International Journal of Aquaculture, 2025, Vol.15, No.1, 1-10 http://www.aquapublisher.com/index.php/ija 2 developed as alternatives. Natural preservatives are available from a variety of sources including plants, animals, bacteria, algae, and fungi (Ghanbari et al., 2013; Hassoun and Coban, 2017). Microbial derived preservatives (e.g., bacteriocin), plant derived preservatives (thyme essential oil, tea polyphenols, rosemary extract, etc.), and animal derived preservatives (e.g., chitosan from crab or shrimp shells) have been demonstrated to have antimicrobial or antioxidant properties. In addition, antimicrobial compounds produced by algae and fungal (mushroom) could be served as potential sources of new antimicrobial substances for use as natural preservatives in food. Fresh fish can easily deteriorate after being captured due to the endogenous enzyme and rapid microbial growth naturally present in fish or from contamination (Jiang et al., 2018). In the process of fish decay decomposition of various components and formation of new compounds occur. What is more, changes in composition during fish decay lead to protein degradation and lipid oxidation, as well as changes in fish odor, flavor, and texture. Therefore, it has become inevitable to develop effective treatment methods to extend the shelf life of fish (Campos et al., 2012). Soft or mushy texture of fish limits the shelf life, thereby impeding its marketing. During postmortem handling and storage, the holding temperature, oxygen, endogenous or microbial proteases, moisture can result in detrimental changes in the color, odor, texture, and flavor of fish (Sriket et al., 2010). Therefore, fish have traditionally been cooled and stored in flake ice, refrigerated sea water, or ice slurries or they have been preserved by exposure to chemical agents. At the same time, the fishery industry is always looking for new preservation methods to extend the fish shelf life and provide consumers with the best quality in terms of sensory and nutritional levels (Rey et al., 2012). The study hypothesis that Moringa leaf, Ginger root and their combination could serve as bio-preservatives for smoked catfish. 2 Materials and Methods 2.1 Study area A 12weeks completely randomized design (CRD) feeding trial was conducted at the Department of Fisheries Technology, Federal Polytechnic, Ado-Ekiti, Ekiti State, Nigeria. 2.2 Procurement of fish sample A total of 8000 g of fresh African catfish (Clarias gariepinus) was procured from a reputable Fish farm and processed at the Department of Fisheries Technology, Federal Polytechnic Ado Ekiti. 2.3 preparation of moringa seed and ginger root powder Dry Moringa oleifera seed and ginger root was procured from a reputable farm and air-dried at average room temperature. They were kept away from high temperatures and direct sun light to avoid destroying active compounds. The dried Moringa seed and ginger root was grounded separately to fine powder using electric blender. 20 gramme of the powdered Moringa seed and ginger root were added to 1 liter of water to form 2 % of Moringa aqueous and ginger aqueous solution respectively (Samira et al., 2022). 2.4 Experimental design The fish were randomly assigned to four dietary experimental treatments and replicated thrice. The first treatment (T1) is the control, without extract. The second treatment (T2) was Moringa seed powder (M); Treatment (T3), ginger root powder (G); the fourth treatment (T4), mixture of two powder (M and G). Each with a concentration of 2%. The experimental design with replicate as adopted by Abdurrazzaq et al. (2019) (Table 1). The fish was later soaked in the respective solutions (M,G and mixture of MG) for 30 minutes. Table 1 Composition of experimental diets Treatments Ingredients Concentration (%) T1 (Control) Without extract - T2 Moringa seed powder extract 2.0 T3 Ginger root powder extract 2.0 T4 Mixture of Moringa seed powder and Ginger root powder 2.0
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