An assessment of red fillet prevalence in the catfish industry

Authors: ALLEN, PETER - Mississippi State University; ALLRED, SHAY - Mississippi State University; SHAO, W - Mississippi State University; SCHILLING, M - Mississippi State University; PETRIE-HANSON, LORA - Mississippi State University

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2019
Publication Date: 4/5/2019
Citation: Allen, P.J., Allred, S., Shao, W., Schilling, M.W., Petrie-Hanson, L. 2019. An assessment of red fillet prevalence in the catfish industry. Aquaculture. 507:203-210. https://doi.org/10.1016/j.aquaculture.2019.04.020.
DOI: https://doi.org/10.1016/j.aquaculture.2019.04.020

Interpretive Summary: In the commercial catfish industry, quality of fillets is extremely important to maintain customer satisfaction. When fillet problems commonly occur, they need to be investigated and understood in order to change management leading to their occurrence. Red fillet is a common fillet problem, but the magnitude and economic scope of the problem is not well understood. Therefore, researchers at Mississippi State University in collaboration with catfish processors evaluated the frequency of red fillet occurrence at processing plants and estimated the associated economic costs. In addition, researchers also evaluated whether bacteria were similar among red fillets, to determine if their were common causes leading to red fillet. The research team found that red fillet was common, occurred in a small percentage of fillets, but could account for substantial losses on an industry-wide basis. Similar bacteria were found associated with red fillets. Researchers recommended continuing investigations into culture practices and associated bacteria to determine if management actions could be used to reduce the problem.

Technical Abstract: Nonstandard Channel Ictalurus punctatus and Hybrid I. punctatus × I. furcatus Catfish fillets are rejected by catfish processors primarily due to aberrations in muscle texture or coloration (i.e., yellow, pink, red), and represent an economic loss for both the processer and farmer. Of these fillet types, red fillet is characterized by red coloration, with affected areas ranging from a solitary spot to the whole fillet. The present study investigates the prevalence of red fillet within the catfish industry and evaluates compositional differences in fillets by means of color, proximate composition, and microbial presence between red (diffuse red patch), punctured (singular red spot), and acceptable fillets. Red fillets with presence of different bacteria were also compared histologically. In order to evaluate the occurrence of red fillet, subsamples of acceptable and rejected fillets were obtained biweekly from a commercial processing plant over the course of a year, with rejected fillets sorted as red, punctured, or neither. Red fillets accounted for an average of 0.13% fillets from each pond harvest, representing an estimated annual loss of $443,000 for catfish farmers and $683,000 for catfish processors. Red and punctured fillets did not significantly differ in color (lightness and redness), pH, fat, protein, or moisture. Red and punctured fillets were darker, redder, and yellower than acceptable fillets. Acceptable fillets had more fat and less moisture than red and punctured fillets. Microbial analyses were similar for both red and punctured fillets with Aeromonas sobria being the most prevalent bacterium (62%) followed by Plesiomonas shigelloides (28%) and A. hydrophila (19%). Fewer acceptable fillets had bacteria than red or punctured fillets, with A. sobria as the most abundant bacterium (24%). The prevalence of A. sobria in red catfish fillets may warrant further investigation into the effect of bacteria on the development of red fillets in intensively-reared Channel and Hybrid Catfish.