Effects of Potassium Lactate and Acetate on Listeria monocytogenes Inhibition,Physicochemical and Sensory Properties of Smoked Catfish Fillets

The objective of this study was to evaluate the effects of liquid and wood smoking with a potassium lactate (PL) and acetate (PA) combination on the quality and inhibition of L. monocytogenes growth in ready-to-eat (RTE) smoked catfish fillets. Catfish fillets were tumbled with PL and PA, and treated with no smoke (NS), wood smoke (WS), liquid smoke 1 (LS1), and liquid smoke 2 (LS2). Wood smoke with antimicrobials (WSWA) showed greater inhibition (p < 0.05) of L. monocytogenes growth than other treatments with the exception of the LS1 treatment with antimicrobials. Consumers preferred (p < 0.05) smoked catfish fillets treated with WS to LS1 with respect to appearance, odor, flavor, texture, and overall acceptability. In conclusion, the use of PL and PA did not have a negative impact on the quality and sensory properties of smoked catfish fillets but had a synergistic effect with wood smoke constituents that inhibited the growth of L. monocytogenes.     

Microbial Quality,Safety, and Sensory Acceptability of X-ray Treated Fresh Channel Catfish Fillets

This study was designed to determine if treatment with low dose X‐ray irradiation changes microbial quality (microbial load), safety (Listeria monocytogenes incidence), and sensory characteristics (aroma, appearance, and texture) of fresh aquacultured Channel catfish (Ictalurus punctatus) fillets during refrigerated storage. Fillets were treated to 0, 0.5, 1.0, and 1.5 kGy using an X‐ray irradiator and stored at 3°C for 17 days. Fillet aerobic plate count (APC), psychrotrophic plate count (PPC), total coliform count (TCC), and L. monocytogenes incidence were measured every 4 days during storage. A Difference-From-Control test was used to measure aroma, appearance, and texture. Fillet microbial counts were significantly different (p < 0.05) with time, irradiation dose, and the interaction of these two treatments. As expected, APC, PPC, and TCC increased as storage time increased. Overall L. monocytogenes incidence was 40%, 27%, 0%, and 7% at 0, 0.5, 1.0, and 1.5 kGy, respectively. Aroma of irradiated and non‐irradiated catfish fillets was significantly different, with greater aroma differences recorded as storage time increased due to progressional spoilage of the untreated controls. However, there were no significant aroma differences noted among the different irradiation doses. Neither appearance nor texture was significantly different between any treatments throughout testing. This study indicated that exposure to low dose X-ray irradiation improved the microbial quality and safety of fresh catfish fillets without affecting sensory acceptability at time of purchase.     

Effect of Different Thawing Methods and Multiple Freeze-Thaw Cycles on the Quality of Common Carp (Cyprinus carpio)

The effect of different thawing methods—running water, microwave, slack water (25°C), air (25°C), and refrigerator (4°C)—and multiple freeze-thaw cycles (0, 1, 3, and 5) on the quality of common carp were investigated. Microwave thawing showed the lowest score for sensory assessment and the highest cooking loss (p < 0.05), while 4°C refrigerator thawing showed less thawing loss and cooking loss but required the longest thawing time. Ca²⁺-ATPase activity and sulfhydryl content of air thawing were lower (p < 0.05), while no significant differences were observed among other thawing methods. Water loss and the thiobarbituric acid reactive substances (TBARS) value increased (p < 0.05) when freeze-thaw cycles increased. The sensory scores and hardness decreased significantly when the freeze-thaw cycles increased (p < 0.05). A significant decrease (p < 0.05) was observed in salt-extractable protein content after five freeze-thaw cycles. Different thawing methods affected the quality of common carp. Frozen common carp subjected to freeze-thaw cycles resulted in accelerated lipid and protein oxidation and caused mechanical damage to muscle tissues.     

Effect of the UV-C Radiation on Shelf Life of Vacuum-Packed Refrigerated Pirarucu (Arapaima gigas) Fillets

The effect of Ultraviolet radiation type C (UV-C) radiation (0.100 ± 0.010 J/cm²) on shelf life of Arapaima gigas fillets stored at 4 ± 1°C for 18 days was investigated. The samples were analyzed for total aerobic mesophilic bacteria (TAMB) counts; total aerobic psychrotrophic bacteria (TAPB) counts; Enterobacteriaceae; purge loss; pH; lipid oxidation; total volatile bases (TVB-N); ammonia; biogenic amines (BAs); and L*, a*, and b* values. UV-C radiation increased (P < 0.05) the generation time of all bacterial groups evaluated, increasing the shelf life by 2 days. UV-C-treated fillets showed lower (P < 0.05) L* values, purge loss, pH, TVB-N, ammonia, and BAs levels than their control counterparts throughout the storage period. Moreover, UV-C treatment did not result (P > 0.05) in detrimental effects on lipid oxidation or a* and b* values. UV-C at 0.100 J/cm² demonstrated a good potential for use in A. gigas fillets and, therefore, it could be applied at industrial scale.     

Sensory and Physicochemical Properties of Smoked Catfish Sausages

The objective of this study was to determine the physiochemical characteristics and sensory quality of smoked, coarse-ground catfish sausages and catfish frankfurters by using 100% fillets, 75% fillets with 25% nuggets, and 50% fillets with 50% nuggets (the proportions of fillets and nuggets equaled 100% for each of the three formulations). Pork fat was added to each formulation to bring the final fat content to 20%. Lightness (L*) decreased (p < 0.05) as percentage of nuggets increased in frankfurter and coarse-ground sausages. Based on texture profile analysis results, coarse-ground sausages showed lower (p < 0.05) springiness, cohesiveness, hardness, gumminess, and chewiness than frankfurters. Attributes of aroma, flavor, and texture were not affected (p > 0.05) by catfish fillet percentage but were affected (p < 0.05) by sausage type. In addition, no differences existed (p > 0.05) in consumer acceptability among frankfurter samples, with all samples receiving average scores between “like moderately” and “like very much.” Results indicate that catfish fillets and nuggets could be used to produce catfish frankfurters with acceptable sensory properties.     

Effect of Freeze-Chilled Treatment on Flavor of Grass Carp (Ctenopharyngodon idellus) Fillets and Soups During Short-Term Storage

ABSTRACT

In order to evaluate the effect of chilled (T1), frozen (T2), and freeze-chilled (T3) treatment on the flavor of grass carp fillets and soups, adenosine triphosphate (ATP)-related compounds, umami-taste amino acids (UTAA), thiobarbituric acid (TBA), peroxide value (PV), and soup sensory score were analyzed. Results showed that the sum of ATP, ADP, and AMP contents in T2 fillets were significantly higher (p < 0.05) than others, but the sum of hypoxanthine riboside (HxR) and hypoxanthine (Hx) contents for T2 fillets and soups were significantly lower (p < 0.05) than others during storage. The T3 fillets and soups had lower inosine 5-monophosphate (IMP) contents than T1 after Day 2, but higher UTAA contents than T1 during storage. The T3 fillets had the highest TBA and PV values among the three groups during storage. According to the total aerobic counts, K value, and sensory score, all the fillets and soups kept good quality during storage. Therefore, freeze-chilled treatment not only can extend fish shelf life but also retain excellent fish flavor.     

Effect of Traditional and Liquid Smoke on the Quality of Sea Catfish Sausages (Sciades herzbergii,Bloch, 1794)

ABSTRACT

Smoking is a technique used to improve the sensory attributes and increase the shelf life of fish. The objective of the present study was to evaluate the nutritional, physicochemical, microbiological, and sensory characteristics of sausages made with sea catfish (Sciades herzbergii) fillets subjected to the traditional and liquid smoking processes. The traditionally smoked sausages showed lower (p < .05) moisture content and higher protein, fat, and mineral levels, higher weight loss during processing, higher pH, higher a* (red intensity), and lower L* (luminosity) values. The percentage of shrinkage, water holding capacity, water activity, hardness, cohesiveness, and elasticity were not influenced (p > .05) by the smoking methods tested. The microbial counts of both treatments were in compliance with the current Brazilian legislation. The sensory acceptance of the liquid smoked sausages was higher (p < .05) when compared to the traditionally smoked sausages for the attributes of color, aroma, texture, flavor, and overall acceptance, with scores ranging from 6 (liked slightly) to 7 (liked moderately). Between the two smoking methods tested, liquid smoking presented better sensory acceptance, easier execution, greater process control, and less environmental impact; thus, it is a viable alternative to the traditional smoking of sea catfish (Sciades herzbergii) sausages.     

The Influence of Different Dietary Carbohydrate to Lipid Ratios on Some Qualitative Characteristics of Fillets of Beluga (Huso huso) During Refrigeration

In this study, juvenile beluga (Huso huso) were fed diets containing different carbohydrate to lipid ratios for 5 months. At the end of the culture period, proximate compositions of the fish carcasses (moisture, protein, fat, and ash) were measured. Then, qualitative changes in the fishes were evaluated during 24-days refrigeration (4°C), along with changes in their total volatile bases nitrogen (TVN), thiobarbituric acid (TBA), free fatty acids (FFA), pH, and muscle texture profile analysis. The results of proximate analysis of the carcasses showed that moisture, protein, and ash of the carcasses increased significantly (p < 0.05) with higher carbohydrate to lipid ratio, but fat content of the carcasses decreased significantly (p < 0.05). Further, during refrigeration, TVN, TBA, and FFA increased significantly in all the samples (p < 0.05), but these changes did not follow the same pattern in all the treatments. Tissue hardness decreased during preservation. Although pH changes in the fillets were low, they were significant and without a clear-cut pattern. The results showed that use of different carbohydrate to lipid ratios in diet does not lead to clear-cut changes in qualitative characteristics of beluga fillets during refrigeration.     

Effects of Oil-in-Water Nanoemulsion Based on Sunflower Oil on the Quality of Farmed Sea Bass and Gilthead Sea Bream Stored at Chilled Temperature (2 ± 2°C)

The influence of oil-in-water nanoemulsion on the sensory, chemical, and microbiological qualities of sea bream and sea bass fillets stored at 2 ± 2°C was investigated. The results showed that the use of nanoemulsion extended the shelf life of fish one or two days when compared with the control. Treatment with nanoemulsion significantly (p < 0.05) decreased the values of chemical parameters throughout the storage period. Bacterial growth was inhibited by the use of nanoemulsion. Nanoemulsion had an inhibitory effect on protein denaturation during refrigerated storage and microwave cooking. Based on the results, it can be concluded that sunflower oil-based nanoemulsion extended the shelf life and improved the quality of both sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) fillets during storage.     

Suspending Mammalian LHRHa‐injected Channel Catfish,Ictalurus punctatus,in Individual Soft Mesh Bags Reduces Stress and Improves Reproductive Performance

Hormone‐induced spawning of channel catfish held communally in tanks is a reliable method to produce channel catfish, Ictalurus punctatus ♀ × blue catfish, Ictalurus furcatus ♂, F₁ hybrid catfish fry. However, mature catfish are crowded, and repeatedly handled during the process of induced ovulation. Repeated handling of gravid females is stressful and may impair ovulation, egg quality, and reproductive performance. Three trials were conducted to evaluate the effects of two methods of confining post‐hormone‐injected female channel catfish on stress response (cortisol concentrations) and reproductive performance: fish were either held individually while suspended in soft, nylon‐mesh bags or communally in a concrete tank. Percent of females ovulated to hormone treatment, relative fecundity, percent egg viability, and latency of channel catfish did not differ for fish in the two treatments. However, percent hatch and fry/kg of females was higher (P < 0.05) for fish held in bags that for fish held communally in tanks. Mean plasma cortisol response immediately prior to the first hormone injection (0 h) did not differ among fish groups in the two treatments. However, mean plasma cortisol concentrations were significantly lower (P < 0.05) for fish in the bag treatment at 16 and 36 h compared to fish held communally in tanks. Plasma estradiol levels (measure of oocyte maturation) were assessed at 0, 16, and 36 h after hormone injection; concentrations were (P < 0.05) higher at 16 h compared to 0 and 36 h; however, estradiol concentrations did not differ for fish held in the two treatments (P > 0.05). Suspending hormone‐injected broodfish individually in soft bags reduced stress response, improved egg hatching rate, and increased hybrid fry produced per kg weight of female broodfish. Using this simple technology, farmers can improve the efficiency of hatcheries producing hybrid catfish fry.     

Changes in Physicochemical and Protein Structural Properties of Common Carp (Cyprinus carpio) Muscle Subjected to Different Freeze–Thaw Cycles

The present study investigated physicochemical and protein structural changes in common carp muscle subjected to different freeze–thaw (FT) cycles. With increasing number of FT cycles, the thawing losses, cooking loss, L*- and b*-value increased, and shear forces and a*-value decreased (p < 0.05). The study showed that multiple FT processes were detrimental to color and water-holding capacity of carp muscle. The increases in thiobarbituric acid reactive substances and carbonyl content with concomitant decrease in sulfhydryl group content (p < 0.05) showed that multiple FT caused carp lipid and protein oxidation, especially for the carp muscle subjected to five freeze–thaw cycles. Myofibrillar protein isolated from FT muscle showed an increased hydrophobicity, reduced ATPase activity, and enhanced susceptibility to thermal aggregation (p < 0.05). These protein structural changes resulted in major losses in muscle quality. Overall, the disrupted protein structure, together with the denaturation of myofibrillar protein induced by FT, was most likely associated with lowered muscle quality.     

Feeding Channel Catfish, Ictalurus punctatus, Diets Amended with Refined Marine Fish Oil Elevates Omega-3 Highly Unsaturated Fatty Acids in Fillets

Channel catfish, Ictalurus punctatus, 88.4 ± 2.6 g/fish, were fed a basal diet amended with 4% of three processed menhaden, Brevoortia tyrannus, oils. These were compared with basal diets amended with 4% corn oil or 4% canola oil. Three replicate aquaria of nine fish each were fed assigned diets twice daily. At 6 wk, fish were group weighed, fillets were collected for sensory evaluation, fatty acid analysis by gas chromatography (GC). In a second study, catfish, 118.8 ± 3.2 g/fish, were stocked into fifteen 0.04‐ha earthen ponds and fed once daily for 16 wk one of four diets containing 2 or 4% of either catfish offal oil or refined (RF) menhaden oil. At harvest, fillets were saved for sensory evaluation and fatty acid analysis. Results showed no significant (P > 0.05) differences among treatments for aquarium study and pond study variables such as weight gain, fillet proximate analysis, or pond production. GC analysis showed that levels of omega‐3 (n‐3) highly unsaturated fatty acids (HUFA) in fillet lipid were significantly (P < 0.05) elevated for fish fed menhaden oil diets. Sensory evaluation revealed that fillets from fish fed RF menhaden oil had satisfactory flavor and could be a source of n‐3 HUFA for humans.     

Growth and health performance of African catfish Clarias gariepinus (Burchell 1822) juvenile fed with graded levels of biofloc meal

The objective of the study was to evaluate the utilization of biofloc meal as a feed ingredient in enhancing the growth and health status of African catfish (Clarias gariepinus) juvenile. The study consisted of two experiments, that is digestibility and growth experiments. The digestibility of two biofloc meals produced with two different carbon sources, that is tapioca and molasses, were assessed in the digestibility experiment. Whereas the effect of four dietary treatments with different levels of biofloc meal, that is 0%, 5%, 10% and 20%, on the fish growth performance, feed utilization, immuno‐haematological response, antioxidant status and robustness against environmental stress were evaluated in the growth experiment. The results showed that the digestibility of dry matter, protein, lipid and phosphorus of biofloc grown using molasses as the carbon source were remarkably higher than that grown using tapioca (p < 0.05). The inclusion of biofloc meal in the diets at 10% and 20% resulted in higher feed intake, fish growth and final biomass and protein efficiency ratio, and lower feed conversion ratio (p < 0.05). Furthermore, the red blood cells counts, phagocytic, lysozyme activities and antioxidative capacity were significantly enhanced in the fish provided with diet containing 20% biofloc meal (p < 0.05).The fish survival following salinity stress test was higher in the treatments with biofloc meal at 10% and 20% inclusion levels. In conclusion, dietary inclusion of biofloc meal could improve the growth performance and health status of African catfish juvenile and an inclusion level of 20% could be recommended.     

Color and Carotenoid Content Changes of Yellow Discolored Channel Catfish,Ictalurus punctatus,Fillets during Refrigerated Storage

Yellow pigment deposition is a quality defect associated with channel catfish fillets. This study evaluated the relationship between fillet color and carotenoid contents as well as the effect of refrigerated storage on the color and carotenoid content of discolored catfish fillets. The color and carotenoid content of the yellow fillets were analyzed using the L, a, b‐color system and high performance liquid chromatography analysis, respectively. A strong linear relationship between visual yellowness (i.e., the b‐values) of fresh catfish fillets and the sum of three major carotenoid contents was observed. Yellow discolored catfish fillets became darker and more yellow during 12 d of refrigerated storage. However, the total carotenoid content of yellow fillets decreased or remained unchanged during storage. Results suggest that while the yellow discoloration of fresh catfish fillets is related to carotenoid contents, the intensification of the discoloration during storage appears to be related to another chemical phenomenon.     

Influence of Chitosan Nanocomposite and Rosemary (Rosmarinus officinalis L.) Extract Coating on Quality of Huso huso Fillet Inoculated with Listeria monocytogenes During Refrigerated Storage

This study aimed to evaluate the antilisterial and antioxidative effects of chitosan nanocomposites and rosemary extract coating on the fillet of Huso huso inoculated with Listeria monocytogenes during refrigerated storage (4°C). Fish fillets were subjected as control (without coating), 0.5% rosemary extract (RE), 1% chitosan (CS), and combination of chitosan and rosemary extract as chitosan nanocomposite (CS/RE). Then, samples were inoculated with L. monocytogenes. Subsequently, the chemical parameters (total volatile basic nitrogen (TVB-N), peroxide value (PV), pH, and thiobarbituric acid (TBA)) and antilisterial effects of coatings were monitored during 16 days of storage at 4°C. According to the results, CS/RE demonstrated a significant (p < 0.05) ability to inhibit the growth of L. monocytogenes from 4.14 log cfu/g to 2.23 log cfu/g at the end of the storage period, followed by CT and RET treatments, respectively, compared to the control. Even though samples coated with CS/RE had the lowest pH and TVB-N values (p < 0.05), this coating was not able to pause the protein denaturation after 8 days of storage (p > 0.05) compared to the other treatments. On the other hand, CS/RE coating retarded lipid oxidation by decreasing PV and TBA production in the samples compared to the control up to the end of refrigerated storage (p < 0.05).     

Increased dietary protein‐to‐lipid ratio improves survival during naturally occurring pancreas disease in Atlantic salmon,Salmo salar L.

This study demonstrated that increased dietary protein‐to‐lipid ratio (P/L‐ratio) improved survival of farmed Atlantic salmon naturally affected by pancreas disease (PD). In addition to diet, body weight (BW) and delousing mortality prior to the PD outbreak also contributed significantly (p < 0.05) to explain the observed variation in PD‐associated mortality. Subsequent to the PD outbreak, large amount of fish failed to grow and caused thin fish with poor condition (runts). At the end of the trial, significantly (p < 0.05) lower amounts of runt fish and increased amount of superior graded fish where detected among fish fed increased P/L‐ratio and within the fish with the largest BWs prior to PD. Diet, BW and delousing mortality contributed significantly (p < 0.05) to explain the variation in the amount of superior graded fish, whereas BW and diet explained the variation in the amount of runt fish. A significant (p < 0.01) negative linear relationship was observed between the amount of superior graded fish and the total mortality, whereas a positive linear relationship was detected between percentage of fillets with melanin and the total mortality. Thus, increased dietary P/L‐ratio seem to reduce the mortality and impaired slaughter quality associated with PD.     

POLYCULTURE OF CHANNEL CATFISH (Ictalurus punctatus) WITH ALL-MALE TILAPIA HYBRID

Channel catfish (Ictalurus punctatus) (x? = 0.8 g) and all-male hybrid tilapia fingerlings (Sarotherodon mossambica ♂ × S. hornorum ♀) (x? = 35.0 g) were stocked in 0.04 ha replicated ponds in Baton Rouge, Louisiana, in March and July 1981, respectively. The ponds were stocked at densities of 11,110 catfish per ha, 11,110 catfish with 5,550 tilapia per ha, 7,400 catfish per ha, and 7,400 catfish with 3,700 tilapia per ha. The fish were fed daily at 4% of estimated catfish biomass and were harvested in November 1981. There were no differences in dissolved oxygen or water temperature among the four culture systems (P > 0.05). The presence of tilapia, however, significantly increased water turbidity, pH and chlorophyll a concentrations (P < 0.05). Tilapia did not improve water quality and may have deteriorated it. Tilapia did not affect channel catfish growth or production (P > 0.05), but the presence of tilapia did significantly increase total fish yield (P < 0.05) by 13.5 and 32.2% at low and high catfish densities, respectively. Channel catfish and tilapia averaged 390 and 245 g at harvest, respectively. Overall catfish survival averaged 61%. Tilapia survival was 72% and 61% at low and high densities, respectively.     

Biological Feasibility and Costs of Production of Large Channel Catfish,Ictalurus punctatus,for a Specialty Product Market

Restaurant patrons, particularly in upscale locations, increasingly prefer entrées developed from portions cut from fillets larger than those currently sold by the US catfish, Ictalurus punctatus, industry. A production study evaluated the feasibility of producing the necessary size (1.6 kg) of catfish. Twelve 0.1‐ha earthen ponds were stocked with 0.363‐kg channel catfish at 2500 (low); 5000 (medium); or 7500 (high) fish/ha, with four replicates. Mean individual weight at harvest exceeded the mean target weight (1.6 kg) at the two lower densities, and the minimum target weight (1.36 kg) at the highest density. Percentages of fish (by weight) that did not meet the minimum weight required were: 1, 5, and 18%, in the low, medium, and high density treatments, respectively. Yields were significantly greater at higher densities (P < 0.05). Costs of production at the two higher densities were 4 to 7% higher than in the traditional multiple‐batch system, but increased to 51% at the lowest density. Results demonstrated the biological feasibility of producing channel catfish of a mean weight of 1.6 kg. Economic feasibility depends on (1) the price premium paid and (2) development of a market for fish sizes between current acceptable maximum sizes accepted and 1.36 kg.     

Relationship between Lipid Oxidation,Protein Function Properties,and Freshness Changes of Salt-Treated Blunt-Snout Bream (Megalobrama amblycephala) Fillets Stored at 4°C

The aim of this study was to investigate the relationship between lipid oxidation, protein function properties, and freshness changes of blunt-snout bream (Megalobrama amblycephala) fillets treated with 2% and 4% salt during storage at 4°C. Salting with 2% and 4% salt could delay quality deterioration and protein denaturation, thus improving sensory attributes to some extent. But, 4% salt promoted lipid oxidation of blunt-snout bream fillets. There is a significant correlation (p < 0.05) between freshness indexes and lipid oxidation or protein function properties (total SH content, Ca²⁺-ATPase activity). Salting with 2% salt is an ideal treatment to control the quality of blunt-snout bream fillets stored at 4°C.     

Current status of farming practices of striped catfish, Pangasianodon hypophthalmus in the Mekong Delta, Vietnam

Aquaculture of catfish, Pangasianodon hypophthalmus (Sauvage), locally known as “ca tra”, and commonly referred to as striped catfish, river catfish and sutchi catfish, in Vietnam, having recorded a production of 683,000 tonnes in 2007, valued at about 645 million US$ is one of the largest single species based farming system, restricted to a small geographical area, in the world. The product is almost totally exported to over 100 countries as frozen fillets, as an acceptable alternative to white fish. Catfish is farmed mostly in earthen ponds, up to 4 m deep, in nine provinces in the Mekong Delta in South Vietnam. The results of the grow-out system of catfish farming in the Mekong Delta from a survey of 89 farms are presented. The farm size ranged from 0.2 to 30 ha with a mean of 4.09 ha. The frequency distribution of the yield in tonne/ha/crop and tonne/ML/crop corresponded to a normal distribution curve, where 75% of the farms yielded 300 tonnes/ha/crop or more. It was found that the yield per crop was significantly correlated (p < 0.05) to stocking density, pond depth and volume but not to pond surface area. Yields per crop was significantly different (p < 0.05) between upper and lower provinces of the Mekong Delta and water source (river versus channels), amongst others. It was evident that diseases and/or symptoms were observed to occur mostly in accordance with the onset of rains. In this paper the history of the catfish farming in the Mekong Delta is briefly traced, and current harvesting and marketing procedures as well as pertinent social elements of the farming community are dealt with.