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The aim of this study was to evaluate the main quality parameters in relation to two different carp culture systems. The quality of common carp fillet, such fat content, fatty acid composition, textural properties and sensory parameters, was evaluated. Carps were harvested from semi-intensive (SIS) and extensive (ES) systems, respectively. The results show no significant differences between the groups in organoleptic tests. However, significant differences (P < 0.05) were observed in the textual parameters (especially hardness). A difference in the fat content and fatty acid profile (P < 0.05) between two different carp culture systems was also observed. This study shows that the quality of common carp fillets particularly depends on the culture system used. Feeding strategies as well as general pond management are therefore of critical importance to enhance the overall quality of common carp fillets and meet the consumer demands. PRACTICAL APPLICATIONSThe present study gives insight into the effects of different rearing systems and feeding strategies on important quality properties such as fat content and texture of carp fillets. We showed that feeding strategies as well as general pond management are of critical importance to enhance the quality of common carp fillets and meet the consumer demands. Fish farmers can use the obtained knowledge to produce carp according to the customers demand. As consumer preferences with respect to fat content and softness have shown a regional variability, the used culture system and the resulting quality should be indicated at the market.

The aim of the study was to evaluate the differences in texture profile of tench flesh. Texture profile analyses in tench, two years old, (Tinca tinca L.) was investigated using instrumental texture profile method, focused on hardness, springiness, cohesiveness, gumminess and chewiness performed with Texture Analyser TA.XTPlus. One group of fish was raised extensively in natural earth pond conditions; the other group was intensively cultured in a recirculation system, feeding on a commercial diet for 7 months. Twelve fish (6 females and 6 males) from each group were used for analyses. Flesh of male tench in both groups was harder, more gummy and chewy, compared to female. Springiness was lower in tench male from intensive culture and cohesiveness lower in females from both groups. The result of texture analysis in the extensive culture group was 16.01 N for hardness and 0.72, 0.66, 10.73 and 7.69 for springiness, cohesiveness, gumminess and chewiness, respectively. In the intensive culture group it was 15.16 N for hardness and 0.59, 0.52, 8.06 and 4.96 for springiness, cohesiveness, gumminess and chewiness, respectively. The results proved that the flesh of fish raised extensively is harder, springier, more cohesive and more gummy, and thus more appealing to consumers. This is the first similar study of texture profile of tench. Cohesiveness, hardness, muscle, springiness, flesh qualityTextural quality is primarily a sensory attribute that is quantified in foods by several instrumental methods. According to Bourne and Szczesniak (2003) and Cardoso et al. (2009), texture profile analysis (TPA) is a resulting force-generated time curve used to quantify a number of textural properties that correlate well with the results from sensory evaluation.Post mortem textural changes are caused directly or indirectly by physicochemical changes in myofibrillar proteins (Křížek et al. 2011) and changes in extracellular structure such as the loss of fibre compaction and the increase of extracellular space between fibres (Ingolfsdóttir 1997;Popelka et al. 2012). Muscle texture is also affected by other variables such as fish rearing, seasonality and methods of capture, handling and processing (Johnston et al. 2000;Periago et al. 2005). The main quality indicators for fresh fish are fat, colour, texture and freshness. Other indices commonly cited are white stripes (connective tissue), bloodstains, marbling and melanin. Double compression used in the instrumental procedure enables performing TPA as a plot of force-time curves (Rahman 2006). Other terms describing texture are firmness, stiffness and the yield point (Vácha et al. 2007). Many attempts have been made to correlate physical measurements with sensory evaluation of texture (Johansen et al. 1991;Chamberlain et al. 1993). Reproducibility of texture measurements is affected by the sampling technique due to heterogeneity of the fillets (Nesvadba et al. 2004). Therefore, it is difficult to find a representative average sample in fish and measurements of textural propert...