Pakistan Journal of Nutrition 8 (7): 955-957, 2009
© Asian Network for Scientific Information, 2009
Comparative Study of Sun Drying and Solar Tent
Drying of Hyperopisus bebe occidentalis
R.O. Ojutiku, R.J. Kolo and M.L. Mohammed
Department of Water Resources, Aquaculture and Fisheries Technology,
Federal University of Technology, Minna, Niger State, P.M.B 065, Nigeria
Abstract: An experiment was conducted to investigate the effect of two drying processing methods on the
nutritional qualities of Hyperopisus bebe. The two methods used were solar tent dryer and traditional sun
drying methods. The experimental fish were dried for 120 h (5 days). The results of proximate analysis
showed significant difference (p<0.05) between the two techniques. Organoleptic evaluation showed no
physical damage, no discolouration in the treatments and both had firm texture though fishes under
traditional sun drying were infected by insects.
Key words: Traditional sun drying, solar tent, Hyperopisus bebe
Fish is a highly nutritious food and it is particularly
valued for providing protein of high quality better than
those of meat and egg. However, it is one of the most
perishable of all the foods because it is a suitable
medium for growth of micro-organisms after death.
Igene (1983) found that in the tropics at ambient
temperature, spoilage is rapid; fish will spoil within 12-
20 h depending on species, method of capture. As soon
as fish is caught and dried, certain irreversible spoilage
begin to take place, leading to spoilage and
deterioration (Conne, 1995) and most subsequent
processing or preservation operation are intended to
prevent these causes or usually reduce the rate at which
they proceed (Eyo, 1986).
Sun drying is one of the traditional methods employed to
preserve fish. It has been observed as the most
convenient and cheapest form of preservation in Nigeria
(Eyo, 1986). The need to use solar radiation/energy for
fish drying has become even more than necessary at the
present time because of the huge competitive demand
for fuel wood for fish smoking. Solar drying is an
improved method of sun drying. It minimizes or stop
some of the limitations of open sun drying. It differs from
open sun drying in that a structure, often very simple in
construction is used to enhance the effect of the
insulation due to the fact that solar tent dryer is an
enclose structure that traps heat inside the tent and
make effective use of the heat which is stored inside the
tent both in the day and night by the help of some rocky
stones which are painted black to absorb heat.
Hyperopisus bebe occidentalis is the sole specie of
genus Hyperopisus. It has a small rayed fin situated well
to the rear of the body. This specie inhabits in both rivers
and swamps and is one of the most common momyrids
the commercial catches.
This study assessed and compared the organoleptic
and proximate composition of solar tent dried fish and
open sun dried fish.
MATERIALS AND METHODS
The design of the solar tent dryer is based on
horticultural green house. It consists of a plastic
polythene sheet stretched over a wooden frame work (3
feet wide by 4 feet long by 4 feet high) with side and top
vent (1 by 1 feet) and the fish rack (1.5 feet by 1.5 feet)
were placed with wire mesh under and underneath were
painted rocks which was used as a heat collector and
Sun drying rack was constructed by placing sack on a
concrete floor and a wooden frame work was
constructed from chicken wire mesh which was used to
cover the sack that is placed directly under the sun for
maximum utilization of the sun.
The experimental fish (Hyperopisus bebe) used for the
experiment were purchased and transported to the
laboratory for further analysis. They were washed and
manually operated by descaling and gutting was carried
out. The gutted fish were arranged on the tray within the
solar tent dryer (treatment B) and open sun drying
Proximate analysis was carried out on the fresh fish
before the experiment and on the experimented fish
every 24 h for 5 days. The analysis was done using the
method of AOAC, 1980. The parameters measured were
crude protein, ash, crude fibre, moisture content, lipids.
Organoleptic assessment was also carried out using a
Table 1:Fresh proximate composition of Hyperopisus bebe
Pak. J. Nutr., 8 (7): 955-957, 2009
Table 2: The daily proximate composition of crude protein, lipid, ash and crude fibre
Day 1 (24 h)3.36±3.39±3.70±
Day 2 (24h)3.15±2.88±3.99±
Day 3 (24 h)2.02±1.74± 6.68±
Day 4 (24 h)0.28± 0.29±8.36±
Day 5 (24 h)0.12±0.23±6.26±
Hedonic scale grading base on method of Doe and
Olley (1990). Analysis of variance was used to
statistically test the results.
discolouration was observed in the treatments. The
texture of the two treatments was also observed to be in
good condition throughout the experiment.
Bacteria infestation was observed in treatment B which
was the traditional sun drying method during the first
and second day of the experiment.
throughout the experiment. Also, no
The proximate analysis of the fresh Hyperopisus bebe
were 74% moisture, 29.96% crude protein, 1.57% ash
and 0.2% crude fibre (Table 1)
The daily proximate composition of crude protein, lipid,
ash and crude fibre analyzed were increasing in the two
treatments (A and B) from the first day to the last day of
the drying process i.e. fifth day (Table 2). The highest
protein was recorded treatment B which is the solar tent
dryer with a value of 62.5% on the fifth day while
treatment A which is traditional sun drying was 59.8% in
the fifth day. There was no significant difference (p>0.05)
among the days of the experiment but significant
difference (p<0.05) was observed between the
The moisture content range of the treatment B was 65%
in the first day to 10% in the fifth day while treatment A
was 69-11.5% in the last day (Table 2). Significant
difference (p<0.05) was observed between the
Table 2 also shows the lipid composition of the two
treatments. The lipid concentration of traditional sun
dried fish ranged between 30.2% in the first day to
28.30% In the fifth day while solar tent dried fish ranged
was 29.4% In the first day and 26.50% in the last day of
the experiment. Significant difference was also observed
The ash content of the experimented fish is also
presented in Table 2 which ranged between 2.50-11.1%
in the fifth day I treatment A and 0.5-1.94% in treatment
B and significant difference (p<0.05) was observed.
The crude fibre of the two treatments increased from the
first day to the last day (Table 2). Traditional sun dried
ranged from 0.5-1.94% in the fifth day while solar tent
dried (treatment B) ranged from 0.3% in the first day to
2.4% in the fifth day. Significant difference (p<0.05) was
also observed between the treatments (Table 2).
The organoleptic evaluation
appearance of the two treatments were in good
Conclusion: From this study, the solar tent dryer has
proven to be more efficient and reliable form of fish
preservation and processing using the ambient solar
energy. The products were of good quality compare to
sun drying in terms of nutritional value and hygienic
showed that the
The moisture content of both treatment A and B reduced
from 74-11.5% and 10% respectively which agreed with
Clucas (1982). Clucas (1982) reported that a fish well
dried or moisture content reduced to 25% will not be
affected and if further dried to a moisture content of 15%,
the growth of mould will cease and increase the shelf
The protein content of the experimented fish was
23.33% which increased to 59.8% and 62% in treatment
A and B respectively. This agrees with Cowey and
Sargent (1972) who reported that as moisture content of
fish reduces, the protein content increases. They further
observed that the crude protein in fish is between 50%
and 70% which agrees with this finding.
The lipid content of this fresh fish was 29.96% which
agrees with the findings of Conne (1995) who reported
that lipid content of fish varies from lean fish to fatty fish.
The reported that fatty fish is between 21-30% and could
be above and Hyperopisus bebe is a fatty fish. The lipid
content reduced to 28.50 and 26.50% in treatment A and
The ash content of the fresh Hyperopisus bebe was
1.57% which increase to 11.1% in treatment A and
9.40% in treatment B. This finding agrees with Tunison
et al. (1990) who observed ash content to be between
2.50 and 4.60%.
Pak. J. Nutr., 8 (7): 955-957, 2009
It was also discovered that an average fisher man/fish
farmer can own a solar tent dryer in his/her farm with just
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