Rancidity development during the chilled storage of farmed Coho salmon (Oncorhynchus kisutch)

7 páginas, 4 figuras, 2 tablasCoho salmon (Oncorhynchus kisutch) is a fatty fish species whose farming production has greatly increased in recent years. Lipid damage produced during Coho salmon chilled storage was studied for up to 24 d. Lipid hydrolysis (free fatty acids, FFA) and oxidation (conjugated dienes; peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescent compounds formation, FR; browning development) were determined and compared to lipid composition (polyene index, PI; astaxanthin, AX) changes and sensory assessment (rancid odour development) results. Most lipid damage indices developed slowly during storage; thus, values obtained for FFA, PV, TBA-i and FR were in all cases under 1.5 g/100 g, 4.0 meq oxygen/kg lipid, 0.40 mg malondialdehyde/kg muscle and 0.40, respectively. Odour assessment showed a significant (p <0.05) rancidity development at day 10, when compared to starting fish material; then, non-acceptable values were obtained at days 19 and 24. The PI analysis showed not many differences during the storage time, with the lowest mean value at day 19. AX analysis indicated a relatively high content in the white muscle, which was maintained till the end of the experiment. A low oxidation development is concluded for Coho salmon lipids when compared to other fatty fish species under the same chilling conditions. AX was found to contribute to the oxidation stability of Coho salmon lipids, due to its free radical scavenger propertiesPeer reviewe

Chemical composition and quality loss during technological treatment in coho salmon (Oncorhynchus kisutch)

Coho salmon (Oncorhynchus kisutch) supports an important farming production in parallel with capture delivery, giving rise to products of great economic importance in many countries. This review covers the research carried out during the last decades related to its employment as a food product. In a first part, studies carried out concerning the chemical constituent composition and nutritional value are reviewed; a special attention is accorded to the wild/ farmed fish comparison and to the effect of diet on lipid composition variations. In agreement to the great lability of chemical constituents of aquatic foods, the second part of the manuscript provides a revision of coho salmon research related to the chemical component changes produced during technological processing and their effects on nutritional and sensory losses; in this case, a special attention is accorded to studies employing advanced technological strategies focused to partially inhibit the development of the different damage pathways.support provided by the Universidad de Chile (Chile)- Consejo Superior de Investigaciones Científicas (CSIC, Spain) research program through the following projects: Project 2003 CL 0013, Project 2004 CL 0038 and Project 2006 CL 0034. 43Peer reviewe

Influence of frozen and canned storage on the parameters of color, texture and thermal stability of golden kinglip (Genypterus blacodes) Influencia del congelado y enlatado sobre las propiedades del color, textura y estabilidad térmica de congrio dorado (

Changes in color, texture and thermal stability were determined for the golden kinglip species (Genypterus blacodes) frozen and stored at -18 °C and -30 °C for 6 months. In golden kinglip canned fish, these parameters were measured after 3 months of storage in two different filling media. In frozen and canned fish, color parameters did not increase significantly in L, a, b values (p &gt; 0.05). Compression strength measurements gave for the frozen fish values of 82.5 N to 124.9 N. Furthermore it was observed a decrease on the elasticity module through the time, being determined an initial value of 29.1 N/cm 2 and a final of 22.1 N/cm2. In canned samples a great increase on the golden kinglip was observed being measured, values between 59.5 to 675 N/cm2. The compression strength increased from 29.9 to 53.4 N/cm2 to N/cm2. In the determination of "dripping" (exudates by pressure) the greater change on "dripping" was observed during the first month of frozen, being subsequently appreciated

Development of lipid changes related to quality loss during the frozen storage of farmed coho salmon (oncorhynchus kisutch)

8 páginas, 4 figuras, 4 tablasLipid changes related to quality loss were evaluated during frozen storage of coho salmon for up to 15 months. Biochemical indices concerning lipid hydrolysis (free fatty acids, FFA) and oxidation (peroxide value, PV; thiobarbituric acid index, TBA-i; fluorescent compounds, FR; polyene index, PI) were determined and compared to sensory (odor and taste) and endogenous antioxidant (tocopherol isomers and astaxanthin) assessments. As a result of the frozen storage, lipid hydrolysis was shown to develop according to the increase in FFA content (p < 0.05). However, most biochemical lipid oxidation indices (PV, TBA-i and FR) led to a low degree of rancidity development (p < 0.05) when compared to other fatty fish species under similar frozen storage conditions. The PI value decreased (p < 0.05) at month 10 but then remained unchanged until the end of the experiment. Rancid odor and taste development were shown to be low throughout the experiment, according to the biochemical indices mentioned above. However, a progressive decrease (p < 0.05) in the original fresh odor and taste of salmon fish flesh occurred with increasing frozen storage time, such that fish samples had the poorest scores by month 15. Endogenous antioxidants were remarkably stable throughout the experiment and which might contribute to the oxidative stability of frozen farmed coho salmon lipidsThe research was carried out according to the Chilean-Spanish Cooperation Program ‘‘Universidad de Chile-Consejo Superior de Investigaciones Científicas (CSIC)’’, Projects 2003 CL 0013 and 2004 CL 0038). Mr. Marcos Trigo and Mrs. Laura Dı´az are gratefully acknowledged for technical assistance.Peer reviewe

Estudio de las modificaciones en proteínas de reineta (Brama australis), sometidas a congelación y almacenamiento a -18°C y -30°C

The objective of the present work was to study functional and thermal properties of reineta (Brama australis) frozen meat, analysed by water retention capacity (WRC), gel forming capacity (GFC), texture, emulsifying capacity and differential scanning calorimetry (DSC). For this study, reineta fillets were obtained and extracted by the same conditions, and cutted, packaged, frozen and stored at -18 degrees C and 30 C for 7 months. The results obtained, showed that there were no significant differences in the responses to thermal treatment for all the specimens. For samples frozen at -18 degrees C and -30 degrees C, the protein contents were 23.5 +/- 0.0 and 25.4 +/- 1.0%, respectively. The WRC values were 0.45 +/- 0.1 and 1.59 +/- 0.0 g water/g protein, respectively. The gel forming capacity was only present in the fresh samples, whereas the frozen stored ones only form protein aggregates. The emulsifying capacity was between 960 and 1400 g oil/g protein, and the storage time increased this value. The miosin denaturation temperature (T-d) and denaturation enthalpy (?H), obtained by DSC, fluctuated between 39.2 +/- 0.5 to 44.8 +/- 0.8 degrees C and 1.12 +/- 0.3 to 0.52 +/- 0.2 J/g, respectively. The actina values were between 71.0 +/- 0.6 to 75.3 +/- 0.5 degrees C and between 0.5 +/- 0.1 to 0.7 +/- 0.1 J/g. Cooperativity decreased as the storage time increased. This is showing a certain degree of protein displacement. The values found by thermal analyses showed a direct relationship with the functional properties, both decreasing with storage time

Estudio de las modificaciones en proteínas de reineta (Brama australis), sometidas a congelación y almacenamiento a -18ºC y -30ºC

El presente trabajo tuvo como objetivo estudiar las propiedades funcionales y térmicas en carne de reineta (Brama australis) congelada, mediante los análisis de capacidad de retención de agua (CRA), capacidad formadora de gel (CFG), textura, capacidad emulsionante (CE) y calorimetría diferencial de barrido (DSC). Para este estudio se utilizaron filetes de reineta obtenidos y extraídos bajo las mismas condiciones, los cuales fueron trozados, envasados, congelados y almacenados a temperaturas de -18ºC y -30ºC durante 7 meses. Los resultados para todos los tratamientos térmicos empleados no mostraron diferencias significativas entre individuos. Para los pescados congelados a -18ºC y -30ºC, los valores de proteínas totales fluctuaron entre 23,5 ± 0,0 y 25,4 ± 1,0 % respectivamente. Para el caso de CRA los valores se encontraron en un rango de 0,45 ± 0,1 y 1,59 ± 0,0 g agua/ g proteínas. En cuanto a la CFG sólo hubo formación de gel para la reineta fresca, existiendo producción de agregados proteicos para las muestras almacenadas. Por otra parte los valores de CE fluctuaron entre 960 a 1400 g de aceite/g proteína, con una tendencia al aumento a medida que el tiempo de almacenamiento fue mayor. Para el caso del DSC los valores de temperatura de desnaturalización (Td) y entalpía de desnaturalización (?H) de miosina fluctuaron entre 39,2 ± 0,5 y 44,8 ± 0,8 ºC y entre 1,12 ± 0,3 y 0,52 ± 0,2 J/g. Para la actina los valores fluctuaron entre 71,0 0,6 y 75,3 ± 0,5 ºC y entre 0,5 ± 0,1 y 0,7 ± 0,1 J/g, la cooperatividad disminuyó a medida que pasó el tiempo, lo cual está mostrando un cierto grado de desplazamiento de las proteínas. Los valores encontrados para propiedades térmicas presentan una directa relación con respecto a los valores de propiedades funcionales estudiadas, presentando ambos una disminución en el tiempo

Autolytic degradation and microbiological activity in farmed Coho salmon (Oncorhynchus kisutch) during chilled storage

7 páginas, 3 figuras, 3 tablasTwo deteriorative pathways (autolysis and microbiological activity) were studied in farmed Coho salmon (Oncorhynchus kisutch) for 24 days during chilled storage. These changes were assessed by nucleotide degradation (determination of adenosine 50-triphosphate and its degradation compounds) and biochemical (pH; content of total volatile base-nitrogen; trimethylamine-nitrogen, TMA-N; histamine) and microbial (total aerobe mesophiles, TAM; coliforms) indices related to bacterial activity. An important nucleotide degradation could be assessed according to the fast inosine 50-monophosphate formation, followed by degradation into inosine and hypoxanthine; the K value was found to be an accurate tool for the measurement of quality loss throughout the whole experiment. Regarding bacterial activity, contents of TMA-N and histamine and TAM counts assessment showed sharp increases after the end of the microbial lag phase (12– 17 days); however, values obtained for histamine content and TAM growth remained below acceptable security limits throughout the whole experiment.Chilean University-CSIC, Project 2003 CL 0013Peer reviewe

Influencia del congelado y enlatado sobre las propiedades del color, textura y estabilidad térmica de congrio dorado (Genypterus blacodes)

Se evaluaron los cambios en el color, textura y estabilidad térmica en congrio dorado (Genypterus blacodes) almacenado por 6 meses a –18 y –30 °C y en conserva. La blancura y la luminosidad del pescado congelado y en conserva aumentaron, pero no se produjeron cambios significativos en los valores L, a, b (p > 0,05) en el congelado. La medida de esfuerzo para el congelado entregó valores de 82,5 N a 124,9 N, en el módulo de elasticidad se observó una pérdida de elasticidad a través del tiempo, con un valor inicial de 29,1 N/cm2 y uno final de 22,1 N/cm2. En las conservas se ve un drástico aumento en la elasticidad del congrio dorado con valores que van entre 59,5 N/cm2 y 675 N/cm2 y el esfuerzo de cizalla aumentó de 29,9 N/cm2 a 53,4 N/cm2. En la determinación de “dripping” (exudado por presión) se produce el mayor cambio al primer mes de congelado, posteriormente se mantiene constante. En lo referente a la evolución en las proteínas vistas por el DSC, existe un deterioro debido al congelado por 6 meses de almacenamiento, siendo mayor el deterioro a –18 ºC que a –30 ºC, demostrado por los valores de entalpía, que son menores que al estado fresco