Application of ZnO Nanoparticles Phycosynthesized with Ulva fasciata Extract for Preserving Peeled Shrimp Quality.

Zinc oxide nanoparticles (ZnONPs) were the targets of numerous biological syntheses to attain their precious values in various biomedical fields. The phycosynthesis of ZnONPs were innovatively investigated using cell-free extract of the macroalgae, Ulva fasciata Delile. The phycosynthesized U. fasciata-zinc oxide nanoparticles (UFD-ZnONPs) had 77.81 nm mean size, with flower and sphere shapes and positive zeta potential. The UFD-ZnONPs infra-red analysis indicated their basic components' cross-linkage. The antibacterial potentialities of UFD-ZnONPs were confirmed, qualitatively and quantitatively, against foodborne microorganisms (Escherichia coli plus Staphylococcus aureus); the bactericidal action was higher for UFD-ZnONPs than the annealed phycosynthesized ZnONPs. The scanning micrographs of S. aureus and E. coli cells treated with UFD-ZnONPs indicated the severe action of nanoparticles to destroy bacterial cells in time-dependent manners. Peeled shrimps (Fenneropenaeus indicus) were biopreservated through refrigerated storage (4 °C) with UFD-ZnONPs based solution for six days. The microbial examination of UFD-ZnONPs -treated shrimps displayed decrease in microbial loads throughout the storage days. Moreover, the UFD-ZnONPs-treated shrimps showed acceptable sensorial attributes (appearance, odor, color and texture) compared to untreated shrimps. UFD-ZnONPs nanocomposite concentration of 3% and 5% could be remarkably suggested as efficient procedure for shrimps' biopreservation during refrigerated storage regarding sensorial quality and microbial profile of product.

Fungal chitosan and Lycium barbarum extract as anti-Listeria and quality preservatives in minced catfish.

Listeria monocytogenes is a foodborne bacterial pathogen that causes serious health risks. Chitosan (Ch) is a bioactive polymer that could be effectively applied for foodstuffs biopreservation. Lycium barbarum (Goji berry) is ethnopharmaceutical fruit that have diverse health protecting benefits. Chitosan was produced from A. niger and employed with L. barbarum extract (LBE) as blends for Listeria control and quality biopreservation of African catfish mince (Clarias gariepinus). Chitosan could utterly control L. monocytogenes survival in fish mince and its efficacy was strengthened with added LBE at 0.2 and 0.4%. Blending of fish mince with Ch could effectively reduce the progress of chemical spoilage parameters and this protective effect was greatly enhanced with increased addition of LBE. The sensorial assessment of treated minces indicated panelists preferences for the entire attributes of blended samples with Ch and LBE, particularly with storage prolongation. Scanning micrographs elucidated the antibacterial action of Ch against L. monocytogenes. Results recommended the application of fungal Ch/LBE composites as biopreservatives and anti-listerial agents, through their blending with catfish mince, to eliminate bacterial growth, enhance sensory and storage attributes of preserved fish.

Application of fungal chitosan incorporated with pomegranate peel extract as edible coating for microbiological, chemical and sensorial quality enhancement of Nile tilapia fillets.

Fish are generous sources for providing man with his essential nutritional requirements, but the extreme susceptibility to quality deterioration hinders their optimal usage and storage. Natural derivatives are always the perfect alternatives for food preservation. The application of fungal chitosan (Ch), from Aspergillus niger, and pomegranate peel extract (PPE), in coating films for Nile tilapia (Oreochromis niloticus) fillets preservation and maintaining their microbiological, chemical and sensorial quality during cooled storage at 4°C for 30days, was investigated. Fish fillet were coated with Ch (2%) and combined Ch+PPE, at PPE percentages of 0.5, 1.0, 1.5 and 2.0%. Fillets coating resulted in sharp decrease of the entire microbial counts during storage; the increased concentrations from PPE strengthened coating film antimicrobial activity. Additionally, fillets coating could retard the chemical spoilage parameters increasing, i.e. nitrogen volatile base (TVB-N), peroxide value (PV) and reactive substances of thiobarbituric acid (TBARS), during storage period. The sensory evaluation indicated higher preferences for the odor, texture, color and overall quality of coated samples. Fish fillets coating with Ch and Ch+PPE could be recommended for shelf life extension and maintaining the microbiological, chemical and sensorial quality through the application of safe preservatives from natural origins.