Effect of Different Energy Source on the Nutritional Composition and Acceptability of Clarias Gariepinus

CHAPTER ONE

1.0 INTRODUCTION

1.1 Background InformationFish  is   an  important   source of cheap   first   class   protein, providing essential   amino   acids(Aremu et al., 2014), it is an indispensable source of micronutrients (Okonji et al., 2016) andother elements for the maintenance of healthy body (Ravichandran et al., 2012; Ehigiator etal., 2015). The results of a study conducted by Sipe (2008) have shown a positive correlationbetween the amounts of fish consumed and life span of the consumer. Aremu et al. (2014)reported that majority of Nigerians, Americans and Japanese who depend on fish as theirmain source of protein have longer life span.In spite of the importance of fish and the fishing industry, fish is an extremely perishablecommodity, spoiling soon after death, due to enzymatic and microbial actions, resulting indisagreeable taste, smell and texture, thereby reducing consumer acceptability (Garrow andJames,  2004;  Emine   and   Bahri,  2015).  Various   factors   are   responsible  for  fish spoilage,notable   among   these   factors   are   fish   health   status,   the   presence   of   parasite,   bruises   andwounds on the skin and the mode by which the fish was captured (Omoruyi  et al., 2016).Aremu  et al. (2014) also asserted that high ambient temperature of the tropics are a majorenvironmental factor prompting rapid  spoilage of fish. Hence, careful handling and rapidprocessing are essential steps to overcome the problem of rapid fish spoilage.Preservation   and   processing   are   means   of   prolonging   the   shelf-life   of   fish   products   inacceptable   quality   through   changes   in   texture,   taste   and   appearance   without   adverselyaffecting the chemical nature of the product. Processing and preservation refers to some ofthe ways in which the mechanism which cause fish spoilage are slowed down or stopped(Ray, 2010). Fish processing on the other hand usually change the texture, taste, physicalappearance   of   the   fish   so   that   deterioration   is   slowed   or   halted   but   the   fish   change1

characteristics   according   to   the   process   used   (Madu,   2016).   The   main   objectives   ofprocessing fish are to prevent increase in microbial load and other enzymatic reaction andkeeping the fish in an acceptable way between the time of capture or harvest and consumption(Omoruyi and Abolagba, 2015). In order to avoid spoilage which leads inevitably to postharvest losses several methods of preservation can be employed to prolong the shelf life offish while still maintaining its nutritional, economical and physical content. They includedrying, salting, freezing, canning, smoking (Akinola et al., 2006; Omoruyi et al., 2017).Smoking of  fish   is   a   major   way of  preserving   fish   in  Nigeria. Smoking  of  fish   has   theobjective   of   preservation   basically   due   to   dehydration   and   high   temperature   of   smoking(50 – 180oc) (Omoruyi and Ebhodaghe, 2017). Bacteriostatic, bacteriocidal and antioxidantfunctions of smoke and the dehydration effect of the process were used inadvertently by theearly fish processors in the preservation of fish (Aremu et al., 2014). Although consumers aregenerally attracted by the flavour of smoke-dried fish, its nutritive value is of paramountimportant since every consumer wants to obtain good quality protein from fish consumption(Raffray et al., 2014). Acceptability of smoke-dried products however depends on the type of fuel material used(Yola  and   Timothy,   2012).  Wood   selection   must  be   done   with   care   as   some   wood   likeresinous types for example pine may impart unpleasant flavor and taste to the final product;while  others like  Euphobia species  may be poisonous (The United Nations  DevelopmentFund for Women/UNIFEM, 2008). Although many wood types may be used as fuel for fishsmoking among the many factors influencing the choice of wood, what is used depends onlocal availability.  The  fuel wood preferences of most fish smoker  are also related  to thephysical characteristics   of   the   wood   and   how they affect  the   smoked  product   (Yola   andTimothy, 2012). Different fuel material may affect the quality of the smoked fish differently