Microbial Quality, Safety, and Sensory Acceptability of X-ray Treated Fresh Channel Catfish Fillets

Abstract

This study was designed to determine if treatment with low dose X‐ray irradiation changes microbial quality (microbial load), safety (Listeria monocytogenes incidence), and sensory characteristics (aroma, appearance, and texture) of fresh aquacultured Channel catfish (Ictalurus punctatus) fillets during refrigerated storage. Fillets were treated to 0, 0.5, 1.0, and 1.5 kGy using an X‐ray irradiator and stored at 3°C for 17 days. Fillet aerobic plate count (APC), psychrotrophic plate count (PPC), total coliform count (TCC), and L. monocytogenes incidence were measured every 4 days during storage. A Difference-From-Control test was used to measure aroma, appearance, and texture. Fillet microbial counts were significantly different (p < 0.05) with time, irradiation dose, and the interaction of these two treatments. As expected, APC, PPC, and TCC increased as storage time increased. Overall L. monocytogenes incidence was 40%, 27%, 0%, and 7% at 0, 0.5, 1.0, and 1.5 kGy, respectively. Aroma of irradiated and non‐irradiated catfish fillets was significantly different, with greater aroma differences recorded as storage time increased due to progressional spoilage of the untreated controls. However, there were no significant aroma differences noted among the different irradiation doses. Neither appearance nor texture was significantly different between any treatments throughout testing. This study indicated that exposure to low dose X-ray irradiation improved the microbial quality and safety of fresh catfish fillets without affecting sensory acceptability at time of purchase.