Effect of Stunning Methods on the Proximate Composition and Organoleptic Properties of Fresh and Smoke-Dried Catfish (Clarias gariepinus)
Abstract
Stunning is a critical step in fish processing that immobilizes fish before slaughter. This study investigated the effect of different stunning methods on the proximate composition and organoleptic properties of fresh and smoke-dried catfish. A total number of 20 live catfish (Clarias gariepinus) with a mean weight of 0.84±0.03 kg were obtained from a fish farm and were stunned by salting, icing, hammering, and exsanguination methods. Proximate analysis was carried out on parts of the freshly stunned fish. The rest of the fish samples were smoked dried, and then subjected to proximate analysis and organoleptic properties evaluation. The result of the organoleptic properties evaluation revealed that fish stunned by Salting (9.4±0.52) were the most preferred, while those stunned by icing (8.8±0.79) were the least preferred with no significant difference in overall acceptability among the stunning methods. The proximate analysis of fish samples showed that stunning methods had varying impacts on the proximate composition of fresh and smoke-dried fish samples. Fresh fish samples stunned by icing had the highest protein content (33.95±0.49) with the lowest moisture content (39.48±3.97), while the hammering method had the lowest protein content (19.25±0.49) with the highest moisture content (51.11±0.77). Smoke-dried fish samples stunned by icing method had the highest protein content (64.23±0.74), fat content (17.91±3.01) with a moisture content of 4.01±0.55, while the Salting method had the lowest protein content (54.78±0.74), and highest fat content (19.44±3.08) with a moisture content of 4.21±0.66. This study revealed that smoke drying improved the nutritional composition of catfish across all stunning methods.
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Introduction
Fish is consistently among the most used and cheap dietary sources of animal protein for most people worldwide (Allam et al., 2020; Maulu et al., 2020). It is a valuable source of essential nutrients, especially high-quality protein and fats (macronutrients), vitamins, and minerals (micronutrients) that make a vital contribution to the world's food and nutrition security (FAO, 2020). As a food product, fish is of greater importance in developing countries where it accounts for 75% of the daily animal protein, referred to as “rich and poor food” as an important companion (Willett et al., 2019; Mansour, 2021). It is readily available even in poorer communities at a relatively cheaper price than other animal protein sources. Furthermore, fish production through aquaculture is considered sustainable and the most efficient way to produce high-quality proteins for human consumption (Ali et al., 2021; Khalil et al., 2021).
The African catfish (Clarias gariepinus) is a significant fish species cultured in Africa. It has also been introduced into aquaculture in different parts of the world. It is primarily freshwater fish that are well adapted to confined environments and are resistant to manipulation and disease. Catfish are highly nutritious, containing a high concentration of unsaturated fatty acids, vitamins, proteins, and minerals (Nelson et al., 2016). Since dietary composition is a significant determinant of the nutritional quality of fish flesh, numerous reports are available on African catfish slaughter traits and fillet quality (Sándor et al., 2022). Recently, farmed fish have been subjected to various stunning techniques while processing. Many of these methods are assumed to present welfare problems since they expose fish to prolonged suffering and pain before death (WOAH, 2022).
Conclusion
In conclusion, this study evaluated the effect of different stunning methods on catfish's nutritional composition and organoleptic properties. The findings showed that each stunning method had unique effects on the nutritional composition of fish. Stunning methods of Hammering may be considered effective and humane since they exert little stress, pain, and struggle on the fish. In organoleptic evaluation, the salting method may be considered the best stunning method compared to other methods. Smoking may be a means of improving the nutritional composition of catfish since the proximate composition of the fish was improved after smoke-drying. The impact of stunning methods on fish quality highlighted the importance of considering nutritional factors, food safety concerns, and consumer preferences in fish stunning, processing, and storage. By understanding the effects of different stunning and processing techniques on fish quality, producers can make proper decisions to meet consumers' diverse needs and expectations. The choice of stunning method should be considered based on the desired nutritional profile and the intended use of fish products because of its significant impact on the quality and freshness of fish samples.
Further research and evaluation of stunning methods are important for ensuring fish quality and safety throughout the supply chain. Fish producers should avoid stunning methods that are considered inhumane since they affect the quality and safety of the fish's final product. Fish producers should also consider fish quality and safety, nutritional composition, and consumer preference before choosing the stunning, processing, and storage methods to maintain the quality of fish products. Using salt to stun catfish is highly recommended since it improves the fish's organoleptic properties (it adds to its taste and serves as a cleansing agent) and is a preservative. It is also recommended that farmed catfish should be smoked before consumption to obtain maximum nutritional benefit.