ABSTRACT
This study designed, fabricated and evaluated drying performance of a solar fish dryer. Fish samples (225g each) were processed using open sun drying (CCC), fabricated solar dryer (BBB) and smoke drying (DDD). The unprocessed sample (AAA) served as the control. Samples were randomly assigned to the three (3) drying methods and replicated twice. Samples were analyzed for proximate, microbiological, physiochemical, vitamins and mineral composition, using standard labouratory procedures. Data were also collected for organoleptic properties. Data obtained were subjected to the analysis of variance. Decrease in moisture content was observed during processing using the various drying methods until samples attained constant weight within 40-64hours. The proximate composition of the fish samples were significantly (p≤0.05) affected by the different drying methods. Moisture ranged from 10.05-40.95%, indicating potentials for storage stability for sample BBB and CCC. Carbohydrate, Crude fibre and ash were generally low while protein and fat were high ranging from 37.48%-55.61% and 16.20%-30.30% respectively. AAA and CCC showed significantly (p≤0.05) higher microbial load on both the nutrient agar and macConkey agar. pH of samples was not significantly (p≤0.05) affected by drying methods. The free fatty acid and peroxide values of the samples ranged from 1.38-5.02Mg/KOH/g and 1.10-2.90Mg/Kg respectively. These were generally higher in CCC, indicating its potency to develop off flavor. The different processors used significantly (p≤0.05) affected the level of acceptability of the samples by the panelists. DDD recorded the highest level of acceptance among the samples, followed by BBB, CCC and AAA respectively.
TABLE OF CONTENTS
Page
Title
page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Table
of Content vi
List
of Tables xi
List
of Figures xii
List
of Plate xiii
Abstract xiv
CHAPTER
1: INTRODUCTION
1.1 Background of Study 1
1.2 Statement of Problem 6
1.3 Justification 6
1.4 Objective of Study 7
CHAPTER 2:
LITERATURE REVIEW
2.1 Fish 9
2.1.1 Group
of fishes 11
2.1.2
Types of fishes 12
2.1.2.1
Common carp 12
2.1.2.2
Atlantic cod 12
2.1.2.3
African catfish 13
2.1.2.4
Atlantic mackerel 13
2.1.2.5
Tilapia fish 13
2.1.2.6
Bony fish 14
2.1.2.7
Salmon fish 14
2.1.3
Sources and origin of common Fishes 14
2.1.4
Fish cultivation in Africa 15
2.2 Fish Spoilage
and Causes 17
2.2.1 Post harvest fish losses 17
2.2.2
Autolysis 18
2.2.3 Bacteria 19
2.2.4 Rancidity 21
2.2.5 Mechanical damage 21
2.3 Methods of Fish Preservation 21
2.3.1 Salting 23
2.3.2 Cold storage
method of fish preservation 23
2.3.3 Frying
method of fish preservation 25
2.3.4 Canning
method of fish preservation 26
2.4 conventional
Drying Methods 27
2.5 Drying
Methodology 28
2.5.1
Natural drying methods 29
2.5.1.1 Direct method 30
2.5.1.2 Indirect method 31
2.5.1.3 Green house solar dryer 32
2.5.2 Artificial drying methods 33
2.5.2.1 Convective drying 33
2.5.2.2 Drying by radiation 34
2.5.2.2 Freeze drying 34
2.5.2.3 Osmotic drying 36
2.6 Quality Loss of Traditionally
Dried Fish 37
2.7 Drying
Kinetics and Modelling 38
2.7.1 Effect of air temperature and
air velocity on drying kinetics 40
2.7.2 Effect of shape on drying
kinetics 41
2.7.3 Effect of pre-treatment on
drying kinetics 42
2.7.4 Effect of relative humidity on
drying kinetics 43
2.8 Commercial Dried Products 44
2.8.1 Dried meat products 44
2.8.2 Powdered products 45
2.8.3 Drying of cereals and pulses 46
2.8.4 Dried cultures 46
2.8.5 Dried fruits and vegetables 47
2.9 Effect of Smoking Methods on
Quality of Fish 47
2.9.1 Hot smoke 50
2.9.2 Open fire smoking 52
2.9.3 Cold smoking 52
2.11 Effects of sun and oven drying
on fish 53
CHAPTER
3: MATERIALS AND METHODS
3.1 Materials 54
3.2 Methods 54
3.2.1 Construction of the solar dryer 54
3.2.1.1
Drying chamber 55
3.2.1.2 Cover
plate 55
3.2.1.3 Cover
55
3.2.1.4 Air
gap (inlet and outlet) 55
3.2.1.5 Drying
tray 55
3.2.1.6 Orientation
of solar collector (glass) 56
3.2.1.7 Angle
of tilt of solar collector 56
3.2
Expected Heat Flux that will be generated by the Fabricated Dryer 57
3.2.1 Minimum
expected heat flux that will be generated by the dryer
within 57
3.2.2 Maximum
expected heat flux that will be generated by the dryer 58
3.2.3 Average
expected heat flux that will be generated by the dryer
within
Umuahia region 59
3.3
Performance Evaluation of the Solar Dryer
59
3.3.1
Conventional open sun dried fishes 59
3.3.2
Drying of the fish with fabricated solar dyer 59
3.3.3
Smoking of fish 59
3.4
Determination of Proximate Composition 60
3.4.1 Determination of moisture content 60
3.4.2 Determination of ash content 60
3.4.3 Determination of fat content 61
3.4.4 Determination of protein content 61
3.4.5
Determination of crude fiber content 62
3.4.6
Determination of carbohydrate content 62
3.5
Determination of Physicochemical
Properties 63
3.5.1
pH determination 63
3.5.2
Peroxide values 63
3.5.3
Determination of free fatty acid content 64
3.6
Sensory Evaluation 64
3.7
Microbiological Determination 65
3.8
Determination of Vitamin Composition 65
3.8.1
Vitamin B1 (thiamin) determination 66
3.8.2
Vitamin A (retinol) determination 66
3.8.3
Vitamin C determination 66
3.9
Determination of Mineral Composition 67
3.10
Statistical Analysis 68
CHAPTER
4: RESULTS AND DISCUSSIONS
4.1 Drying Characteristics
of Fish Samples 69
4.2
Proximate Composition of Fish Samples 73
4.3
Physicochemical Properties 78
4.4
Microbiological Quality 81
4.5
Vitamin Composition 83
4.6
Mineral Composition 85
4.7
Sensory Quality of Fresh and Processed Fish Samples 87
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 90
5.2 Recommendations 90
References 91
Appendix 99
LIST
OF TABLES
4.1 Drying characteristics of fish samples 70
4.2 Proximate Composition of Fresh and Dried Fish Sample 77
4.3 Physiochemical Properties of Fresh and Dried Fish Sample 80
4.4 Total Plate Count (CFU/g) of Fresh and Dried Fish Sample 82
4.5 Vitamin Composition of Fresh and
Processed Fish Sample 84
4.6 Mineral Composition of Fresh and
Processed Fish Sample 86
LIST
OF FIGURES
3.1 One Chamber Cabinet Solar Dryer 57
4.1 Drying Curve 72
4.7 Mean Sensory Properties Scores of the Fish Samples 88
LIST OF PLATES
1:
Photo of Fabricated Dryer 89
CHAPTER 1
INTRODUCTION
1.1
BACKGROUND OF STUDY
Fish is a nutritious source of food of high quality
protein often cheaper than meat though highly susceptible to deterioration
without any preservative or processing measures (Okonta and Elkelemu, 2005).
They are aquatic, craniate, gill-bearing
animals that lack limbs with digits.
Included in this definition are the living hagfish, lampreys,
and cartilaginous and bony
fish as well as various extinct related groups. Around
99% of living fish species are ray-finned fish, belonging to the class Actinopterygii,
with over 95% belonging to the teleost subgrouping
(Weinmann et al., 2017).
Due to their chemical composition, fish muscle is
perishable and its flavour and texture change rapidly after harvest and during
storage. Harvesting, handling, processing and distribution provide livelihood
for millions of people as well as providing foreign exchange to many countries
(Al-Jufaili and Opara, 2006).
Preservation and processing therefore become important
part of industrial fisheries. They are done in such a manner that the fishes
retain their freshness for a long time, with a minimum loss of flavour, taste,
odor and nutritive values. Freshness of fish is usually judged entirely in
trade by its appearance, odor and texture of the raw fish. These assessments
depend upon the senses, known as sensory or organoleptic evaluation (Sengar et al., 2012).
There are so many incidents of fish spoilage across
the world, particularly in the tropics, which encourage microbial activities
and chemical changes, with resultant fish deterioration and spoilage (Dalgaard et al., 2016). The spoilage process starts
within 12 hours of their catch in the high ambient temperatures of the tropics.
Rigor mortis is the process through which fish loses its flexibility due to
stiffening of fish muscles after a few hours of its death (Ojutiku et al., 2009). Processing and
preservation methods have been considered and used to prevent fish from
spoilage. Fish is a low acid food that
supports growth of pathogens if not carefully handled and rapidly processed
after harvest (Adebowale et al., 2013).
Effiong and Fakunle (2011) reported that the decomposition or spoilage of fish
flesh occurs mainly due to various chemical, microbial and the enzymatic
actions. In Nigeria, the hot climatic condition favours rapid growth of
bacteria and so the spoilage of fish flesh becomes inevitable. Landed fishes
may ordinarily remain fresh for not more than 8hours and begin to decompose
rapidly leading to post harvest losses (Haruna, 2003). Post-harvest losses in
fish occur in various forms, namely physical, economical, and nutritional
losses. The physical losses are caused by poor handling and preservation or the
discarding of fingerlings. Economic losses occur when spoilage of fish results
in a value decrease or when there is a need to reprocess cured fish; to raise
the cost of the finished product, inadequate handling and processing methods
can reduce nutrients leading to nutritional loss (Effiong and Fakunle, 2011).
Preservative methods such as salting, fermenting, drying, and smoking are still
widely accepted around the world because of their specific taste and aroma.
However, these methods still differ from country to country and within each
country in the amount of additives, percentage of salt or vinegar and maturing
temperature (FAO, 2016).
Fish
are regarded as a good source of protein, vitamins and minerals in the diet of
people in many parts of the world including Asia and Europe. This is
particularly true for the poor for whom it is the most cost-effective animal
protein source. It was reported that amino acid composition of dried fish was
of higher quality than that of eggs (Srivastava, 2015; Jonsson et al., 2017).
Besides these, dried fish has considerably longer shelf life and requires no
refrigeration facilities for storage (Immaculate et al., 2013). Due to
these multitude of benefits, global resource utilization for processing of
dried fish is considerably high, estimated to be 8% of the total world catch
(Patterson et al., 2018). In this regard, livelihood activities of
millions of fishermen, dried fish producer, wholesalers and retailers are
directly connected to processing and marketing of dried fish (Nayeem et al.,
2010a; Nath et al., 2013). It is particularly true for people in the
marine sector engaged in the capture of fish where they are linked to
traditional processing of dried fish (Reza et al., 2012). These
activities in sun-dried fish processing and marketing are closely related to
fisheries and aquaculture sectors and thereby play important role in
employment, livelihood and economic opportunity for millions of people
throughout the globe. Among the dried fish producing countries, these
activities hold great importance for Nigeria as more than 17 million people
including 1.4 million women depend on fisheries and aquaculture related
activities such as fishing, farming, fish handling, and processing (BFTI, 2016;
DoF, 2018).
Drying
is a commonly accepted method of fish preservation with sun drying being the
most widely practiced method throughout the world. Sun dying is also one of the
world’s oldest known preservation methods (Govindan, 2017; Reza et al., 2012;
Mansur et al., 2013). Sun drying alone, or in combination with salting,
result in fish that are highly relished by people who prefer the characteristic
flavour, taste and texture (Anon, 2012).
The advancement of sun drying is solar drying systems
in which products are dried in a closed system with the inside temperature
higher than the outside (Rajkumar, 2012). Solar drying is one of the most efficient
and cost-effective, renewable, and sustainable technologies to conserve
agricultural products in Asian and sub-Saharan African (SSA) countries. In
addition, the pre-eminent effects of their use on product quality, as well as
their economic, environmental, and social impacts are acknowledged.
Solar dryers are beneficial than the sun drying
techniques. However, solar dryers do have shortcomings. They are of little use
during cloudy weather. During fair weather they can work well. Although, solar
dryers involve an initial expense, they produce better looking, better tasting,
and more nutritious foods, enhancing both their food value -and their
marketability. They also are faster, safer, and more efficient than traditional
sun drying techniques. Drying in the sun and in the open air is still the most
commonly used method of preserving and processing agricultural products. However,
uncontrolled drying suffers from severe dust problems caused by wind, insect
infestation (Mujumdar, 2011), which could lead to gross contamination.
Fish smoking in the tropics is conducted in smoke
houses, ovens or kilns with varying equipment and designs from place to place.
They are categorically classified into traditional, improved traditional and
mechanical smoking kilns. Some smoking kilns used in various localities include
coal–pot kiln, whole drum kiln, Box kiln, Chorkor oven, and smoking platform
(Oyeleye, 2003). In hot smoking, temperature may be between 60-1100C
for 4-12 hours to eliminate spoilage by bacteria. Fish are laid in trays or
hung in the column of smoke air above the fire (Egbal et al., 2010).
The Chorkor smoker oven is gaining acceptance in
traditional fish smoking. The design base has a long life, low construction
cost, and low firewood consumption. Smoking of fish could also be achieved with
pit oven, mud kiln, and drum smoking kiln with a simple smoking rack earthen
wave pot. However, the structures and the types of the smoking kilns vary from
place to place. Improved smoking kiln equipment include Futy improved kiln,
Altona smoking types of ovens and inners walker smokers. Efforts to improve the
kilns and driers designs have in general been successful and have been
introduced to small scale fish processors (Effiong and Fakunle, 2011).
A large quantity of fish is lost after harvesting,
which is due to hot weather, low levels of post-harvest technologies and poor
handling methods (Egbal et al., 2010)
Fish is a highly perishable commodity and undergoes spoilage as soon as it
lands. Spoilage occur before, during, and after processing or preservation and
the odor, flavor, texture, color, composition and nutritive value changes in
light of spoilage. The idea of fish processing and preservation is adopted to
reduce post-harvest losses. The available drying methods currently in use lack
information on the best among the three (smoking, direct sundrying and the
fabricated solar dryer). Therefore, this study is designed to bridge such
information gap. The aim of this study is to fabricate and evaluate comparatively
the performance of a solar fish dryer with two other (smoking and direct
sundrying) processing methods.
1.2 STATEMENT OF PROBLEM
The objective of improving an indigenous system is to
achieve a more sanitary and hygienic system, as well as a system for achieving technical
efficiency in time, energy, labor and material use while focusing on improved
product quality.
Dry fishes in Nigeria are either smoked or dried
artificially using electricity or naturally in the open sun. Most open sun
dried and smoked fishes are contaminated and have short shelf life. Fish
smoking causes pollution and deforestation while artificial drying depends on
electricity which is not cost effective and most often not available in the
hinterland where fish are caught and processed. Solar drying is an alternative
cost effective, hygienic and readily available dying method that is most
appropriate for Nigerians. However, information on the quality of fish dried
using locally fabricated solar dryer in Nigeria is scanty in the literature. A
prototype solar fish dryer was therefore designed, fabricated and evaluated in
this study.
1.3
JUSTIFICATION
Biochemical changes such as glycolysis caused by
enzyme action, rigor mortis occurring in the muscle (stiffening of muscle),
muscle tendering by post-rigor, autolysis caused by the action of proteinases
(muscle protein enzymes) and finally, spoilage due to microbial action and
release of mucus occur in fish. In processing, efforts are taken to counter the
activities of these factors, in other to ensure a longer shelf life for fish,
prevent fish spoilage and retaining physical and chemical characteristics of
fish with its biological value and taste. Cooling, freezing, direct sun drying,
smoking, heat treatment, salting and applying antimicrobial agents and
antioxidants are used for processing and preservation (Amos, 2017). Effort
should be made to avoid the health, fire risk and air pollution involved in
these processing processes (Gokoglu, 2004). For instance, the quality of smoked
fish from Nigeria has been reported to be within acceptable quality limits
specified by various regulatory agencies such as SON. However, findings have
revealed microbial contamination and the presence of polycyclic aromatic
hydrocarbons in some smoked fish which values exceed the EU recommended maximum
permissible level of 5.0 μg/kg for benzo[α]pyrene (Adeyeye, 2016). Adebowale et al. (2013) reported that appropriate
improved processors and preservation techniques can significantly reduce fish
spoilage thereby prolonging the fish shelf life, improving their nutritional
values, taste, and market quality. It is in view of these that this study is
design to generate useful information on the use and effect of a novel solar
fish dryer, direct sun drying and smoking methods on the nutritive quality of
fish.
Solar dryers have many advantages over open sun
drying, smoking and artificial dryers in Nigeria. It depends solely on natural
solar (sun) energy. Nigeria is in the tropics and has a prolonged high daily
temperature to supply heat naturally to the environment. Solar dryer depends on
sun energy. It is therefore environmentally friendly, relatively cheap, has
little or no maintenance cost, durable, hygienic and feasible in every part of
the country.
1.4 OBJECTIVE OF STUDY
The main objective of this study was to construct and
evaluate the performance of the solar fish dryer on the quality of dried fishes.
The specific objectives were to:
i.
Construct a Solar fish
dryer
ii.
Compare the drying characteristics
of the constructed solar dryer with those of the open sundried and smoked fishes.
iii.
Determine the physicochemical
(proximate, minerals, vitamins, PH, free fatty acid, peroxide value)
properties of the fishes dried with constructed solar dryer, the open sundried
and the smoked fishes.
iv.
Asses the microbial
properties (total plate count) of the fishes dried with the constructed solar
dryer, the open sundried and the smoked fishes.
v.
Asses the sensory
properties (appearance, taste, aroma, mouthfeel, general acceptability) of the fishes
dried with the constructed solar dryer, the open sundried and the smoked
fishes.
Click “DOWNLOAD NOW” below to get the complete Projects
FOR QUICK HELP CHAT WITH US NOW!
+(234) 0814 780 1594
Login To Comment