Rainbow Trout Meat Research Articles

MICROBIOLOGICAL QUALITY ASSESSMENT OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) MEAT TREATED WITH ROSEMARY AND THYME DRIED HERBS AND ESSENTIAL OILS

This study investigates the effects of thyme and rosemary dried herbs, as well as thyme and rosemary essential oils (1%, w/v), on the microbiological quality of vacuum-packed rainbow trout meat stored under refrigerated conditions (4 ± 1 °C) for 7 days. The microbiological quality of meat was monitored based on total viable counts, coliform bacteria, and lactic acid bacteria counts over a designated storage period (on the 0th, 1st, 3rd, 5th and 7th day of storage). As expected, the highest total viable counts were observed on the 7th day of storage in the untreated aerobically packed control group reaching 5.723 ± 0.021 CFU.g-1. The tested treatments showed potential in reducing the growth of bacteria in rainbow trout meat samples. Across all bacterial groups under investigation, rosemary essential oil appears to have the most advantageous effect in inhibiting bacterial growth compared to other tested treatments. Cultivated isolates were identified by MALDI-TOF mass spectrometry and assigned to 33 species belonging to 14 families. The most prevalent family was Enterobacteriaceae (18.99%), and the most abundant species found in samples was Hafnia alvei (8.86%). Our findings suggest the potential of using thyme and rosemary in both essential oil and dried forms as natural preservatives to enhance the microbiological quality and longevity of refrigerated rainbow trout meat.

Method for obtaining ecological products from rainbow trout Oncorhynchus mykiss farming

In aquaculture, the period of active development of aquatic organisms is considered one of the most important for the formation of potential in the future. The issue of using natural components when growing aquatic organisms and feeding young fish is given special attention. This research investigated Spirulina (25%) + Vermiculture (50%) + Hermetia illucens (25%) as an additional source of functional active substances and protein that affect the body performance of rainbow trout in early ontogenesis. All objects were cultured in a special bioreactor, which was a component of the recirculating aquaculture model system as well as in the laboratory, where an installation was made for cultivating natural food. The results of the scientific and practical part of the work showed that after the end of the experiment, body weight was higher in the experimental fish by 7.2% than in the control group. This article presents the results of feeding rainbow trout as one of the cases of improving the morpho-functional and biochemical composition of the blood of this species: an increase in the total number of red blood cells by 11.0%, hemoglobin content by 9.7%, total protein at 22.7%, albumin by 24.2%, and creatinine by 15.5%, compared with the control group. The presented positive changes in the functional status of the rainbow trout organism were in harmony with the parameters of body weight, as well as histological indicators. Histological indicators of the liver and muscle tissue of the fish supplemented the obtained positive result of the influence of natural and active components of the feed. Feeding fish according to the scheme in the experimental group promotes the formation of layers of special adipose tissue in the endomysium. The total amount of the stromal component in the muscle tissue of rainbow trout was 25% of the mass of the entire tissue. The control group showed that the muscle fibers were polygonal in cross section, separated from each other within the bundle by delicate layers of endomysium. When using a standard feeding regimen (control group), the stromal component is a moderately expanding structure that replaces the space between the fibers. The experimental group had the most significant indicators. The intensification of individual aspects of homeostasis achieved with the help of feed components (experimental group) promotes the growth of muscle fibers in thickness due to the formation of new fibrils, but not an increase in the proportion of sarcoplasm (watery meat). As a result, neurohumoral regulation and substance synthesis processes improved in the fishes’ body, which helps to improve ontogenesis rates. The presented ingredients in the diet of rainbow trout are natural stimulants of metabolic processes and sources of nutrients. The method allows aquaculture to be defined as being as close as possible to “environmentally safe”. The next stage will be a comprehensive analysis of the qualitative and quantitative characteristics of rainbow trout meat under the influence of the feed factor.

Effectiveness evaluation of the infl uence of protein concentrates on the chemical composition of fish meat

Due to the high demand, cost, growing shortage and low quality of fi sh-meal, there is a constant search for affordable alternative feed raw materials in feeding aquaculture fi shing grounds. The use of high-protein products of plant origin is the most effective option for replacing fi sh-meal in fi sh feed. The purpose of the work was to evaluate the eff ectiveness of the infl uence of protein concentrates on the chemical composition of rainbow trout meat. Testing of compound feed for rainbow trout, the formulation of which included high-protein feed concentrates, was carried out on the basis of IP Kalmykova I. O. and under the conditions of the Research Center “Breeding valuable sturgeon breeds” at the Volgograd State Agrarian University. It was found on base of the results obtained that more intensive growth was observed in the groups in which the mustard protein-containing feed concentrate Gorlinka was introduced into the feed formulation with partial or complete replacement of sunfl ower meal. Here, the increase in the total and average daily live weight gain was noted by 2,83–6,93 % and by 1,62–1,68 %. The use of the Agro-Matic concentrate during the period of the experiment had a positive eff ect on the growth dynamics of rainbow trout, increasing productivity indicators. Thus, live weight indicators increased by 1,29–4,15 %, daily gain indicators increased by 1,44–4,46 % relative to individuals receiving compound feed with fi sh-meal. When studying the chemical composition of trout meat with the addition of Gorlinka concentrate to the feed formulation in the experimental groups, the increase in protein content was revealed by 0,13–0,41 abs.%, inorganic matter by 0,04–0,12 abs.%, also the total amount of amino acids increased by 0,18–0,46 abs.%, while the fat content on the contrary decreased by 0,05–0,17 abs.% compared to the control. In the experimental trout groups, when introducing the Agro-Matic protein concentrate into the diet instead of fi shmeal the protein content increased by 0,03–0,40 abs.%, inorganic matter by 0,08–0,24 abs.%, total amino acids increased by 0,11–0,58 abs.%, there was a slight decrease in the amount of fat by 0,10–0,36 abs.% compared to the 1st control group. The use of protein concentrates has a positive eff ect on the qualitative composition of the muscle tissue of rainbow trout by increasing the protein content and the amount of essential amino acids in the muscle tissue of individuals surpassing the 1st control group in key indicators.

Comparison of Nutritional Composition, Mineral and Heavy Metal Content of Rainbow Trout from Different Aquaculture Systems

In this study, proximate compositions, meat yields, mineral matter (Na, Mg, Ca, K), and heavy metal (As, Fe, Zn, Se, Mn, Co, Cu, Pb, Ni) contents of rainbow trout (Oncorhynchus mykiss) obtained from concrete pond systems and dam lake net cage were examined. Mineral and heavy metal contents were measured by ICP-OES instrumental analyser. According to the results of rainbow trout meat yield and nutritional composition analysis varied between; meat yield were 57.43-66.40%, crude protein were 16.99-19.93%, crude fat were 3.07-4.18%, crude ash were 0.98-1.58%, and moisture contents were 75.10-77.65%. Mineral contents of Ca 2.66-30.58 mg.kg-1, Na 19.53-36.04 mg.kg-1, K 252.79-310.05 mg.kg-1, and Mg 120.75-137.44 mg.kg-1 were detected in the presented ranges. Detected heavy metals were As 0.42-0.56 mg.kg-1, Fe 2.16-3.69 mg.kg-1, Zn 2.67-4.69 mg.kg-1, and Se 0.17-0.77 mg.kg-1. On the other hand, Mn, Co, Cu, Pb, and Ni were not detected. As a result of the study, it was found that the proximate composition, meat yield, mineral matter, and heavy metal contents of rainbow trout vary depending on the location and size of the fish (p<0.05). However, the heavy metal levels detected in muscle tissue did not exceed the consumption limits.

Proximate and fatty acid composition of meat from rainbow trout (Oncorhynchus mykiss W.) after dietary supplementation with black pepper (Piper nigrum L.) extract

The study was aimed at assessing the effect of dietary supplementation with black pepper (Piper nigrum) on the chemical and fatty acid composition in the meat of rainbow trout (Oncorhynchus mykiss W.), farmed in a recirculating system.
 Rainbow trout were distributed in two groups – experimental fed 1% powdered extract from black pepper (BPE) and control (C) fed without black pepper extract. After the end of the experiment, 6 fish from each group were euthanized, filleted and deboned. The 1% BPE in rainbow trout feed reduced meat water content and increased dry matter percentage and fat content. The fatty acid profile of rainbow trout meat was beneficially influenced by the dietary BPE supplement. The SFA percentage was statistically significantly decreased whereas contents of UFA, MUFA, PUFA and n-3 were considerably higher. No consistent effect was noted with respect to n-6 fatty acids. The improved PUFA/SFA and n-6/n-3 ratios in the supplemented group showed that the tested feed additive had a favourable effect on fatty acid content of rainbow trout meat. Both ratios were within the range, beneficial for human nutrition: > 0.4 and < 5, respectively.

Influence of Essential Oils on the Microbiological Quality of Fish Meat during Storage.

Simple SummaryFish meat is highly perishable due to its composition and the naturally present microbiota. The food industry aims to provide healthy, safe, and high-quality products to the market. Several strategies, including the use of natural preservatives, may be used to enhance food shelf life, and they can also be combined with others, such as vacuum packaging. This being the case, essential oils are natural plant components that, due to their composition, possess high antimicrobial and antioxidant effects, and are therefore good candidates to be tested as fish preservatives together with vacuum packaging. In the present study, essential oils from Citrus lemon and Cinnamomum camphora were added to rainbow trout meat for evaluating the microbiological quality (counts of bacteria and identification of present microbiota) of the fish when vacuum packed and stored for 7 days at 4 °C. Our results show that lemon (0.5% and 1%) as well as C. camphora essential oils (0.5% and 1%) had a positive effect on the microbiological quality of fish meat, keeping a high microbial quality of the fish fillets during 7 days of cold storage. The use of these essential oils in combination with vacuum packaging is beneficial in extending the shelf life of rainbow trout meat. All isolated species under the tested conditions are identified in the present study; such information will be useful for the future development of preservation methodologies that target isolated microorganisms, which will enable the food industry to enhance the shelf life and safety of fish.The aim of the present study was to evaluate the microbiological quality of rainbow trout meat treated with essential oils (EOs from Citrus limon and Cinnamomum camphora) at concentrations of 0.5% and 1.0% in combination with vacuum packaging during storage. The composition of the EOs were analyzed by gas chromatography coupled with mass spectrometry, and total viable counts (TVCs), coliform bacteria (CB), and lactic acid bacteria (LAB) were determined on the zeroth, first, third, fifth, and seventh days of storage at 4 °C. Individual species of isolated microorganisms were identified using a MALDI-TOF MS Biotyper. The results show that the major components of the EOs were linalool (98.1%) in C. camphora and α-limonene in C. limon. The highest number of TVCs and CB were 4.49 log CFU/g and 2.65 log CFU/g in aerobically packed samples at the seventh day. The lowest TVCs were those of samples treated with 1% C. camphora EO. For CB the most effective treatment was 1% lemon EO. LAB were only detected in a few samples, and were never present in aerobically packed samples; the highest number of LAB was 1.39 log CFU/g in samples treated with 1% lemon EO at day seven. The most commonly isolated coliform bacteria were Hafnia alvei, Serratia fonticola, Serratia proteamaculans, Pantoea agglomerans, and Yersinia ruckeri. Lactobacillus sakei, Staphylococcus hominis, and Carnobacterium maltaromaticum were the most frequently isolated bacteria from lactic acid bacteria. In conclusion, C. camphora EO at a concentration of 1% showed the highest antimicrobial activity.

Biological efficiency of rainbow trout meat lipids depending on the levels of amino acids in fodder

In trout farms of Ukraine, when using compound fodder for their production, the question arises of clarifying the requirement of rainbow trout in energy, protein and amino acids to achieve the maximum realisation of its biological productivity potential. Accordingly, the research explored the effect of using complete fodder with various levels of lysine and methionine on the biological efficiency of rainbow trout meat lipids. The purpose of the experiment was to determine the effect of different levels of amino acid nutrition of commercial rainbow trout on the fatty acid composition of meat lipids and their biological efficiency. For this purpose, five experimental groups were established by the method of analogues. The experiment lasted 210 days and was divided into two periods: equalising (10 days) and main (200 days). During the equalisation period, the feeding diet was the same for the fish of the control and experimental groups. During the main period, the level of lysine and methionine in the experimental fodders for different experimental groups of trout ranged from 2.5 to 2.9% and from 0.8 to 1.0%, respectively. Feeding of rainbow trout during the study period was performed 4-6 times a day, during the daytime at regular intervals. The required amount of fodder was calculated according to the individual weight of the fish and the temperature of the environment during feeding. Cultivation of marketable two-year-olds was performed in ponds with an area of 100 m2 at a planting density of 50 specimens/m2 and a water level of 1 m. The total number of trout in the experimental studies was 25 thousand specimens. It is established that the main share of fatty acids of lipids of rainbow trout meat is saturated fatty acids and monounsaturated fatty acids. As a result of the research, it was determined that using feed with increased levels of lysine and methionine for fish of the 4th experimental group was accompanied by an increase in the content of the sum of saturated fatty acids in meat by 5.84% compared to the control. With the growth of amino acid nutrition of the fodder, there is an increase in the content of linoleic acid in trout m′eat by 0.19-0.24% compared to the control. The practical value of the scientific work is to substantiate approaches to the technological bases of increasing the efficiency of using fodder nutrients in trout farming to ensure high fish productivity, which is of great economic importance

Investigation of dependences of the morphological composition of body and amino acid composition of trout meat proteins (Oncorhynchus mykiss) on levels of the energy value of feeds

The article studies the effect of using complete compound feeds with different energy levels on the morphological composition of the body and the amino acid composition of trout meat proteins. The experiment aimed to establish the influence of different levels of energy nutrition of commercial rainbow trout on the morphological composition of their body and the amino acid composition of meat proteins. For this purpose, five experimental groups were formed using the analog method. The study lasted 210 days and was divided into two periods: comparative (10 days) and main (200 days). During the comparative period, the study fish consumed compound feed of the control group. During the main period, the energy level in experimental compound feeds for different experimental trout groups ranged from 16 to 20 mJ per 1 kg. It was found that with an increase in the mass of two-year-old trout, the mass of muscle tissue and the yield of edible parts probably increases. Feeding fish with an increased amount of metabolic energy (20 mJ.kg-1) resulted in a significant change in the weight of internal organs, including the heart, liver, and kidneys. Increasing the metabolic energy in the compound feeds of fish from 18 mJ.kg-1 to 19 – 20 mJ.kg-1 leads to a significant increase in bowel mass by 13.3 – 5.0%. An increase in the level of metabolic energy in rainbow trout diets from 18 mJ.kg-1 to 19 – 20 mJ.kg-1 contributed to a likely increase in the methionine content in meat. A similar pattern was observed for the tryptophan content. It was found that the content of most essential amino acids in the protein of rainbow trout meat exceeds the corresponding values in the "ideal" protein, except for the content of isoleucine and leucine, which refers them to limiting amino acids.

Eryngium caeruleum essential oil as a promising natural additive: in vitro antioxidant properties and its effect on lipid oxidation of minced rainbow trout meat during storage at refrigeration temperature

Background: One of the most common species of oily fish is rainbow trout. Chemical deterioration of oily fish species is principally caused by lipid oxidation. The adverse effects of various chemical preservatives caused consumer’s attention to shift to natural alternatives. Eryngium caeruleum is an herbaceous plant that is native to the northern areas of Iran and is used in various local foods. The aim of the present study was to investigate the effects of different concentrations of E. caeruleum essential oil (EEO) on the physicochemical and oxidative stability of minced rainbow trout meat for 20 days storage at 4±1°C.Methods: Firstly, the chemical compounds and total phenolic content of EEO were determined by gas chromatography-mass spectrometry and Folin–Ciocalteu reagent, respectively. Then, in vitro antioxidant capacity of EEO was evaluated using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) methods. Finally, the minced rainbow trout meat was mixed with different concentrations of EEO, and physicochemical and oxidative stability of treatments were investigated for 20 days storage at 4±1°C.Results: According to the results, 0.4% EEO significantly improved the chemical stability of minced fish compared to the control group at the end of storage period with the following scores (P<0.05): pH value (6.3), peroxide value (11.88 meq/kg of lipid) and thiobarbituric acid reactive substance (0.43 mg MDA/kg sample).Conclusions: In order to increase the chemical quality characteristics of minced fish, new ingredient systems that are associated with natural and organic foods are applied. The results of present study indicate that the use of EEO in the meat industry can develop the novel healthy fish products and improve its chemical stability.Keywords: Eryngium caeruleum, Oncorhynchus mykiss, Natural antioxidant, Chemical stability, Lipid oxidation

Efficacy of stinging nettle extract in combination with ε-polylysine on the quality, safety, and shelf life of rainbow trout fillets.

The effects of incorporation of stinging nettle extract (3% and 6%) and ɛ‐polylysine (0.1% and 0.2%) on chemical, microbial properties, and stability of rainbow trout fish fillets wrapped in polyethylene bags (in atmosphere condition) and refrigerated for 12 days at 4°C were evaluated. No remarkable differences regarding the chemical composition of rainbow trout fish (protein, moisture, fat, and ash content) resulting from the treatments were noted. The lowest TBARS (thiobarbituric acid reactive substance) and the highest phenolic compounds were noted in samples treated with 6% SNE + 0.2% ɛ‐PL on day 12, while the highest inhibitory effects against the growth of TVC, psychrotrophic bacteria, coliform, yeast, and molds corresponded to samples treated with 6% SNE (T4 and T5) at day 12. During the storage, the samples' TVB‐N (total volatile base nitrogen) increased, whereas the total phenolic content of the rainbow trout samples declined. The rainbow trout samples treated with 6% SNE + 0.2% ɛ‐PL had the highest amount of redness and the lowest TVB‐N values. Therefore, these natural ingredients could be used to maintain rainbow trout meat quality and shelf life.

Eryngium caeruleum essential oil as a promising natural additive: in vitro antioxidant properties and its effect on lipid oxidation of minced rainbow trout meat during storage at refrigeration temperature

Background: One of the most common species of oily fish is rainbow trout. Chemical deterioration of oily fish species is principally caused by lipid oxidation. The adverse effects of various chemical preservatives caused consumer’s attention to shift to natural alternatives. Eryngium caeruleum is an herbaceous plant that is native to the northern areas of Iran and is used in various local foods. The aim of the present study was to investigate the effects of different concentrations of E. caeruleum essential oil (EEO) on the physicochemical and oxidative stability of minced rainbow trout meat for 20 days storage at 4±1°C. Methods: Firstly, the chemical compounds and total phenolic content of EEO were determined by gas chromatography-mass spectrometry and Folin–Ciocalteu reagent, respectively. Then, in vitro antioxidant capacity of EEO was evaluated using 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2' azino-bis (3- ethylbenzthiazoline-6-sulphonic acid) (ABTS) methods. Finally, the minced rainbow trout meat was mixed with different concentrations of EEO, and physicochemical and oxidative stability of treatments were investigated for 20 days storage at 4±1°C. Results: According to the results, 0.4% EEO significantly improved the chemical stability of minced fish compared to control group at the end of storage period with the following scores (P<0.05): pH value (6.3), peroxide value (11.88 meq/kg of lipid) and thiobarbituric acid reactive substance (0.43 mg MDA/kg sample). Conclusions: In order to increase the chemical quality characteristics of minced fish, new ingredient systems that are associated with natural and organic foods are applied. The results of present study indicate that the use of EEO in the meat industry can develop the novel healthy fish products and improve its chemical stability.

Impact of Carboxymethyl Cellulose Coating Incorporated with Rosemary Essential Oil and ‎sodium Acetate on the Quality and Shelf Life of Rainbow Trout Fillet‎

ABSTRACT The objective of the current research was to evaluate the impact of sodium acetate (SA) and rosemary essential oil (REO) on the microbiological and physicochemical characteristics of rainbow trout coated with carboxymethyl cellulose (CMC) and kept for 16 days at 4°C. The CMC coating was supplemented with isolated SA or SA combined with REO (0.5% or 1%). The gas chromatography-mass spectrometry (GC-MS) evaluation indicated that the REO was chiefly composed of 1,8-cineole (25.21%) and α-pinene (22.34%). The microbiological evaluation revealed that the growth of mesophilic bacteria, psychrotrophic bacteria, Pseudomonas spp., lactic acid bacteria, and Enterobacteriaceae was considerably slower in rainbow trout meat coated with CMC, SA, and REO (0.5 or 1%) relative to the control. Such coatings also improved the pH, water-holding capacity, cooking yield index, and sensory characteristics of rainbow trout fillets. The total volatile basic nitrogen content, peroxide value, and amount of thiobarbituric acid reactive substances were significantly lower in the experimental samples relative to the control. Hence, we introduced a novel CMC coating containing SA and REO (0.5 or 1%) that improves the shelf life and quality of refrigerated rainbow trout meat.

Effects of Sodium Alginate and Chitosan Coating Combined with Three Different Essential Oils on Microbial and Chemical Attributes of Rainbow Trout Fillets

ABSTRACT Meat products, such as fish meat, are known to be susceptible to undesirable chemical and microbial reactions that characterize spoilage. In this study, the effect of a sodium alginate and chitosan coating incorporated with Mentha piperita, Artemisia dracunculus, and Zataria multiflora essential oils on chemical and microbial attributes of rainbow trout meat was evaluated during storage at 4°C. Chemical and microbial assays were performed on rainbow trout fillets with alginate and chitosan coatings and 0.2% concentration of test essential oils. The results showed that the alginate coating with essential oils significantly decreased production of thiobarbituric acid (TBA) and total volatile basic nitrogen (TVBN) and reduced the growth of foodborne spoilage bacteria during storage at 4ºC. At day 12, the best results were obtained in chitosan coating + Z. multiflora, with 5.96 ± 0.12, 4.93 ± 0.12, and 3.83 ± 0.2 for total viable counts, psychrotrophic bacterial count, and lactic acid bacteria count, respectively. Moreover, the lowest amounts of chemical analysis were observed in chitosan coating + Z. multiflora at the final day (0.54 ± 0.03 and 20.31 ± 0.1 for TBA and TVBN, respectively). Our study revealed that essential oils can be used as effective natural components against undesirable chemical and microbial reactions in fish meat.

Meat Quality of Rainbow Trout (Oncorhynchus mykiss) and Brown Trout (Salmo trutta fario) Farmed in Bulgaria

Background: Fish meat is outlined with high nutritional value having essential amino acids, unsaturated fatty acids, mineral and vitamins. In this short report, we compared the meat quality of rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta fario) farmed in Bulgaria. Methods: Ten fishes from each species were purchased from a fish farm and their morphological parameters were determined. The technological properties of meat were analyzed such as water holding capacity and cooking loss as well as chemical composition such as water content, protein, fat, dry matter, and ash. Results were processed by STATISTICA 6.0 software. Results: Higher values were significantly determined in brown trout for standard body length (p&lt;0.05), body height (p&lt;0.001), and body width (p&lt;0.01); while differences in total body length were not relevant (p&gt;0.05). Water holding capacity of rainbow trout meat (9.49±3.86%) was considerably better (p&lt;0.001) than that of brown trout meat (15.85±1.11%). Cooking loss in rainbow trout (31.78±6.17%) was lower (p&lt;0.001) than that of brown trout meat (44.48±4.20%). Protein, fat, and dry matter contents were higher in brown trout (p&lt;0.001). No statistically significant differences were found out with respect to ash content (p&gt;0.05). Conclusion: Meat of rainbow trout cultivated in Bulgarian farm exhibited better technological properties than that of cultivated brown trout; however, nutritional value of brown trout meat was superior.

Effects of native and modified starches on the physicochemical and textural properties of rainbow trout (Oncorhynchus mykiss) fish burgers

ABSTRACTNative and modified starches of chayotextle and potato were mixed with rainbow trout meat, and the resistant starch content, pH, water-holding capacity (WHC), malonaldehyde content, sensorial properties and texture profile of the rainbow trout fish burger (RTB) were investigated during 21 days of storage at 0°C. The addition of acid-modified starches (AMS) to RTB resulted in a high content of resistant starch (RS). The RTB with added native and modified starches showed a better stability of pH, WHC and texture profile values during the 21 days of storage. The lipid oxidation values of the RTB control showed higher values than the RTB with added native and modified starches. In the sensory evaluation test, the RTB supplemented with AMS have the highest score regarding acceptability. The result confirmed the potential of modified starches as a prebiotic food ingredient, since they improve the physicochemical and sensorial properties of RTB.

Meat Quality of Rainbow Trout (Oncorhynchus Mykiss) from the Bistrișorii Valley Trout Farm, Alba County

Fish meat represents a great energy source in human nutrition, due to its content in high biological value protein, lipids which contain omega acids and minerals. The chemical composition of fish meat can be influenced by several factors such as: species, administered feed, environment, age and spawning period. The aim of this research was to analyse the chemical composition of the rainbow trout meat reared in the fishery Valea Bistrişorii, in a classical system. The determination of water (W %), minerals (M %) and dry matter (DM %) content was performed by calcination. The crude fat (CF %) was determined by Soxhlet method and crude protein (CP %) by the Kjeldahl method. Analysing the chemical composition of the rainbow trout meat, the following values were obtained: W = 73.60 ± 0.23%; DM = 26.40 ± 0.14%; CP = 18.21 ± 0.14%; CF = 6.87%; M = 1.32%.The obtained data offers useful information of meat chemical composition for selection of future breeders and improving the rainbow troutraised in the Bistrişorii Valley.

Pre-harvest Modulation of N-3 Long-chain Polyunsaturated Fatty Acids in Rainbow Trout Meat for Human Consumption

Since post-harvest improvement of food quality depends on the pre-harvest stage, controlling food quality at the pre-harvest stage is being recognized as an important aspect of food processing technology. n-3 Long-chain polyunsaturated fatty acids (n-3 LCPUFAs) are considered important factors in the suppression of cardiovascular disease and development of the infant brain and visual functions. Fish meat generally contains a larger amount of n-3 LCPUFAs than meat from terrestrial animals, but the amount of n-3 LCPUFAs in fish meat depends on their dietary fatty acid intake. In order to supply n-3 LCPUFAs to consumers, we developed a finishing-up method, through a 4-day lysine-deficient diet feeding for rainbow trout (Oncorhynchus mykiss) meat. This 4-day lysine deficiency did not affect fish body weight, while significantly increased the total lipid content in the muscle tissue. In addition, docosahexaenoic acid and total n-3 fatty acid contents increased significantly in the meat throughout the 4-day finishing treatment. We concluded that the finishing-up method using short-term lysine-deficient diet feeding enables us to enrich fish meat with n-3 fatty acids for human consumption.

A study on incubation of Brown Trout (Salmo trutta sp.) eggs and feeding of fry

In this study, spawning, incubation success or survival rate of brown trout and initial feeding of fry were investigated. The wild broodstock in this study were caught in Akcay river in Sapanca. In July 2008, 7 female and 1 male fish with a body weight between 300-350 g were brought to the Istanbul University, Faculty of Fisheries Sapanca Inland Waters Research Center (Adapazari, Turkey). These fish were kept in fiberglass adaptation tanks and were fed fresh rainbow trout meat. During this period, fish were fed with 9 mm pelleted feed. In June 2009, when fish had reached an average weight of 2500-3000 g, the first biometric measurements on the fish were performed. In early March 2010, about 3000 eggs were stripped from one female broodstock and sperms from the male brown trout. After the fertilization, the eggs were placed in horizontal incubators. The eye development started on the 21st day and hatching began on the 30th day. Hatching was found to be approximately 74%. When fish run out of their yolk sac, fry were divided into three groups of 600 individuals per tank and kept under same incubation conditions. Fry were fed feeds such as Artemia sp., fresh lamb liver, microdiets (300, 500 and 700µm) and extruded pellet feed (1mm). For the first group, fry were started on Artemia for seven weeks and continued on microdiets and extruded pelleted feed. For the second group, fry were started on microdiets and continued on extruded pellet feed. For the third group, fry were started on fresh lamp liver for a month and continued as the other groups. Fry were fed multiple times a day to satiation. Water used in the experimental tanks was from the research center. Average parameters recorded included water temperature of 11.5oC, pH of 7.86 and DO of 9.6 mg/L. At the end of the experimental period, the number of dead fry were 77, 104 and 123 in the first, second and third groups respectively. In conclusion, the present study indicated that the first generation eggs incubation from wild broodstock brown trout adapted to culture conditions successfully. However, further studies on the first feeding at the fry stage are encouraged. Keywords: Brown trout, broodstock culture, egg incubation, survival, fry nutrition

Study of the heavy metals (Cd and Pb) content in the tissues of rainbow trouts from Hamedan coldwater fish farms

The aim of this research was to determine the concentration of cadmium (Cd) and lead (Pb) in the muscle and liver tissues of rainbow trout (Oncorhynchus mykiss) in Hamedan Province (west of Iran) cold water fish farms, and compare the results with the FAO/WHO guidelines. Heavy metal concentrations were determined from the three randomly selected fish farms by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) method. Concentration of heavy metals were detected to be high in rainbow trout during dry season. Concentration of Cd and Pb in the muscle and liver tissues were 3.67µg/kg and 12.82µg/kg, respectively. However concentrations of these two heavy metals were within the standard limits set and recommended by FAO/WHO, indicating that the rainbow trout meat raised from this region is safe for human consumption.

The Quality of Rainbow Trout (Oncorhynchus Mykiss) Cultured in Various Polish Regions

Abstract There is a lack of regulations regarding labeling of the place of cultivation of freshwater fish, even though some research indicates that environmental factors can influence the quality of rainbow trout meat. The purpose of this study was to assess the necessity of such regulations and to determine the meat quality of rainbow trout cultivated in different regions of Poland. The analysis of color measurement, fatty acid profile, sensory evaluation and microbiological analysis of trout muscle were performed to assess the influence of cultivation region on the quality of trout meat. The place of cultivation did not influence the redness (a*) and yellowness (b*) of fillet, but had impact on lightness (L*). The microbiological analysis showed no pathogenic microorganisms on the fish surface. The fatty acids composition differed highly significantly (P&lt;0.01) depending on the place of cultivation. Since there are significant differences in quality and nutritional value between studied samples, the necessity of labeling the place of cultivation of rainbow trout for the final consumer should be implemented.