Effect of Natural Preservative (Cinnamon Bark Marinade) on the Microbial Load and Shelf-life of Smoked-dried African Catfish Clarias gariepinus (Burchell, 1822)

Introduction

Fish is a significant source of protein, and the harvesting, handling, processing, and distribution of fish support the livelihoods of millions of people. It is the most significant animal dietary protein that is currently produced and accounts for around 17.1% of all animal protein consumed worldwide [1]. Due to its high level of long-chain polyunsaturated fatty acids (LCPUFAs), which are linked to reducing aging-related diseases and enhancing health [2]. Fish is viewed as a healthier beef alternative. Fish makes over 40% of the animal protein consumed in Nigeria. In fact, Adedeji FA, et al. [3] found that consumers eat between

30 and 80 percent of their annual protein intake from fish, whether it be fresh or cured. Fish is a particularly essential source of protein in areas with a limited supply of livestock. The African catfish, Clarias gariepinus, remains the most farmed, smoked-dried and favoured catfish species in Africa and is of major economic importance among aquaculture species in Nigeria.

Post-harvest losses account for an estimated 40% of all fish landings in Nigeria [4]. The inadequate handling, preservation, and processing methods used by artisanal fisherman, fish farms, and fisheries entrepreneurs are thought to be the reason that 20 to 50 percent of the fish produced in isolated coastal areas and many tropical nations perish before they reach customers [5]. Additionally, significant- quality is lost in many tropical nations because there is insufficient equipment and knowledge to stop losses [6]. According to Hussain MA, et al. [7], food spoiling is a change in the nutritional and sensory qualities of food that renders it unpalatable to customers. Large amounts of locally produced fish are lost due to post-harvest losses, which can include everything from bacterial and autolytic spoilage to other reasons, despite the fact that local fish production is unable to keep up with the matching demand [8]. These elements make fish less organoleptically pleasing and usually unfit for human eating. To protect fish resources, it is essential to use a variety of preservation techniques, including as drying, smoking, freezing, chilling, and brining. Food preservation is required because of the world’s expanding population and the necessity to move and store food from one location to another. To extend the product’s shelf life while preserving its flavour, texture, and nutritional value. In order to preserve food without compromising its quality or nutritional content, it must be protected from microbial deterioration [9].

In general, synthetic preservation techniques and methods, such as the use of pesticides, are frequently substituted for natural preservation techniques and methods because they have been shown to have negative health effects on the final consumers of such fish, including cancer and lung issues [8]. Cinnamon is one of the natural spices frequently used in food preservation. Several trees belonging to the genus Cinnamomum produce the spice known as cinnamon, which is used in both savoury and sweet dishes [10].

Cinnamon is the quill-shaped brown bark of the cinnamon tree, which is used to make cinnamon, rolls into a tubular shape when dried. The two forms of cinnamon are entire quills (cinnamon sticks) and crushed powder. The two most popular types ingested are Cinnamonum aromaticum (Chinese cinnamon) and Cinnamon zeylanicum (Ceylon cinnamon), despite the fact that there are around 100 different variations of Cinnamomum verum, the technical name for cinnamon. The Chinese variety is referred to as “Cassia,” but Ceylon cinnamon is also known as “true cinnamon.” Although they are both quite similar in appearance and have a fragrant, sweet, and toasty smell, the Ceylon variety has a more complex and nuanced flavour. In order to ascertain the effects of cinnamon bark marinade (Cinnamomum verum), this investigation was conducted. This study was therefore carried out to determine the Preservative effects of Cinnamon Bark Marinade (Cinnamomum verum) on the microbial load and shelf life of African catfish (Clarias gariepinus).

Fish Preparation

The fish were killed by striking the spinal cord, gutting using a sharp knife by cutting laterally from the end of the gill cover through the belly portion to the anus. Thereafter was thoroughly washed and rinsed. The total length (ranging from 22-27 cm) and weight of the fish were noted after gutting.

Results and Discussion

Tables 1 show the findings of the initial smoke-dried fish samples for microbial load. It demonstrates that freshly caught fish treated with 5g of cinnamon bark powder (0.5% marinade) had the highest bacterial population, at 76x103, followed by fish treated with 1.5% of cinnamon bark marinade, at 10x103, and the lowest bacterial population, at 7x103, in a sample treated with 1.0% cinnamon bark marinade. In contrast to fish species, Chatreman N, et al. [15] found that the bacterial flora of freshly caught fish is influenced by the environment in which it was caught. This figure is likewise under the 5x105 colony forming unit per gramme suggested maximum bacteria level for high-quality fish products according to ICMSF [16] and the microbiological guidelines. For Ready to-eat-food which is <106 (Microbiological Guideline for Ready to-Eat-Food).

Mean value with the same letter in a row are not significantly different (p>0.05) Table 1: Mean value of microbial population (cfu/g x103) on fish smoked with different marinade of cinnamon bark.

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Immediately after smoke drying, Corynebacteria species, Bacillus subtilis, and Staphylococcus albus were the bacteria that could be isolated from sample 0.0% marinade. Bacillus subtilis, Staphylococcus albus, and Corynebacteria were present in the sample 0.5% marinade, Bacillus subtilis was present in the sample 1.0% marinade, and Corynebacteria specie was present in the sample 1.5% marinade. Prior to storage, the total bacteria frequency and percentage for the smoked-dried fish samples of 0.0%, 0.5%, 1.0%, and 1.5% were 30, 30, 20, and 20 respectively (Figure 4).

In comparison to the untreated fish samples (Control), there was a reduction in bacterial loads at all doses of the cinnamon bark marinade (Table 2). Bacillus subtilis, Corynebacteria species, and Staphylococcus albus were among the many bacterial species that were isolated and identified. The smoked fish may have become infected by these microbes through soil, air, or human handling. According to Mahmud A, et al. [17], the presence of this microorganism in samples of smoked fish may be caused by a rise in the product’s moisture content during storage as well as an increase in temperature, both of which encourage the growth of these organisms. When handling fish, organisms linked to humans, such as Staphylococcus aureus and members of the Enterobacteraceae family, which thrive around 30-70°C, will infect the fish’s natural flora. According to Danba EP, et al. [18], Staphylococcus is one of the most common microorganisms associated with smoked fish, and Inusa M, et al. [19] speculate that the presence of this bacteria (Staphylococcus albus) in fish samples may have been caused by handling. Because Staphylococcus albus has been linked to food borne illness and infection, its presence has no bearing on public health. The effect of pathogenic bacteria Chatreman N, et al. [15] can be attributed to its capacity to create enzymes and poisons. The smoked fish must have come into contact with this organism through human handlers. Food-borne disease may also occur from the presence of Bacillus species.

Table 3 displays the changes in microbial load of products made from smoked fish during storage at room temperature for a period of twenty-eight (28) days. This data is consistent with studies by Chatreman N, et al. [15], who indicated that cinnamon verum blume bark extract is a well- known anti-microbial agent. The population of bacteria in the smoked fish product increased significantly after 7 days of storage. Fish sample treated with 0.0% cinnamon bark marinade had the highest rise (150x103 cfu/g), followed by fish sample treated with 1.5% cinnamon bark marinade (71x103 cfu/g). Bacterial population starts to decline after 14 days of storage and keeps falling. The lowest 15x103cfu/g

bacterial population was seen in fish product treated with a 1.5% cinnamon marinade after twenty-eight (28) days. There were significant variations (p< 0.05) among the samples.

Mean value with the same letter in a Column are not significantly different (p>0.05) Table 3: Changes in Microbial loads (populations (cfu/g x103) of smoke fish after Smoking with different concentration of Cinnamon bark marinade stored at room temperatures

Conclusion and Recommendation

The study’s findings demonstrated that smoke-drying and spicing had a substantial impact on the fish samples’ microbial population and shelf life dynamics. The study found that all three smoked-dried fish sample treatments (0.5%, 1.0%, and 1.5% Cinnamon bark marinade) had a comparatively low bacterial count, indicating that the effects of smoke-drying and spicing with Cinnamon Bark marinade lowered the growth level of microorganisms. In fish that had been marinated in a 0.5% solution, the number of microbes had increased. The rise was noticeable in the control sample, though. The marinade made with 1% bark had the strongest antibacterial impact. Compared to other samples, the control samples showed a more varied microbiota. The sample that was marinated in a 1.5% cinnamon bark solution demonstrates the ability of bacteria to proliferate.

Farmers are encouraged to use this spice preparation and incorporate it into fish before smoking since it has antibacterial and antimicrobial characteristics in addition to acting as a preservative and enhancing nutrition. The microbial load of smoke-dried catfish held at room temperature for up to a month might be controlled using a cinnamon bark marinade. This would significantly improve food safety and security by extending shelf life, decreasing fish deterioration, particularly that caused by bacteria, and shielding customers from foodborne illnesses. To ascertain the impact of it oil on the microbiological stability of smoke- dried catfish held for a longer period of time at room temperature, another research might be conducted.

Conflict of Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funding Information This study involved no external funding.

Author’s Contribution Conceptualization MYH, and MMB; Investigation MYH and MMB; Project administration MYH, Methodology, MMB and MYH; Formal Analysis, MYH; Supervision MMB; Writing – Original Draft Preparation MYH; Writing-Review & Editing MYH, AIA, MI and MS. All authors were involved in critical interpretation of the data, manuscript revision, and final version approval.

Acknowledgements

The authors wish to thank the Department of Fisheries, University of Maiduguri, Nigeria for using their facilities. We appreciate the technical assistance for the Teaching and Research Farm staff of the department.