The quality of frozen African sharptooth catfish (Clarias gariepinus) fillets under long-term storage conditions

Abstract

The quality of frozen catfish fillets was monitored over a period of 11 months at −20 °C, in two types of packaging materials, namely vacuum packaging (VP) and oxygen-permeable packaging (OPP). Representative samples (n = 5) from both types of packaging materials were drawn at random, monthly for the full period of the trial. Samples were pooled and analysed microbiologically using standard methods. Fatty acid analyses of total lipids, neutral lipid, glycolipid and phospholipid fractions as well as sensory evaluation were also conducted every 3 months on the pooled samples. These tests were conducted to determine whether OPP (cheaper option) could be used instead of VP for long-term superchilling of catfish without detracting from its quality. Low microbiological counts were maintained throughout the trial, ie 4.1 × 104 cfu g−1 (VP) and 8.9 × 104 cfu g−1 (OPP) in the 11th month for aerobic plate count. No significant human pathogens were isolated, with the exception of Aeromonas hydrophila (Stanier). Lipid oxidation, irrespective of packaging, showed no fixed trends during the 11 months of investigation. Also, no significant deviation from sensory characteristics was noted. These results indicate that storing catfish fillets in OPP is a feasible and cheaper option for long-term freezing. © 2001 Society of Chemical Industry