Fillet Color Research Articles

Correlation of Mullet (Mugil cephalus) Fillet Color Changes with Chemical and Sensory Attributes during Storage at 0°C

ABSTRACT The main objective of this study was to assess the freshness of striped mullet (Mugil cephalus) fillets stored at 0°C by evaluating color changes using a machine vision system and correlating this to chemical and sensory attributes. The mean L*, a*, b* values from the entire area of the fillet surface were calculated by image analysis. These values for the skin side of fillets did not show a significant change during storage. The increase in a* value and the decrease in b* value were significant at Day 6 for the meat side of fillets. According to peroxide value (PV) (0.98 ± 0.071 mmol CPO/kg fish) and thiobarbituric acid reactive substances (TBARS) (6.38 ± 1.06 mg MDA/kg fish) values, mullet fillets were not acceptable for consumption at Day 6. However, according to sensory evaluation, fillets were rejected at Day 4, with an overall quality score of 5.12 ± 3.80 out of 15. Chemical analysis, particularly TBARS and PV, significantly correlated with color changes in the meat side of mullet fillet. The a* and b* values for the meat side are good indicators of the quality deterioration in mullet fillets stored at 0°C. Machine vision can be used as an alternative and promising method to evaluate the freshness of mullet fillets.

Supplementation of tuna hydrolysate and insect larvae improves fishmeal replacement efficacy of poultry by-product in Lates calcarifer (Bloch, 1790) juveniles

The effects of feeding different levels of poultry by-product meal (PBM) replacing fishmeal (FM) protein, supplemented with tuna hydrolysate (TH) and Hermetia illucens (HI) larvae, on the growth, fillet quality, histological traits, immune status, oxidative biomarker levels and gut microbiota of juvenile barramundi, Lates calcarifer were investigated for six weeks. Barramundi were fed four isonitrogenous and isolipidic diets in which a FM based diet was used as the Control diet (Diet1) and compared with other non-FM diets containing 80%, 85% and 90% PBM along with the concurrent supplementation of 5% and/or 10% TH and HI larvae meal. These treatment diets were designated as 80PBM10TH+10HI (Diet2), 85PBM5TH+10HI (Diet3) and 90PBM5TH+5HI (Diet4). The growth and condition factor of fish fed 80PBM10TH+10HI and 85PBM5TH+10HI were significantly higher than the Control. Total saturated, monounsaturated and polyunsaturated fatty acid retention in the fish muscle increased in fish fed PBM-based diets, supplemented with TH and HI larvae meal, with no adverse effect on post-harvest characteristics such as texture and colour of fish fillets. Improvement in serum total bilirubin and total protein content was found in all fish fed TH and HI larvae supplemented PBM. Similarly, immune response showed a significant increase in fish fed non-FM test diets than the Control. In the distal intestine, supplementation of any quantities of TH and HI larvae to PBM led to an increase in the microvilli density and neutral mucins while the number of goblet cells in the skin were unchanged. Liver, kidney, and spleen histology demonstrated a normal structure with no obvious changes in response to all test diets. Bacterial diversity increased in fish fed Diets 2 and 3 with a high abundance of Proteobacteria in Diets 1 and 4 and Firmicutes in Diets 2 and 3. The fish on test diets showed a lower abundance of genus Vibrio. Fish fed TH and HI larvae supplemented PBM diets showed lower infection rate to V. harveyi than the Control. Collectively, concurrent supplementation of TH and HI larvae could improve the quality of PBM diets with positive effects on growth, fillet quality, intestinal health, immunity, and disease resistance.

Flesh quality recovery in female rainbow trout (Oncorhynchus mykiss) after spawning

In fish rearing industry, sexual maturation results in loss of profit or at least in a delay to valorize spawning fish. Indeed, many edible fish display poor fillet quality after sexual maturation and as such cannot be processed immediately after spawning. So, a post-spawning rearing period may allow the recovering of an acceptable fillet quality. So far, flesh quality restoration after spawning has received little attention. In the present study, the evolution of technological and organoleptic qualities was investigated in diploid autumnal strain female rainbow trout (24 months of age) after spawning. Immediately after spawning, nine groups of trout (n = 25) from the same cohort were placed separately into circular tanks and fed ad libitum. Fish were then sampled at 0, 1, 2, 4, 8, 13, 16, 24, and 33 weeks after spawning (PS0, PS1, PS2, PS4, PS8, PS13, PS16, PS24, and PS33). Immature (no egg produced) female trout from the same cohort were also sampled as controls at the beginning (C0) and at the end (C33) of the experiment. Immediately after spawning, PS0 trout showed a significantly lower raw fillet yield than control (C0). Furthermore, raw fillet from these trout was less colored (lower redness a*) and presented higher lightness L* value than raw fillet from C0 trout while their fillet mechanical resistance was similar. Raw fillet yield increased after the 16th week post-spawning. The fillet lightness steadily decreased from the 4th week to the 24th week post-spawning and did not change afterwards, whereas fillet redness increased from the 8th week to the 24th week after spawning. Fillet mechanical resistance declined progressively after spawning with a significant change from the 13th week. Concerning the smoked fillet, the smoking yield of PS0 trout was significantly lower than that of C0 trout. Thereafter the smoking yield of post-spawning trout slowly increased until reaching a significantly higher value at the 24th week. The evolution of smoked fillet color and mechanical resistance after spawning was similar to that of raw fillet. At the end of the experiment, most quality parameters of PS33 trout fillet were similar to those of C33 trout. We discuss the post-spawning quality parameters recovery in three sequential phases. On the whole, our study reports that the technological and organoleptic properties of the flesh were recovered in female trout 24 weeks after spawning (≈1400 °C.day).

Synergistic effect of kojic acid and tea polyphenols on bacterial inhibition and quality maintenance of refrigerated sea bass (Lateolabrax japonicus) fillets

Fresh fish are highly perishable because their high content of protein and unsaturated fatty acids are easily oxidized and/or degraded under the influence of bacteria and the external environment. In this study, four natural preservatives (phenyllactic acid, kojic acid, tea polyphenols and thymol) were initially screened for antimicrobial activity against spoilage bacteria commonly found in fish by in vitro antibacterial tests. The results suggested that kojic acid (KA) and tea polyphenols (TP) exhibited a strong synergistic antibacterial effect against spoilage bacteria. Hence, the effects of KA and/or TP on the preservation of refrigerated sea bass (Lateolabrax japonicus) fillets after soaking treatments were determined. Changes in physicochemical parameters, indexes of fish freshness and microbial enumeration were examined. KA, TP and KA-TP treatments were effective in inhibiting bacterial growth and delaying lipid oxidation in fish flesh, resulting in lower TVB-N and TBARS than the control. Meanwhile, the freshness and physical qualities (color and texture) of fish fillets were also stabilized by the three treatments. Moreover, the KA-TP treatment showed the best effect on refrigerated fish preservation among the three treatments and extended the shelf-life by 5–6 days, suggesting that KA-TP have the potential to become a compound preservative for aquatic products.

Black soldier fly (Hermetia illucens) pre-pupae larvae meal in diets for European seabass (Dicentrarchus labrax) juveniles: Effects on liver oxidative status and fillet quality traits during shelf-life

A study was undertaken to evaluate the effect of dietary fishmeal (FM) replacement with Hermetia illucens prepupae larvae meal (HM) on oxidative stress indicators and fillet quality traits during shelf-life of European seabass (Dicentrarchus labrax) juveniles. HM was used replace 0%, 15%, 30% and 45% of dietary FM, corresponding to an inclusion level of 0%, 6.5%, 13%, and 19.5% of HM. After a feeding period of 62 days, fillet quality traits were analysed immediately after sampling (T0) and after three days of storage at +2/4 °C (T3). At the end of the feeding trial, hepatic lipid peroxidation and activities of superoxide dismutase decreased, catalase activity decreased at intermediary HM inclusion levels, while glutathione peroxidase and glutathione reductase activities were unaffected with the dietary inclusion of HM. Irrespectively of the diet, storage time did not affect the skin and fillet (dorsal and ventral regions) colour, while fillet pH was higher at the highest dietary HM inclusion level. Biometry traits, slaughter yield, fillet proximate composition, and liver fatty acid (FA) profile were not affected by dietary treatment. Fillet fatty acid profile was also unaffected by diet or storage time, except total C18-FA that decreased at the two intermediary levels of HM inclusion, n-6 PUFA that was higher in fillets from fish fed the HM-based diets, and total n-3 PUFA that decreased with the increase of dietary HM level at T3. The n-3/n-6 ratio was not affected by the diets but decreased with the refrigeration time. Docosapentaenoic acid (DPA; 22:5n-3) decreased with the storage time, irrespectively of the dietary treatment. Fillet lipid peroxidation increased with storage time but decreased with the dietary inclusion of HM. Overall, dietary replacement of fish meal by HM up to 19.5% (22.5% of total dietary protein) did not affect the fillet quality traits and shelf-life of European seabass while reducing fillet lipid oxidation.

Black Drum (Pogonias cromis) Shelf Life Comparing Three Packaging Technologies

ABSTRACT The shelf life of black drum was compared using three different packaging technologies: aerobic (AP), vacuum (VP), and modified atmosphere packaging (MAP). Tests included total volatile basic nitrogen (TVB-N), thiobarbituric-acid-reactive-substances (TBARS), pH, color, texture, aerobic plate count, Enterobacteriaceae, yeast, and mold over 20 days. MAP samples had lower microbial growth and less pH change than VP and AP samples. Color and texture of fillets did not vary significantly between sample groups. An increase in hardness was observed in all the treatments. This study demonstrated that MAP is most effective in extending the shelf life of black drum fillets.

EXPLORATORY STUDY OF NEAR AND SUPERCRITICAL CARBONDIOXIDE WARM PASTEURIZATION ON NILE TILAPIA

Effects of both near critical and supercritical CO2 pasteurization on inactivation of muscle protease and lipase of red tilapia (Oreochromis niloticus) were investigated along with its impact on microbial reduction and physical appearance. Near critical phase was designed at 70 bar and supercritical phases were designed at 80 and 90 bar. It was found that CO2 pressure had greater effect on protease inactivation than on lipase inactivation. Temperature increase did not improve both protease and lipase inactivation while fillet texture was adversely affected. The fillet color experienced color changes significantly.

Effects of different drying methods on quality changes and energy characteristics of tilapia fillets

The effects of different drying methods (hot air drying (HAD), microwave drying (MD), and hot air-microwave combined drying (HAMCD) processes) on the drying characteristics, rehydration ability, colour, texture, moisture state, microstructure, and energy characteristics of tilapia fillets have been investigated. The best rehydration and recovery ratios of tilapia fillets were obtained using HAMCD (58.96 and 39.24%, respectively). Tilapia fillets quickly become a burnt-yellow colour by MD. HAMCD can improve the hardness, chewiness, and elasticity values, and can obtain crispy tilapia fillets. In the moisture state peak image, the symmetry of the T21 (fixed water) peak obtained at 70 °C + 250 W (H3M) was the best with an asymmetry factor (As) of 1.04. In the MRI image, the brightness of the proton density weighted image was arranged from high to low as follows: HAD > HAMCD > MD. Using SEM, the microstructure of the tilapia fillets prepared using HAMCD showed a large number of small holes. The specific energy consumption was reduced ∼1.8 fold and the thermal efficiency increased ∼5 fold using HAMCD when compared with the HAD process. It was concluded that HAMCD can be used for to process tilapia fillets with high quality and low operating costs.

Genetic Improvement of North American Atlantic Salmon and the Eastern Oyster Crassostrea virginica at the U.S. Department of Agriculture–Agricultural Research Service National Cold Water Marine Aquaculture Center

AbstractUnited States marine aquaculture industries, which consist primarily of molluscan shellfish and Atlantic Salmon Salmo salar were valued at US$192 million in 2016. Coldwater marine aquaculture production has great potential for expansion, and both Atlantic Salmon and eastern oysters Crassostrea virginica are widely accepted as seafood by American consumers. Commercial salmon and oyster producers predominantly use stocks that are not many generations removed from wild, unselected stocks, so there is a need for continuous support to this industry through breeding programs. The National Cold Water Marine Aquaculture Center (NCWMAC) is the only long‐term program for developing genetically improved salmon and tools for the genetic improvement of eastern oysters in support of the U.S. coldwater marine aquaculture industry. The objectives of the program are to (1) expand and optimize approaches for multitrait selection in Atlantic Salmon and (2) advance genetic improvement technologies for the eastern oyster. Heritabilities for fillet color and fat, sea lice resistance, and growth of Atlantic Salmon were determined. The average gutted carcass weight for the genetically improved salmon was 5.91 kg/fish compared with 3.19 kg/fish for the control strain. The purpose of this article is to describe the current status of the NCWMAC research programs and summarize recent genetics gains.

Effect of partial replacement of polyphosphate with alkaline electrolyzed water (AEW) on the quality of catfish fillets

Effect of partial replacement of polyphosphate (50%) with alkaline electrolyzed water (AEW) on the water retention capacity, color, textural properties and lipid oxidation of catfish fillets was investigated. Catfish fillet samples were divided into five soaking group: Group 1 (AEW: pH = 11.6), Group 2 (EOA: AEW with 1.25 g/L sodium tri-polyphosphate, 0.3 g/L sodium metapolyphosphate, 0.4 g/L sodium polyphosphate, pH = 11.4), Group 3 (NEO: water with 2.5 g/L sodium tri-polyphosphate, 0.6 g/L sodium metapolyphosphate, 0.8 g/L sodium polyphosphate, pH = 9.0), Group 4 (WAT: tap water) and Group 5 (NOT: no soaking treatment). The results showed that AEW and EOA can improve catfish fillets weight gain and enhance water retention capacity similar to the phosphate enhancement treatment (NEO), but had no effect on product L* value and hardness and elasticity. For the total color difference (ΔE) and oxidation resistance, EOA treatment was better than AEW and NEO. Therefore, AEW alone or AEW with phosphate used in the traditional phosphate enhancement solutions can be used to enhance the quality of catfish fillets.

Effect of Black Mulberry (Morus nigra) Powder on Growth Performance, Biochemical Parameters, Blood Carotenoid Concentration, and Fillet Color of Rainbow Trout

Abstract The degree of flesh pigmentation is one of the most important quality criteria dictating the fish market value. It is well known that fish, like other animals, cannot synthesize their own coloring pigments de novo, and must obtain these pigments from their diet. In this study, four levels of black mulberry (Morus nigra) juice powder (BMP) as a natural pigment source were incorporated into a basal diet at concentrations of 0, 0.25, 0.5, and 0.75% and fed to rainbow trout weighing 100±5 g for 8 weeks in triplicate. At the end of the feeding trial, the effect of BMP on growth performance, blood biochemical parameters and fillet color was examined. Fish fed BMP showed significant enhancements in weight gain (WG), specific growth (SGR), food conversion ratio (FCR), and survival rates (SR) (P<0.05). SGR, WG and SR values were increased significantly following dietary supplementation with BMP in a dose dependent manner with the highest values in fish fed 0.75%, while the FCR was decreased (P<0.05). Body crude protein, lipid, and moisture contents were increased significantly in fish fed BMP (P<0.05). Dietary BMP has significantly decreased the levels of blood ALT, AST, and glucose (P>0.05). While the blood carotenoid concentration was increased in fish fed 0.5% BMP compared to other treated groups. Fish fed BMP showed increased fillet yellowness (b*) and redness (a*), while the fillet lightness (L*) was decreased when compared to the control (P<0.05). In conclusion, diets supplemented with BMP increased the growth performance, muscle pigmentation, and health status of rainbow trout.

INFLUENCE OF OPERATIONAL CONDITIONS OF SCALDING IN THE QUALITY OF BROILER CARCASSES IN INDUSTRIAL SCALE

The processing steps as scalding and de-feathering in the poultry industry have a great impact in meat quality. In this sense, the aim of this work is to evaluate the temperature effect (52, 57 and 62ºC), broiler weight (2.4-2.6, 2.8-3.0 and 3.2- 3.4 kg) and broiler processing line speed (4.000, 6.500 and 9000 broilers/h) of the scalding and de-feathering in the meat quality. An experimental design 23 was employed to evaluate the physical characteristics (absence of torn breast skin, epidermis, feather on wing and uropygium), color (L*, a*, b*), texture profile (hardness, adhesiveness, elasticity, cohesiveness, gumminess, chewiness, and resilience), and pH of broiler breast fillets. The pH did not suffer significant effect (p>0.05) of the variables between the ranges studied. In general, the better meat quality was obtained at 57°C scalding temperature, 3.0-3.2 kg weight and 6500 broilers/h processing line speed. In addition, these conditions are applicable to removal the epidermis, feather on wing and uropygium.

On-board Live Storage of Atlantic Cod (Gadus morhua): Effects of Capture Stress, Recovery, Delayed Processing, and Frozen Storage on Fillet Color Characteristics

ABSTRACT On-board live storage of Atlantic cod caught by trawl was evaluated as a potential method to improve the color characteristics of fillets. Before slaughter and processing, the fish were: (i) stored live for 3–6 h, (ii) kept in dry bin, or (iii) stored on deck for 5 h post capture (without bleeding). Blood chemistry and white muscle biochemistry were determined after capture and live storage. Fillet color and presence of discolorations were assessed on board (fresh) and after frozen storage (market quality). All fish were considerably stressed by capture and did not recover to baseline levels after live storage. Processing just after capture, live or dry bin storage, resulted in fillets with good color characteristics. Delayed processing (5 h) resulted in fillets with inferior color characteristics. The color characteristics of fillets evaluated on board and after frozen storage followed a similar pattern, although fillets from all treatments exhibited a more yellowish tint after frozen storage. Under the present catch and processing conditions, live storage on board did not improve the color characteristics of cod fillets. Color analysis indicated that consumers would only be able to identify worst-case fillets cut from unbled fish as being inferior to fillets from all other treatments.

Genetic and phenotypic evaluation of harvest traits from a comprehensive commercial Atlantic salmon, Salmo salar L., broodstock program

Twenty-two harvest carcass quantity and fillet quality traits, including nine calculated traits, were evaluated on 1496 North American origin farmed Atlantic salmon (mean weight ~5.5 kg) belonging to 81 families. Narrow-sense heritabilities along with a description of the variability of the traits, effects of sex and maturity status, and genetic and phenotypic correlations between the traits are presented and discussed. In addition, these traits are comprehensively compared to published results, when available, on Atlantic salmon and other fish species. All recorded carcass quantity traits were heritable (h2 = 0.30–0.48), indicating additive genetic control that can be exploited towards improvement, and their genetic and phenotypic correlations with one another are discussed. Quality traits related to melanin discoloration, gaping and marbling were less heritable (h2 = 0.04–0.15), but were at a reduced level overall in the group of salmon sampled. These secondary traits are considered useful as tracking traits to ensure their frequency does not increase over time due to genetic practices or to environmental factors that affect fish production. Fillet color was discussed from both visual and instrumental evaluation (h2 ≥ 0.42), including the negative and/or positive genetic and phenotypic correlations of varying degrees, making this trait difficult to incorporate into a selection index. Fillet color (all phenotypic measures) also lacked genetic and phenotypic correlations to fillet weight and other weight associated traits indicating that improvement in growth does not result in any changes in color. Calculated traits are presented related to yield, as these are often the most commonly discussed with commercial fish producers, resulting in moderate heritabilities (h2 = 0.14–0.27). Finally, implications of these harvest evaluation results to manage a commercial Atlantic salmon broodstock program are also discussed in detail.

Effects of an unprecedented summer heatwave on the growth performance, flesh colour and plasma biochemistry of marine cage-farmed Atlantic salmon (Salmo salar)

Global seawater temperatures are increasing and becoming more variable, with consequences for all marine animals including those in food production systems. In several countries around the world,arming of Atlantic salmon (Salmo salar) occurs towards the upper end of the thermal tolerance window for this species, and marked effects on salmon production during summers have been experienced but never empirically investigated. This project tracked the effects of an extreme summer heatwave on two different cohorts of fish stocked into farm cages either during early winter (EW) or late winter (LW). The farm site experienced an unprecedented high water temperature event, with a peak water temperature of 22.9 °C and 117 days above 18 °C. Fish in both EW and LW cohorts experienced a temperature-induced cessation of voluntary feed intake as well as inefficient osmoregulatory, liver and renal function during high temperature periods. Flesh colour declined primarily in the dorsal and ventral regions of the fillet and secondarily along the midline, with over 20% of fish demonstrated a complete loss of flesh colour during the months of March and April. A return to feeding in autumn occurred faster in some fish and caused a marked bimodal size distribution to appear within both the EW and LW cohorts as autumn progressed. However, the LW cohort returned to feeding at seawater temperatures of 20.2 °C, compared with 18.6 °C for the EW cohort. There was a strong positive relationship between fillet colour recovery and residual condition index (RCI). These findings identified alkaline phosphatase as a potential marker to non-destructively track individual fish for signs of recovery after a thermal stress event, and shed light on the physiological consequences of marine heatwaves on fishes. This study also identified that supporting feed intake or promoting a return to feeding may help mitigate the negative impacts of climate warming on cultured Atlantic salmon.

Effects of high pressure processing (HPP) on quality attributes of tilapia (Oreochromis niloticus) fillets during refrigerated storage

Fish fillets are extremely perishable in refrigerated conditions, so the use of technology is necessary to extend its shelf life. The present work aimed at evaluating high pressure processing effects on colour, texture, microbiological quality and sensory quality of tilapia fillets. Samples were pressurized at 100, 200, 300 or 400 MPa for 1 or 3 min. Colour parameters L* and whiteness of samples processed at 300 and 400 MPa were significantly higher (p < 0.05) than control samples. Both hardness and compression force of pressurized samples did not significantly differ (p > 0.05) from control. Counts of psychrotrophic microorganisms were significantly reduced (p < 0.05) on samples pressurized at 300 and 400 MPa. Samples processed at 200 MPa were preferred (p < 0.05) by assessors on sensory evaluation of fillets appearance. Colour, texture and microbiological analysis of samples kept at refrigerated storage (5 °C) for 1 wk showed that HPP at 400 MPa for 3 min was efficient to preserve tilapia fillets. The study has shown that HPP might be a suitable process for fish conservation, but influence on tilapia fillets appearance acceptance due to changes in colour may difficult its commercialization, so further research about these effects is needed.

Non-destructive assessment of final color and pH attributes of broiler breast fillets using visible and near-infrared hyperspectral imaging: A preliminary study

In poultry industry, the consensus is the final quality of chicken meat should be assessed at 24 h postmortem (PM). Visible and near-infrared (Vis/NIR, 400–1000 nm) hyperspectral imaging (HSI) was adopted to non-destructively assess final color (color24) and pH (pH24) of broiler breast fillets (pectoralis major). 25 fillets of the collected 75 broiler carcasses were deboned at each of three PM times (2, 4 or 24 h). To obtain representative spectra, regions of interest (ROIs) were extracted from hyperspectral images based on pixels selected from the 2-D scatter pixel plots of the first two principal component (PC) score images. Linear discriminant analysis (LDA) showed that color24 was affected by deboning time. Predictive models built with partial least squares regressions (PLSR) performed well for either a∗24 or b∗24 (Rp ≥ 0.87; RPD ≥ 2.02; RER ≥ 7.91), moderately for L∗24 (Rp = 0.75; RPD = 1.45; RER = 5.74), but unsatisfactorily for pH24 which was mainly due to its narrow value range (0.52). Simplified models based on optimal wavelengths selected by regression coefficients (RC) presented better predictive performances for a∗24 and b∗24 while slightly worse results for L∗24 and pH24. Distribution maps were created by pixels prediction in images, and color24 and pH24 within each broiler breast fillet were readily discernible. Overall, Vis/NIR HSI has a good potential to assess color24 and pH24 of chicken meat, but additional sample sizes should be further included to further enhance the prediction capability.

The effects of Lactococcus lactis subsp. lactis and its supernatant on some bacteriological and sensory values in Rainbow trout (Onchorhynchus mykiss) fillets

Lactic Acid Bacteria (LAB) have a great potential as bio-preservatives. The live cells and supernatant Lactococcus lactis subsp. lactis induced bacteriological changes in Onchorhynchus mykiss fillet by spray and immersion methods was studied during vacuum- packaged storage at 4 °C for 15 days. 40 kg of O. mykiss were prepared from a culture farm in Oshnavieh (Northwest Iran) and 112 fillet samples (100g) were prepared by aseptic method. L. lactis subsp. lactis (PTCC1336) bacteria was cultured in MRS culture medium. Its supernatant (2%, 4%) was extracted and 106 CFUml-1 dilutions of LAB were prepared and tested on the fillets to enhance their shelf life. All samples were evaluated regarding to growth of psychrotrophic, psychrophilic, mesophilic bacteria, molds and yeasts. Four characteristics including of odor, flavor, texture and color of fillets after and before cooking were evaluated for sensory analysis on days 1, 5, 10 and 15 and compared with control samples. The 4% supernatant and live bacteria were more effective than that of 2% and control (P&lt;0.05). The amounts of corrosive bacteria in 4% and live cells in storage time were less than human consumption limits (7log CFUg-1), whereas in control and 2% supernatant treatments were more than that limits. The results showed that increasing the percentage of supernatant was more effective on bacteriologic factors and enhanced sensory characteristics of rainbow trout fillets (P&lt;0.05).

Pumpkin seed cake as a fishmeal substitute in fish nutrition: effects on growth performance, morphological traits and fillet colour of two freshwater salmonids and two catfish species

ABSTRACTThe objectives of this study were to investigate the digestibility of pumpkin seed cake (PSC) for the rainbow trout, Oncorhynchus mykiss (Walbaum, 1792), and effects on performance and product quality traits of four different fish species when PSC partially replaced fishmeal in extruded diets. A digestibility trial was carried out to determine apparent digestibility coefficients (ADC) for crude protein (CP), ether extract (EE) and gross energy (GE) of PSC fed to rainbow trout. In subsequent growth trials, effects on performance and morphological traits and fillet colour values of four different fish species [rainbow trout; brook trout, Salvelinus fontinalis (Mitchill, 1814); African sharptooth catfish, Clarias gariepinus (Burchell, 1822); and wels catfish, Silurus glanis (Linnaeus, 1758)] were evaluated when 60% of fishmeal protein of a reference diet was replaced by PSC protein (based on digestible CP). Nutrient ADC of PSC were high (CP: 89%, EE: 88% and GE: 84%). No significant effects on growth and only minor effects on fillet colour were detected in the trials. However, replacing fishmeal with PSC at the chosen level affected morphological traits and feed conversion in all four species to different extents. Replacement effects of PSC should be tested at lower levels of inclusion before conclusions are drawn on its suitability in fish diets.

Descriptive sensory and instrumental texture profile analysis of woody breast in marinated chicken

The broiler industry is currently experiencing a muscle anomaly referred to as "woody breast," and the effect of different cooking methods on the marination properties of severe woody breast (SWB) has not yet been reported. This study compared the texture attributes of marinated (injected) normal (NOR) and SWB using a convection oven and a flat-top grill. The objectives were 1) to develop and validate a descriptive texture attribute panel with 6 trained panelists using a 16-point scale and 2) to evaluate the instrumental texture profile analysis (TPA) using a texture analyzer. Sixty-four NOR and SWB were obtained from a commercial facility. Fillet color (L*, a*, b*) and pH were measured before marination. In each of 2 trials, the breast muscles were injected in bulk with 15% brine (0.48 STPP, 0.55% NaCl, final concentration), and marinade retention was determined after 20minutes. The meat was vacuum packaged, stored at -20°C (7 d sensory; 29 d TPA) and then thawed (4°C, 24h). Fillets were cooked to 73°C on a flat-top grill (176°C) or in an oven (176°C), and cook loss % was determined. Panelist samples (2×2cm) and TPA samples (4×2cm) were cut into 3 pieces. Color and pH were higher for SWB than NOR fillets (P < 0.05). Marinade retention was 83.21% for NOR meat and 59.23% for SWB meat. The flat-top grill method resulted in higher cook loss than oven (P < 0.05). SWB had higher cook loss when compared to NOR (P < 0.05). Sensory texture descriptors springiness, hardness, denseness, cohesiveness, fracturability, fibrousness, crunchiness, and chewiness were higher for SWB than NOR fillets (P < 0.05). TPA attributes also showed higher values for SWB compared to NOR (P < 0.05). No differences in texture were found between the grill and oven for sensory and TPA attributes. In summary, marinated SWB has significant texture differences when compared to NOR, regardless of cooking method.