Control of microbiological quality and shelf‐life of catfish (Clarias gariepinus) by chemical preservatives and smoking

Abstract

Fresh catfish (Clarias gariepinus) were subjected to different concentrations of sodium benzoate or potasium sorbate and smoked traditionally before evaluation for microbiological, chemical and organoleptic characteristics during ambient tropical storage. Unsmoked fish samples showed diverse microflora (Enterobacter, Escherichia, Serratia, Bacillus, Staphylococcus, Streptococcus, Penicillium, Aspergillus and Achlya genera) while smoked samples were dominated by Gram-positive bacterial flora (Bacillus, Staphylococcus and Streptococcus) and spoilage moulds (Penicillium verrucosum, Aspergillus flavus and Achlya spp.). Significant reduction in microbial population occurred in most samples following smoking with samples subjected to 0.4% (w/v) potassium sorbate showing the lowest microbial load and maximum shelf-stability. However, marked microbial increase occurred after day 4 of storage in control and benzoate-treated samples. Changes in pH were marginal but decreased after day 12 of storage. Moisture content decreased sharply after smoking and remained low after day 4 of storage. Overall, potassium sorbate treatment (0.4% w/v) was most effective in controlling microbial quality and extended the shelf-life of the samples by 8 d.

Utilisation of antimicrobial agents at pre- and post-smoking on the microbial quality of hot-smoked rainbow trout(Oncorhynchus mykiss)fillets

“…This result demonstrated that PS was more effective against the propagating microfl ora during storage. PS provides the best bacterial inhibition of microbial growth in smoked trout fi llets during refrigerated storage, as observed by others (EFIUVWEVWERE & AJIBOYE, 1996;OMOJOWO et al, 2009). The most important feature that emphasizes the use of sorbate as a preservative is the continuous antimicrobial effect of this agent at neutral pH values (LÜCK, 1990).…”

“…In order to diminish safety risks and prevent economic losses, using safe preservatives in fi shery products has been recommended. In the preparation of smoked catfi sh, carp, and salmon, different concentrations of PS and SL have been used as preservatives (EFIUVWEVWERE & AJIBOYE, 1996;NYKÄNEN et al, 2000;ÖKSÜZTEPE & GÜREL-INANLI, 2007;DA SILVA et al, 2008;OMOJOWO et al, 2009). In most preservative-based strategies, the effi cient inhibition of microorganisms has been achieved at 3% concentrations of PS, SL, or sodium metabisulfi te (DA SILVA et al, 2008;OMOJOWO et al, 2009), which has been also accepted as GRAS status by Food and Drug Administration (FDA).…”

Preservation of Fish by Curing

“…Smoking usually extends the shelf life of fish due to the combination effects of (i) salting, which lowers water activity resulting in reduced microbial growth, (ii) elevated temperature drying, which provides a physical surface barrier to the passage of microorganisms, and (iii) deposition of antimicrobial and antioxidant compounds, such as aldehydes, carboxylic acid and phenols, which delays microbial growth and rancidity development (Efiuvwevwere and Ajiboye, 1996;Leroi and Joffraud, 2000). Moreover, fish muscle exposed to smoke in combination with a high temperature can effectively limit harmful enzymatic reactions (FAO, 1992).…”

Combined effect of lime (Citrus aurantitolia) and drying on reducing bacteria of public health significance in Edible Oyster (Crassostrea madrasensis)

“…Various food preservation techniques have been utilized to improve the microbial safety and extend the shelf life of seafoods in general, including freezing, chemical preservation, salting, and smoking (Jay 1998;Nickelson et al 2001;Wood 1981). Smoking usually extends shelf life of fish due to the reduced moisture content and the effects of imparted phenolic compounds (Efiuvwevwere and Ajiboye 1996). Another shelf life promoting strategy involves salting with NaCl or with chemical preservatives.…”