Effect of storage temperature on the bacterial flora and sensory quality of vacuum packaged smoked catfish (<i>Clarias anguillaris</i>)

Abstract

This study evaluated the effect of two storage temperatures on the bacterial flora and sensory quality of vacuum packaged smoked catfish (Clarias anguillaris). The catfish was hot smoked using a traditional kiln, with mangrove wood as the source of heat. Total bacterial count (TBC) and sensory parameters (colour, smell. dryness and general appearance) were determined during storage at ambient (28 ± 2°C) and refrigeration (4°C) temperatures for 0-8 weeks. Bacteria were enumerated, isolated and identified using standard methods. Vacuum packaged smoked catfish stored at 4°C (VPCR) had the lowest TBC which increased from 3.23 – 3.58 log₁₀ cfu/g within 2 weeks of storage and stabilized at 3.44 log₁₀ cfu/g for 4 – 8 weeks. The TBC of the vacuum packaged smoked catfish stored at ambient temperature (28 ± 2°C) ranged from 3.32 – 6.88 log₁₀ cfu/g within 6 weeks of storage. The bacteria isolated from fresh catfish belonged to nine genera, namely, Bacillus, Chryseobacterium, Escherichia, Lysinibacillus, Proteus, Pseudomonas, Staphylococcus, Streptococcus and Vibrio. Only Bacillus and Proteus species were isolated from freshly smoked catfish. Isolates from vacuum packaged samples were Bacillus, Lactobacillus, Proteus and Staphylococcus. Molecular characterization of three isolates from fresh catfish revealed that the species were Chryseobacterium aquifridigense, Lysinibacillus mycoides and Vibrio parahaemolyticus. The sensory scores for sample VPCR stored for 8 weeks did not differ significantly (P ≥ 0.05) from freshly smoked catfish, except for the colour. Non-packaged and vacuum packaged smoked catfish samples were of good quality during storage at ambient temperature for 4 weeks, and 4 – 6 weeks, respectively.