Microbiological Quality of Gadus morhua Treated With Silver Nanoparticles Synthesized Using Launaea taraxacifolia Leaves

Abstract

A number of shelf life-promoting strategies have been adopted for fish and fisheries products. The in vitro preservative effect of Ag- nanоparticles synthesized using Launaea taraxacifolia leaves on Atlantic cod fish (Gadus morhua) was investigated. The treated (TRD) fish  samples were dipped in 25% silver nanoparticles (AgNPs) preparation for 30 minutes and analyzed at four hours intervals for 24 hours.  Samples were cut into Head (H), Trunk (TR), and Tail (TL) parts and evaluated for total heterotrophic bacterial counts (THBC) and total  yeast counts (TYC) all expressed in log CFU/g. Untreated (UTD) served as control. The concentrations of silver in both treated and  untreated fish samples were determined. Data were analyzed using descriptive statistics and ANOVA at α0.05. The treated samples  recorded lower THBC values than the untreated: head (6.18±0.27 vs 6.55±0.65); trunk (6.22±0.11 vs 6.61±0.41) and tail (6.40±0.34 vs 6.57±0.83). The treated samples had lower TYC values than the untreated: head (6.34±0.58 vs 7.44±0.38), trunk (6.59±0.66 vs 7.05±0.46)  and tail (6.47±0.30 vs 6.81±0.95). Both the treated and the untreated samples were dominated by Enterococcus spp. (569 vs 957) and  Micrococcus spp. (13 vs 18). Bacillus spp. (36) was isolated only in the untreated sample. The silver concentrations were highest in untreated  and treated trunk samples respectively (1.12 and 2.13µg/g), followed by head samples (0.58 and 1.41µg/g) while the tail  samples had the least (0.27 and 0.29 µg/g). The Ag-nanоparticles synthesized from Launaea taraxacifolia leaves exhibited both  antibacterial and antifungal activities and could be useful in preserving fish and fishery products.