Application of capillary electrophoresis for the identification of Atlantic salmon and rainbow trout under raw and heat treatment.

Accurate authentication of related species is necessary to prevent the illegal replacement of species of higher quality and/or price with lower-quality, less expensive species. Atlantic salmon (Salmo salar), an expensive and valuable species, can be intentionally substituted with rainbow trout (Oncorhynchus mykiss). Using the technique of capillary zone electrophoresis (CZE), the identification of raw species was based on the analysis of muscle sarcoplasmic (water-soluble) proteins, while for canned species identification was based on muscle proteins solubilized with urea and sodium dodecyl sulfate (SDS). Either water or urea-SDS extracted proteins gave reproducible and distinct electrophoretic patterns of proteins for both species independent of storage conditions. Although data analysis indicated changes in protein profiles for both species during storage, species identification was still possible. In addition, quality determination during refrigerated and frozen storage involved the use of two freshness indexes: K value (the relationship between inosine monophosphate, inosine, and hypoxantine) and pH. A linear correlation was found between changes in electrophoretic patterns and K values for refrigerated salmon species. Trout kept in storage for six days reached a constant K value higher than the maximum limit for a product of good quality, preventing determination of any correlation with electrophoretic pattern. The protein profiles obtained by CZE during long storage revealed their potential for monitoring both differences between fish species and changes in quality during refrigerated, frozen, and canned storage of the species under study.

Estudio de las modificaciones en proteínas de reineta (Bramas australis): sometidas a congelación y almacenamiento a 18°C y 30°C / Stydy of the reineta protein modifications (Brama australis): put under freezing and storage to 18°C and 30°C

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 emulsionanate (CE) y calorometría diferencial de barrido (DSC). Para este estudio se utilizaron filetes de reinetas obtenidos y extraídos bajo las mismas condiciones, los cuales fueron trozados, envasados, congelados y almacenados a temperaturas de 18°C y 30°C durante siete meses. Los resultados para todos los tratamientos térmicos empleados no mostraron diferencias estadísticamente significativas entre individuos. Para los pescados congelados a 18°C y 30°C, los valores de proteínas totales fructuaron entre 23,5 ± 0,0 y 25,4 ± 1,0 por ciento 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 de protéicos 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 y desnaturalización (T) y entalpía de desnaturalización (?H) de miosina fluctuaron entre 39,2 ± 0,5 y 44,8 ± 0,8°C 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°C 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 demostrando 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

[Study of the reineta protein modifications (Brama australis), put under freezing and storage to -18 degrees C and -30 degrees C]. / 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 degrees C for 7 months. The results obtained, showed that there were no signifficant 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 (Td) 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.

[Effect of thermal treatments on the chemical characteristics of mora crab meat (Homalaspis plana)]. / Efecto de tratamientos térmicos sobre las características químicas de carne de jaiba mora (Homalaspis plana).

Marine species muscles present non-proteins nitrogenated compounds, used as quality index. They are total volatile basis (NBVT), trimethylamine oxide (TMAO) and trimethylamine (TMA). pH is considered too as a quality index. The aim of this work was to evaluate these parameters in a fresh and canned marine product from the V region, corresponding to mora crab (Homalaspis plana). Fresh pincer meat from mora crab was extracted and kept in ice until theits analysis and thermal process of the canned product. A 3(2) statistical design was applied, considering two variables with 3 levels: 15, 30 y 45 minutes time levels: 80 degrees, 100 degrees y 121 degrees C temperature levels. Nine conditions of time-temperature were obtained. The thermal treatment caused an increase in pH and BVT. The TMA was increased since reduction of TMAO.

Efecto de tratamientos térmicos sobre el contenido de lisina disponible en carne de jaiba mora (Homalaspis plana) / Effect of thermal treatment on the available lysine content of mora crab (Homalaspis plana) meat

The effect of different high temperatures treatments on the available lysine content of mora crab meat, was studied. Fresh pincer meat from mora crab (from the V region) was extracted and kept in ice until the thermal process of the canned product. A 3(2) statistical design was applied, considering the following variables temperature (80 degrees C, 100 degrees C and 121 degrees C) and time (15, 30 and 45 minutes). Nine conditions temperature-time were obtained. Nutritional properties from available lysine were studied. A decrease from 8.33 (in raw meat) to 6.01 g/g protein in the most drastic thermal conditions, was observed. It ca be concluded that the content of available lysine in mora crab meat is more affected by time than by the temperature of the thermal treatments. Therefore the nutritive quality can be maintained applying high temperature and short time treatments.