International Journal of Aquaculture, 2016, Vol.6, No.18, 1
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3.1 Moisture
The low observed moisture content in this study for sundried and smoked fish has been earlier reported by
Sveinsdottir (1998) attributing to the fact that smoking decreases water activity in fish tissue. The high moisture
content in fillets that were salted before sun drying or smoking agrees with Bille and Shamkai (2006) who
suggested that increase in the moisture content of salted dagga fish samples could be due to the hydroscopic
nature of Sodium chloride (NaCl) which takes up moisture from the surrounding environment also reported by
Khan and Khan (2001). Other authors (Hernandez-Herrero, 1997; Ahmed et al., 2010; Alsaban et al., 2014) also
reported reduced moisture content with salting in fish. Sundried fish would therefore exhibit better storage
properties because moisture favours microbial growth.
3.2 Protein
Protein decreased with salting in this study earlier reported by Holma and Maalekuu (2013) and Alsaban et al.
(2014) while high protein content in sundried and smoked fillets has been observed by Fapohunda and Ogunkoya
(2006). It is reported that the level of free amino acids in salted and sun dried fish decrease during storage (Smith
and Hole, 1991). High protein content in smoked fillets could be due to concentration of nutrients due to loss of
water (Doe and Olley, 1983). It is known that salt alters colloidal properties of the proteins and changes the nature
of the water/protein relationship (Alsaban et al., 2014). This is explained by the denaturation of both sacoplasmic
and myofibrillar proteins due to the effect heavy salting on fish muscle also reported by Ahmed et al. (2010). This
suggests that sundried
Rhamphochromis
species is the best source of dietary animal protein and that addition of
salt though increases shelf life compromises the nutritive value of the fish.
3.3 Energy
Results show a correlation between fat, protein and energy values in a way that energy decreased with decrease in
fat content since fats are the energy source. It also follows that the higher the protein content, the higher the
energy level (Holma and Maalekuu, 2013). The lower moisture content in sundried smoked fillets would mean
more lipids and protein and consequently higher energy density in the fish (Aberoumad and Pourshafi, 2010).
3.4 Fat
Low fat content in salted fillets could be due to physical losses that are usually necessitated by the breakdown of
tissue cells during salting, followed by the heating effect of sun-drying (Pace et al., 1989; Holma and Maalekuu,
2013). According to the Food and Culture Encyclopedia (2003), salted and sun dried fish are also more prone to
oxidation than fish preserved by other methods because of their exposure to light and oxygen. The lowest fat
content of 11.09% in the salted sundried fillets suggests that Rhamphochromis species are fatty fish because fish
are only considered as lean when fat content below 5% (Ackman, 1989). In this study, there was a correlation of
high moisture and fat content for salted fillets of which the implication would be a relatively short shelf life of the
fillets due to microbial spoilage (high water content) and lipid oxidation.
3.5 Ash
Salting increases ash content (Ahmed et al., 2010; Alsaban et al., 2014). The increase in ash content during salting
in this study may be due to the effect of extracted lipid which helps to create a crusted surface on each dried fish
(Mohammed, 2007). Addition of salt may have added more ash components to the product (Beauchamp and
Engelman, 1991). The effect of ground bones and scales in dried fillets could also have resulted into increase in
ash content (Alsaban et al., 2014).
4 Conclusion & Recommendations
Sundried
Rhamphochromis
species is rich in protein - the most sought after nutrient in fish but also a fatty fish.
Results further suggest that consumers would have a more nutritive product by avoiding adding salt to
Rhamphochromis
fillets but rather sun drying and smoking. The lowest moisture content in sundried and smoked
fillets also suggest a processed product with a longer shelf life as moisture favours microbial growth that are
responsible for most spoilage in fresh foods. It was observed that processing method (sun drying then smoking)
