Trypanorhynch cestodes parasitizing Mugil liza (Mugiliformes: Mugilidae) commercialized in the state of Rio de Janeiro, Brazil / Cestoides Trypanorhyncha parasitando Mugil liza (Mugiliformes: Mugilidae) comercializados no estado do Rio de Janeiro, Brasil

Abstract The aim of the present study was to identify, through morphological and morphometric analyses, the species of trypanorhynch cestodes found as plerocerci in the intestinal serosa of Mugil liza and to determine their parasitic indices. One hundred and fifty specimens of this mullet collected off the coast of the state of Rio de Janeiro were necropsied and the trypanorhynch cestodes found were fixed and preserved as whole mounts for morphological analysis. The plerocerci were identified as Callitetrarhynchus gracilis and Pterobothrium crassicole, both with a prevalence of 0.67%, an intensity of 1 and abundance of 0.0067, in single infections. This is the first record of a trypanorhynch cestode parasitizing M. liza in Brazil. Although the parasitic indexes were low, from a hygienic-sanitary perspective the plerocerci of these species are visible to the naked eye, and thus can disgust consumers and make marketing the fish unfeasible.

Resumo O presente estudo objetivou determinar taxonomicamente as espécies de plerocercos de cestoides Trypanorhyncha encontradas na serosa intestinal das tainhas Mugil liza, através do estudo morfológico e morfométrico e indicar seus índices parasitários. Foram coletados 150 espécimes desta espécie de tainha do litoral do estado do Rio de Janeiro. Após as necropsias, os cestoides Trypanorhyncha encontrados foram fixados e preservados em montagens permanentes para permitir a análise de suas estruturas morfológicas. Os plerocercos foram identificados como Callitetrarhynchus gracilis e Pterobothrium crassicole e ambas as espécies apresentaram prevalência de 0,67%, intensidade de 1 e abundância de 0,0067, em infecções únicas. Este é o primeiro registro de cestoides Trypanorhyncha parasitando M. liza no Brasil. Quanto ao aspecto higiênico-sanitário, vale ressaltar que, embora os índices parasitários registrados tenham sido baixos, os plerocercos dessas espécies estavam visíveis a olho nu, podendo causar repugnância ao consumidor e inviabilizar a comercialização do pescado.

Evaluación física y química de filetes de lebranche (Mugil liza) en almacenamiento congelado a -18°C / Physical and chemical evaluation of lebranche fillets (Mugil liza) in frozen storage at -18°C

El objetivo del presente estudio fue evaluar los parámetros físicos y químicos de filetes de lebranche (Mugil liza) durante su almacenamiento en congelación a -18°C, por cinco meses. Inicialmente, los pescados fueron caracterizados mediante el análisis proximal (humedad, proteínas, grasa y cenizas), talla y peso. Las determinaciones para la evaluación de la estabilidad de los filetes congelados fueron realizadas mensualmente y se determinó: pH, ácido láctico, color (L, a y b), humedas, solubilidad de proteínas en soluciones salinas (SPs), capacidad de retención de agua (LE), degradación de nucleótidos adenosinamonofosfato (AMP), inosina (Ino), hipoxantina (Hx) y textura. La pérdida de la calidad de la proteína fue más evidente al segundo mes de almacenamiento, cuando los parámetros como SPs disminuyó a 45,12 por ciento y LE aumentó a 17,50 por ciento en comparación al principio del estudio con valores de SPs de 74,88 por ciento y LE de 3,52 por ciento, estos resultados muestran un daño significativo en las proteínas durante el tiempo de almacenamiento. En los filetes congelados, los cambios autolíticos fueron básicamente por el pH, ácido láctico e Ino, sin embargo, éstos fueron considerablemente lentos debido a la baja temperatura empleada en este estudio. Cambios de color fueron detectados en los músculos blanco y rojo de los filetes, mostrando diferente comportamiento durante el almacenamiento, en el primero el color rojo (parámetro "a") disminuyó, mientras en el músculo rojo aumentó, pero la luminosidad (parámetro "L") se incrementó en el músculo blanco y disminuyó en el rojo. En este trabajo, el tiempo de almacenamiento mostró diferencias significativas (P<0,05) con: pH, ácido láctico, color, humedas, SPs, LE, nucleótidos y textura. Los filetes mostraron un buen grado de frescura hasta el segundo mes, después del cual la calidad disminuyó.

The objective of the present study was to evaluate the physical and chemical parameters of lebranche (Mugil liza) fillets during frozen storage at -18°C for five months. Initially the raw fish were characterized for proximate analysis (moisture, protein, fat and ash), size and weight. Test for frozen fillets stability were performed monthly in order to determine: pH, lactic acid, colour (L, a and b), moisture, solubility of proteins in saline solutions (SPs), water-binding capacity (WBC), nucleotide degradation adenosine monophosphate (AMP), inosine (Ino), hypoxantine (Hx) and texture. Lost of the protein quality was more evident at the second month of storage, when parameters like SPs drop to 45.12% and WBC increased to 17.05% in comparison to the beginning of the study with values of SPs of 74.88% and WBC of 3.52%, these results showed significant protein damage during the storage time. In the frozen fillets autolytic changes were basically in pH, lactic acid, and Ino but these were considerably slowly for the low temperature employed in this study. Colour changes were detected in the white and red muscle fillets, and they showed different behavior during the storage time; in the first the red colour (parameter “a”) decreased, meanwhile in the red muscle redness was increased, but the luminosity (parameter “L”) were increased in the white muscle and decreased in the red muscle. In this research the storage time shows significant differences (P<0.05) with: pH, lactic acid, colour, moisture, SPs, WBC, nucleotides and texture. Fillets showed good grade of freshness until the second month, after that quality decreased.