acids can be affected by rearing conditions, by feed, or by both rearing conditions and feed with a significant interaction between these two factors.

Chemical and biochemical changes of hybrid catfish fillet stored at 4 °C and its gel properties

Chemical and biochemical changes of aquacultured hybrid catfish fillet ( Clarias macrocephalus × Clarias gariepinus) and its gel-forming ability as affected by age and sex of fish along with storage time were investigated. Fillets were stored at 4 °C for 0, 3, 6, 9, 12 and 15 days. There was no significant effect of sex and age of fish as well as storage time on fat, moisture and ash contents ( P > 0.05). The total protein, water soluble protein, and salt soluble protein contents of the fillets significantly decreased with storage time ( P < 0.05). On the other hand, pH, total volatile base nitrogen (TVB-N) and autolytic degradation products (ADP) increased as storage time continued ( P < 0.05). Decreases in Ca 2+-ATPase activity and gel properties were observed as storage time increased. However, there was no significant effect of either sex or age of fish on textural properties of gel ( P > 0.05). Hybrid catfish fillet stored at 4 °C should be processed within 6 days.

Enrichment of channel catfish ( Ictalurus punctatus) fillets with conjugated linoleic acid and omega-3 fatty acids by dietary manipulation

An experiment was conducted in aquaria with channel catfish ( Ictalurus punctatus) to determine the efficacy of augmenting fillets with conjugated linoleic acid (CLA) and omega-3 highly unsaturated fatty acids ( n − 3 HUFA) by feeding diets amended with products containing high levels of these nutrients. Refined menhaden fish oil at 1.5% of diet supplied the n − 3 HUFA. CLA was used at dietary levels of 0.5% and 1% with a preparation that contained approximately 65% isomers of CLA. Corn oil was added to the basal diet at maximum inclusion level for added lipids of 3% for the control diet and to adjust total added lipid content of the other diets to 3%. Average initial body weight was 57.39 ± 0.25 g/fish. Six experimental diets were fed twice daily to four replicate aquaria for six weeks. At that time, fish were group weighed for determination of weight gain and feed conversion. Fillets of six fish per aquarium were recovered and stored at − 80 °C for moisture and total lipid analyses, fatty acid analysis, and sensory evaluation. Results showed feed consumption and feed conversion did not differ ( P > 0.05). Significantly ( P < 0.05) greater body weight gains were observed only for fish fed the diets with two combinations of CLA and 1.5% fish oil compared to fish fed the diet containing 0.5% CLA and corn oil. Fillet n − 3 HUFA levels were significantly ( P < 0.05) elevated for fish fed diets containing fish oil when compared to n − 3 HUFA of fillets of fish fed diets containing either corn oil or CLA and corn oil. Similarly, fillets from fish fed diets amended with CLA contained substantial amounts of CLA of up to 6.4% of total lipids. Fillets from fish fed corn oil or fish oil diets had no CLA. Taste panel evaluation indicated that fillets containing n − 3 HUFA and CLA were essentially without fishy off-flavor and had excellent sensory qualities. Catfish fillets produced by amending diets with sources of n − 3 HUFA and CLA at the levels used in this study would contain elevated levels of these nutraceuticals and could be an important human food source for these healthful fatty acids.

Use of the p,p'-DDD: p,p'-DDE Concentration Ratio to Trace Contaminant Migration from a Hazardous Waste Site

For approximately 50 years, beginning in the 1920s, hazardous wastes were disposed in an 11-hectare area of the Marine Corps Base (MCB) Quantico, Virginia, USA known as the Old Landfill. Polychlorinated biphenyls (PCBs) and DDT compounds were the primary contaminants of concern. These contaminants migrated into the sediments of a 78-hectare area of the Potomac River, the Quantico Embayment. Fish tissue contamination resulted in the MCB posting signs along the embayment shoreline warning fishermen to avoid consumption. In this paper, we interpret total PCB (t-PCBs) and total DDT (t-DDT, sum of six DDT, DDD, and DDE isomers) data from monitoring studies. We use the ratio of p,p'-DDD to p,p'-DDE concentrations as a tracer to distinguish site-related from regional contamination. The median DDD/DDE ratio in Quantico Embayment sediments (3.5) was significantly higher than the median ratio (0.71) in sediments from nearby Powells Creek, used as a reference area. In general, t-PCBs and t-DDT concentrations were significantly higher in killifish (Fundulus diaphanus) and carp (Cyprinus carpio) from the Quantico Embayment compared with Powells Creek. For both species, Quantico Embayment fish had mean or median DDD/DDE ratios greater than one. Median ratios were significantly higher in Quantico Embayment (4.6) than Powells Creek (0.28) whole body carp. In contrast, t-PCBs and t-DDT in channel catfish (Ictalurus punctatus) fillets were similar in Quantico Embayment and Powells Creek collections, with median ratios of 0.34 and 0.26, respectively. Differences between species may be attributable to movement (carp and killifish being more localized) and feeding patterns (carp ingesting sediment while feeding). We recommend that environmental scientists use this ratio when investigating sites with DDT contamination.

Eating Ivy

This essay is both celebration and portrait of the late Barton Rouse and his influential career as chef at the Terrace Club of Princeton University during the writer's undergraduate career. In the late 1980s and early 1990's Barton Rouse transformed a dilapidated building into a culinary mecca. He planned inventive daily menus (chrysanthemum soup; broiled tuna with morel sauce; White Trash Night) and hosted extravagant special events: an anti-Valentine's day dinner, for instance, which featured Blackened Rib Steaks and Catfish Fillets, Black fettuccine with sour cream and lox sauce and red and black caviar, bleeding hearts of beet salad, brandied cherry ambrosia, and mocha espresso cheesecake. The man and his food broke boundaries between high culture and low, good taste and bad, east and west, rural and urban, adult and child. In the process of cooking for his members, Rouse taught hundreds of young people how to eat, but also that cooking was a labor of love and a genuine aesthetic pursuit. His humor, whimsy, and inventive extravagance left a legacy which links inextricably food and politics to our fundamental way of being in the world.

Prevalence and Typing of Listeria monocytogenes in Raw Catfish Fillets

Raw channel catfish fillets collected from three processing plants during four time periods were tested for the presence of Listeria species. Listeria monocytogenes was the predominant Listeria species found in these catfish fillets, with 25 to 47% prevalence. Other Listeria species, such as L. welshimeri, L. innocua, L. ivanovii, L. grayi, and L. seeligeri, were also found. L. monocytogenes isolates were further fingerprinted by a repetitive element PCR. Forty distinctive electrophoretic types (ETs) and three genetic clusters were determined by Dice coefficient analysis and UPGMA (unweighted pair group method using arithmetic averages). Twenty of 40 ETs were represented by a single isolate, and the other 20 ETs were represented by 2 to 11 isolates. Thirty-five ETs, represented by 76 isolates, were found in processing plant A, B, or C and designated plant-specific types. The remaining five ETs, represented by 21 isolates, were found in multiple plants and designated nonplant-specific types. In addition, 10 ETs from 52 isolates were found repeatedly during different seasons. Plant-specific and nonplant-specific L. monocytogenes coexisted in processed catfish fillets. Some isolates were persistently found in processed fillets, suggesting that either the current sanitation procedures used by these plants are inadequate or that these isolates originated from the natural habitats of the catfish. The results also suggest that the repetitive element PCR is a useful tool for differentiating L. monocytogenes subtypes and can be used for tracing the source of a contamination.

Detection of off-flavour in channel catfish (Ictalurus punctatus Rafinesque) fillets by trained dogs

Richard A Shelby, Lawrence J Myers, Kevin K Schrader & Phillip H Klesius U. S. Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Laboratory, Auburn, AL 36830, USA Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, AL, USA U. S. Department of Agriculture, Agricultural Research Service, Natural Products Utilization Research Unit, University, MS, USA

Analysis of U.S. Catfish Fillet Market Share Using a Flexible Logistic Model

This paper forecasts market share for U.S. frozen, farm-raised catfish fillets using alternative logit formulations. Results suggest the log inverse power transformation (IPT) performs better than the simple logit and IPT logit models, and had the smallest percentage errors for out-of-sample forecast. Estimates from the log-IPT model indicated higher price premiums of U.S. catfish fillets negatively affected market shares. As domestic fillet wholesale price levels increased relative to imported fillet price, buyers would substitute domestic catfish with imported catfish, assuming undifferentiated products. Catfish is found to be a necessity with a negative relationship between income and shares, equating sales values to consumer expenditures. Total market demand for catfish appears relatively stable following changes in the economy, typical of necessities. It suggests caution in price setting policies. A pricing strategy based on higher sales volumes to address the declining market share situation could be an effective policy measure for optimal long-run sustainability and profitability of the industry.