Rainbow Trout Meat Research Articles

Effect of Feeding Frequency on Body Composition of Rainbow Trout ( Oncorhynchus mykiss -Walbaum, 1792) Fingerlings

A 21-days experimental trial was conducted to examine the influence of feeding frequency on body composition of rainbow trout fingerlings. A number of 295 trout fingerlings (with mean initial weight ±SD of 5.53±0.25g), from Cislau fish farm, Buzau city, were equally stocked in four rearing units. The two experimental variants ( feeding frequency 2 meals/day -F1 and 4 meals/day -F2) were each applied for two tanks. At the end of the experiment, fish meat biochemical composition was significantly influenced (p<0.05) by feeding fr equency. Keywords: rainbow trout, meat biochemical composition, aquaculture recirculating systems Introduction. Optimum feeding frequency, for maximum fish growth may vary according to fish species, size and culture conditi ons, including feed quality, amount of feed administrated and water temperature values throughout the experimental trial (Lee et al., 2000). One of the factors that lead to choose an ap propriate feeding frequency consists in determining the time between meals, because feed consumption is closely related to stomach capacity, gastric emptying rate and digestion (Bret t, 1971; Riche et al, 2004). A feeding frequency between 1-3 meals/day is reported to be p roper for rainbow trout. Aims and Objectives. Knowing the fact that biochemical composition of meat is influenced by several factors such as fish size, ag e, environmental and feeding conditions, the present study was conducted to determine the influe nce of feeding frequency on growth and body composition of rainbow trout fingerlings, in c onditions of using different feeding frequencies. Materials and Methods. The experiment was carried out between October 25 and November 16, 2010 at the pilot recirculating system of Aquaculture, Environmental Science and Cadastre Department from Dunarea de Jos University of Galati. The experimental system consisted of 4 four growing units with a tot al volume of 0.336 m 3 (0.35◊0.80◊0.120m) each and water quality maintenance module, represented by water mechanical and biological filtration units, water sterilization unit (represe nted by a UV lamp) and water oxygenation unit and 295 trout fingerlings. The two treatments (feed ing frequency of 2 meals/day -F1 and 4 meals/day -F2) were each applied for two tanks. On the first six days of experiment, fish were fed with a ratio of 3%/BW/day and then, the ratio i ncreased up to 5% on the eighth day; after that the ratio remained constant till the end of th e trial. The rainbow trout meat biochemical determinations were performed on muscle tissue samples and later, from the mixture, homogeneous samples were taken. Proteins were determined with Gerhardt type equipment by using Kjeldahl method, fats were determined by Soxhlet solvent extraction method (petroleum ether) with Raypa extraction equipment, dry matter was determined by heating at temperature of 105 ±2oC using Sterilizer Esac and a sh was evaluated by calcification at temperatures of 550±20°C in a Nabertherm furnace. Results and Discussions. The results regarding the biochemical composition of rainbow trout meat, fed under different feeding fre quencies conditions are presented in Fig. 1 . After statistical analysis were made, significant d ifferences (p<0.05) were registered for all

Residues of Oxytetracycline in Cultured Rainbow Trout

Nowadays, antibiotics are widely used in aquatic animals to control and treatment of infections or as food supplement for growth increase and animal output. With increasing use of veterinary drugs in food production, there is global consideration about the consumption of antimicrobial residues in aquatic foods and their effects on human health. This study was aimed to evaluate the Oxytetracycline (OTC) residues in Rainbow trout meat in Shahre-kord (Iran) markets before and after frying. After randomized collection of 50 samples of fish in Shahre-kord markets in a six months period were examined. The prepared samples were examined for OTC residues using HPLC analytical method before and after frying. Results showed that 3 (6%) of the samples before frying and 12 (24%) after frying were having lower than Maximum residual limits (MRLs) in Codex alimentarius. However, mean OTC residues before and after frying samples were above MRLs. The mean amounts of OTC were 2260 +/- 1090 and 1110 +/- 930 ng g(-1) before and after frying, respectively. These findings show that the frying of fish reduces OTC residual. Nevertheless, the usage of OTC should be reduced to an acceptable level in fishery industry.

Effects of marination, cooking and storage on physico-chemical and microbiological properties of ready to eat trout döner kebab

The aim of this work was to investigate the use of rainbow trout (Oncorhynchus mykiss) in ready to eat doner kebab production and determine the effects of marination, cooking and storage conditions (4 and −18 °C) on physico-chemical and microbiological properties of doner kebab. The raw trout meat, raw, cooked and stored doner kebab samples were subjected to moisture, protein, fat, ash, color, pH, cholesterol, biogenic amines, lipid oxidation, fatty acids profile, texture, microbiological and sensory analysis. The results indicated that the major fatty acids in trout doner kebab were palmitic, stearic, oleic, omega-3 and omega-6 fatty acids and unsaturated fatty acids were higher than saturated fatty acids (p < 0.05). Low biogenic amine and cholesterol contents were determined in doner kebab. It was found that −18 °C of storage temperature was more effective than 4 °C for inhibition of lipid oxidation and microbial growth in trout doner kebab (p < 0.05). While cooking affected parameters evaluated (p < 0.05), marination did not have any significant effect. The study results indicated that using rainbow trout meat in doner kebab production could be beneficial to provide healthy meat products without posing any acceptability problems in terms of quality factors. This is the first paper to be reported on physico-chemical and microbiological properties of doner kebab produced with rainbow trout and effects of marination, cooking and different storage temperatures on these physico-chemical and microbiological properties.

Concentration of Biogenic Amines in Rainbow Trout (Oncorhynchus mykiss)Preserved in Ice and its Relationship with Physicochemical Parameters of Quality

Biogenic amines are formed as a result of amino acid decarboxylation and are linked to food deterioration. Analysis of these metabolites may be of great importance to determine food quality. The aim of this study was to quantify the biogenic amines (putrescine and cadaverine), and evaluate the physicochemical parameters (pH, ammonia and total volatile bases) of rainbow trout meat (Oncorhynchus mykiss). Fifteen samples were packed in ice and transported in a Styrofoam container to the laboratory. Analyses were performed daily until the 15th day of storage. Biogenic amines concentrations and pH increased significantly throughout the storage period. No significant differences were observed in total volatile bases values over the time. Ammonia was detected after the 11th day of storage. Based on these results, cadaverine and putrescine may be used as a quality index of rainbow trout; however, total volatile bases may not be adequate parameter for this matrix.