Quality assessment of smoke-dried Clarias gariepinus and Chrysichthys nigrodigitatus stored in two storage facilities

Abstract

The quality of smoke-dried fish can be enhanced by storing the products in good storage facilities. This research was carried out to determine the proximate composition, microbiological quality and sensory properties of smoke-dried Clarias gariepinus and Chrysichthysis nigrodigitatus stored in refrigerator and kitchen cabinet during a 6-week storage period. Sensory properties were assessed using panel of assessors. Bacterial load was done using plate count agar spread plate technique. Fish were purchased alive, washed, sacrificed and smoked for 72 hours. Percentage weight loss after smoking C. gariepinus and C. nigrodigitatus were 57.42% and 65.91%, respectively. Results for crude protein, moisture and lipid content of smoke-dried C. gariepinus stored in refrigerator ranged between 67.80-68.31%, 8.32-9.00% and 12.15-12.34% while the values for those stored in kitchen cabinet ranged from 67.04-68.30%, 8.30-8.49% and 12.15-12.34, respectively; for smoke-dried C. nigrodigitatus the ranges of the nutrients were 61.75-62.20%, 7.40%-8.00, 16.15-16.28% and 60.89-62.19%, 7.40-7.49%, 16.15-16.28% for those stored in refrigerator and kitchen cabinet, respectively. The results showed no significant difference (p>0.05) in proximate composition of the samples in the two storage facilities. Microbes isolated from the smoke-dried fish samples were Staphyloccus aureus, Bacillus subtilis and Escherichia coli. Total bacterial counts (TBC) at week 6 for C. gariepinus were 0.17×10^-6 and 0.25×10^-6; C. nigrodigitatus, 0.24×10^-6 and 0.31×10^-6 in refrigerator and kitchen cabinet, respectively, and the values were not significantly different (p>0.05) in the two storage facilities. No fungal growth was present throughout the six-week storage period. The sensory quality ratings ranged between 8.00±0.00 for flavour and 4.67±0.58 for overall acceptability. Sensory quality was significantly different (p<0.05) in flavour, texture, appearance and aroma at week 2 and 6. The findings of this study show that the storage facilities retained good nutritional and sensory qualities as well as overall acceptability of the smoke-dried fish throughout storage.