The Effects of Natural Preservatives on the Sensory Properties and Shelf Life of Channel Catfish Ictalurus punctatus

摘要

This study explored the effect of three natural preservatives, lemon juice, vinegar and grapefruit seed extract (GFS), on reducing foodborne illnesses caused by food pathogens and spoilage bacteria on channel catfish ( Ictalurus punctatus). The minimum inhibitory concentrations (MIC) of these preservatives were determined using six specific spoilage bacteria species previously isolated from channel catfish. The zone of inhibition test confirmed the antimicrobial activity of these natural products. Microbial changes of catfish fillets were evaluated after marinating the catfish in the preservatives during storage at 4 °C. Bacteria enumeration was done every other day for 27 days. Consumer groups performed sensory evaluation on baked marinated catfish evaluate acceptability with respect to color (appearance), aroma, flavor, and texture on days 1 and day 5 (after storage at 4 °C and --20 °C). The application of GFS, lemon juice, and vinegar extended shelf life by 7 days, 9 days, or 27 days, respectively compared to the control. The acceptable bacteria threshold value was defined as106 Log CFU/g. The sensory analysis of the catfish samples resulted in no significant differences (p > 0.05) between the treatments and the control on day 1 and day 5 (4 °C). Storage at --20 °C resulted in a significant color difference (p = 0.018) in catfish samples. Synergy was found between lemon and vinegar at 2%*2% using the checkerboard method of fractional inhibitory concentration (FIC). Protein analysis on SDS-PAGE gel showed protein denaturation. In conclusion, natural preservatives extended the shelf life of channel catfish with vinegar extending the most by 27days and retained the sensory properties.