Effect of sustained exercise on white muscle structure and flesh quality in farmed cod (Gadus morhuaL.)

Abstract

Growth performance and white muscle cellularity were investigated in Atlantic cod (Gadus morhua L.) (500–600 g) to determine if texture and thereby quality is affected by exercise. Three exercise regimes [low flow, 0.5 body lengths per second (BL s−1) and 1.0 BLs−1] were applied, and the experiment was run for 9 months, at which point the fish had reached around 2 kg body weight. There were no significant differences in fork length or condition factors between groups that could be attributed to the exercise treatment, but the 0.5 BL s−1 group had significantly lower body weight performance than the control group. The average specific growth rate ranged from 0.37% to 0.42% per day. Muscle fibre diameter was positively correlated with fish weight. However, there was no difference in the distribution of muscle fibre diameters between treatment groups. A texture analyser, model TA‐XT2, equipped with a Warner–Bratzler shear blade was used to measure the texture of the fillet. No correlation was found between the shear force required to cut through the sample and the muscle fibre diameter, but the shear force decreased with increasing growth rate. A tristimulus colorimeter was used to measure the colour composition of the fillet instrumentally. Red/green chromaticity (a*) was positively correlated with the shear force. It was concluded that the exercise regimes tested were insufficient to influence either growth performance or muscle growth patterns. Individual variations in fibre diameter did not influence the colour or texture of the fillet.

Atividade proteolítica e crescimento de matrinxã em natação sustentada e alimentado com dois níveis de proteína

“…O aumento do IHS também foi observado em truta Oncorhynchus tshawytscha (Walbaum, 1792), mantida à velocidade de 1,5 CC s -1 (Kiessling et al, 1994b), e em bacalhau do Atlântico Gadus morhua (L., 1758), exercitado à velocidade de 1,0 CC s -1 (Bjørnevik et al, 2003). O IHS de matrinxã mantido em natação sustentada aumentou 6,5%, independentemente do nível proteico da dieta.…”

Texture Measurements in Fish and Fish Products

“…Johnston et al [45] found that firmness (taste panel) increased the fibre density in Atlantic salmon. On the contrary, neither Sigurgisladottir et al [28] nor Bjornevik et al [46] found a relationship between muscle fibre diameter and texture as measured by shear force. Now, there is increasing evidence that exercise prior to slaughter contributes to softening and gaping of fish flesh [12].…”

“…These studies provide an important basis for applied seafood research on fish flesh. It has been observed that the increase of muscle fibre size leads to a decrease in firmness and to an increase in the coarseness of the flesh [34,[44][45][46], and in turn such firm fibre size depends on where the fish grows, if in the wild or in a farm [34]. Firmness also depends on whether the fish is caught in the winter or in the summer [38].…”

“…Now, there is increasing evidence that exercise prior to slaughter contributes to softening and gaping of fish flesh [12]. Comparing the results from different studies on texture quality is complicated because of the use of different instrumental analysis on raw fish or sensory analysis on cooked fish, due to the inconsistent correlation between these two methods [4,46].…”

Optimization of sustaining swimming speed of matrinxã Brycon amazonicus: performance and adaptive aspects

“…(Piracicaba, Braz. ), v.67, n.3, p.253-258, May/June 2010 Hackbarth and Moraes, 2006), improvement of meat quality (Bugeon et al, 2003;Bjornevik et al, 2003), changes on poly-unsaturated fatty acids profile (Kiessling et al, 2005), and reduction of size heterogeneity (Christiansen and Jobling, 1990;Davison, 1997).…”