This Is AuburnElectronic Theses and Dissertations

Texture Analyses of Catfish: A Genetics Approach




Johnson, Andrew

Type of Degree

Master's Thesis


School of Fisheries, Aquaculture, and Aquatic Sciences


Channel catfish (Ictalurus punctatus) and hybrid catfish (channel catfish ♀ × blue catfish (Icatlurus furcatus) ♂) aquaculture dominates the US aquaculture industry. These catfish genetic types have been heavily researched to improve aquaculture production traits, improve yield and the overall performance. Significant research has been devoted to the culture of catfish but not towards improving meat quality, an important consumer attribute. Multiple studies were conducted using channel catfish, blue catfish, and the hybrid catfish to evaluate their carcass, texture, sensory, and color traits of catfish fillets. The first study conducted evaluated texture, sensory, and color traits of channel catfish, blue catfish, and hybrid catfish at three size classes: below market sized (<0.68 kilograms), market sized (0.68-0.92 kilograms) and above market sized (>0.92 kilograms). Results of this study revealed that with increasing size, hardness, chewiness, gumminess, and toughness attributes increased in channel catfish and hybrid catfish (p<0.001). This phenomenon was not observed in blue catfish. When market sized hybrid catfish and channel catfish are compared, the channel catfish had higher means for all texture traits, was observed to be more tough and fibrous than the hybrid catfish fillets (p<0.05). Hybrid catfish were observed to have a mushier fillet (p <0.05) The second study evaluated fish quality parameters of commercial catfish fillets to imported Vietnamese swai fillets (Pangasianodon hypophthalmus) due to the impact imported swai fillets have on the domestic aquaculture market. This study revealed that control swai fillets were tougher, harder, and chewier than domestically farmed catfish (p<0.05). With a treatment of sodium phosphate, these differences between US catfish and Vietnamese swai were nullified, and the resulting fillet was more mushy and less fibrous than controls of both fillet products. Comparison of texture, sensory, and color traits of catfish fillets from 7 channel catfish strains revealed several strain and sex effects (P<0.05). Strain differences were observed for fillet %, redness of the fillet, hardness, cohesion, and all sensory traits evaluated except flavor. Further analysis in a third study examined combining ability of channel catfish dams and blue catfish sires in their hybrid progeny and revealed that additive genetic variance was found in channel catfish dams for hardness, chewiness, and gumminess. Specific combining ability estimates revealed dominance and epistasis interactions for fillet yield, resilience, springiness, and yellowness of the fillets. Lastly, a heritability study of channel catfish in a 50 x 50 cross-fostering design revealed additive genetic variance for fillet yield and redness of the fillet. Direct selection for sensory and texture traits was not feasible, however, heritability estimates revealed the potential to implement a genetic enhancement protocol for increasing fillet % and decreasing redness of channel catfish fillets. Increasing fillet % from the same sized channel catfish and decreasing redness in fillets would prove to be beneficial for the catfish industry and increase profits to channel catfish farmers and processors due to the detrimental effects red fillets have in the catfish market. Redness had a low but potentially significant genetic correlation with yellowness of the fillet, and selection against redness would also potentially decrease yellowness in channel catfish fillets.