Effects of Different Processing Methods on the Proximate, Sensory, and Microbial Properties of Three Selected Ice Fish
Objectives of the Study:
The objectives of this project work were:
- To determine the proximate composition of three selected ice fish produced from different processing methods,
- To assess the sensory properties and
- To evaluate the microbial properties of selected ice fish
A fish is any member of a group of animals that consist of all gill bearing aquatic craniate animals that lack limbs with digits (Flajnik and Kasahara, 2009). Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups (Helfman et al., 2004). Tetra-pods emerged within lobe-finned fishes, so sadistically they are fish as well. However, traditionally fish are rendered obsolete or paraphyletic by excluding the tetrapods (i.e., the amphibians, reptiles, birds and mammals which all descended from within the same ancestry) (Helfman et al., 2004). Because in this manner the term “fish” is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology. The traditional term pisces (also ichthyes) is considered a typological, but not a phylogenetic classification (Nelson and Joseph, 2006).
Fish and seafood products, have a high nutritional value regarding beneficial amounts of protein, lipids as well as essential micronutrients. Aquatic animal foods are a rich source of protein and have a lower caloric density, and have a high content of omega 3 long chain polyunsaturated fatty acids (n-3 LC PUFA) compared to land living animals (Tacon and Metian, 2013). Fish and other seafood have also a well-balanced amino acid composition, contain high proportions of taurine and choline, the vitamins D3 and B12 and the minerals calcium, phosphorus, iodine, and selenium. Furthermore, fish and seafood also might provide significant proportions of vitamin A, iron, and zinc to a population if other sources of these nutrients are scarce (Lund, 2013).
Types of Fish
- White fish (such as cod, stingray, niletilipia, catfish, haddock, plaice, and snakefish e.t.c)
- Oily fish (such as salmon, trout herring, eels and Barracuda e.t.c)
- Shellfish (such as lobsters, praws, and crabs e.t.c)
History of Fish
Fish is one of the protein foods that needs careful handling (Eyo, 2004). This is because fish spoils easily after capture due to the high tropical temperature which accelerates the activities of bacteria, enzymes and chemical oxidation of fat in the fish. Due to poor handling, about 30 – 50% of fish harvested are wasted in Nigeria. These losses could be minimized by the application of proper handling, processing and preservation techniques (Bate and Bendall, 2010). Fish are normally caught in the wild. Techniques for catching fish including hand gathering, spearing, netting and trapping. Oceans help us in multiple ways and should be of everyone’s concern, not just that of researchers. They form the largest ecosystem and life support system of the Earth. Covering about 71% of the surface of this planet, oceans generate more than half of the oxygen we breathe, hold 97% of the world’s water, regulate climate, supply food and pharmaceuticals, provide millions of jobs, offer unlimited recreation, and allow trade and transport (Bokova, 2013).
The value of goods and services originating from coastal and marine environments is about $2.5 trillion each year, making oceans the seventh largest economy in the world which helps in the livelihoods of 10–12% of the world’s population (Northrop, 2018). The total asset value is estimated to be $24 trillion. Food security is a major global challenge. How much it matters is not difficult to understand from some basic facts and figures. Out of 7.6 billion people in the world, nearly 821 million are suffering from undernourishment or chronic food deprivation (FAO, 2018).
Principal Constituents of Fish Muscle
The biochemical composition of fish varies widely and these variations are determined by many factors such as biological status in the life cycle, feeding habits and environmental conditions (Gopakumar, 2002). Mazumder et al. (2008) analyzed the proximate composition of some small indigenous fish species in Bangladesh and found that the protein content varied from species to species. However, the author states that the proximate compositions of different small indigenous fish are more or equal to other larger fish species. Thammapat et al. (2010) studied proximate and fatty acids composition of the muscles and viscera of Asian catfish (Pangasius bocourti) and reported that the contents of protein, moisture and ash were inversely proportional to lipid content. Viscera had the highest lipid content followed by ventral and dorsal had the lowest. Sankar and Ramachandran (2001) reported that the proximate composition of fish depends on various factors such as sex, size, stages of maturity and season. It has also been reported that factor such as feed composition, environment, fish size, and genetic trait all have an impact on the composition and quality of aquaculture fish (Reinitz et al., 2009).
MATERIALS AND METHODS
Ice Mackerel, Herring fish and Blue whitening were purchased from the main market of Owo, they were preserved in the freezer for further processing in the Processing Laboratory, the analysis were carried out in the Chemistry Laboratory while the microbial analysis was done in the Microbiology Laboratory. The processing and all analysis were carried out in the Department of Food Science and Technology, Rufus Giwa Polytechnic, Owo
Mackerel (Titus), Herring fish (Shawa) and Blue whitening (Panla) were washed in clean water to remove dirt that was attached to the skin of the fishes, the gills and fins of the fishes were removed. The fish (Mackerel, Herring and Blue whitening) were then divided into three portions.
- The first portion was smoked, after smoking the fish (Mackerel, Herring fish and Blue whitening) were cooled and packaged in small plastic containers (Figure 3.1).
- The second portion was deep fried, after golden yellow was achieved the fish moved into plastic sieve to cool at room temperature, after cooling it (Mackerel, Herring fish and Blue whitening) was then packaged in small plastic containers (Figure 3.2).
- Lastly, the third portion was dried blankly under the sun for 1 (one) week to achieve ultimate dryness of the fish (Mackerel, Herring fish and Blue whitening), after drying the fishes were packaged in plastic containers (Figure 3.3).
RESULTS AND DISCUSSION
Table 4.1: Proximate composition of smoked, fried and dried ice fish (Mackerel, Herring Fish and Blue Whiting)
CONCLUSION AND RECOMMENDATIONS
Fishes are rich source of protein commonly consumed as an alternative source of protein due to the higher cost of meat and other sources of animal protein. The result for proximate composition of selected ice fish (mackerel, herring and blue whiting fish) preserved using three different methods (smoked, fried and dried) revealed that dried fish have the least moisture content hence indicating longer shelf life, the fibre content of the fish was observed low this is due to low fibre content of fishes although dried mackerel fish and smoked herring fish had the highest fibre content, fishes fried with vegetable oil was recorded to have the highest value of fat while sample FMF have the highest fat content. The protein and ash content was recorded highest for sample SHF and SMF (protein), the carbohydrate content was noted highest in all blue whiting fish samples. The sensory attributes revealed that fried fish samples was mostly rated and generally accepted by the judges compared to other samples. The high smoked and fried fish samples had the highest bacterial and fungal count, the low bacterial and fungal count of dried fish samples revealed that dried fish have longer shelflife due to its low moisture content.
Based on the findings in this study, it can be recommended more of fish should be consumed in our diet since it contains some essential nutrient which can help reduce malnutrition. It is also recommended that drying of fish should be practice if there is no capital to buy freezer in order to preserve fish, this will help reduce fish spoilage. And also for the enjoyment part of it, frying and smoking can help improve the organoleptic properties of fish which the consumer will find more palatable to consume.
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