The frozen Horse mackerel were purchased from local
market and then delivered to the laboratory on ice. The
weight of the individual fish was 95 ± 5 g with an overall
length of about 20 ± 1 cm. The proximate compositions
of frozen fish were moisture content 74.0% (w.b.), protein
22.05% (w.b.), fat content 2.55% (w.b.) and ash 1.33%
(w.b.). Before the experiment, the fish were thawed, washed
and gutted, then followed by cutting in half through the
dorsal flesh.
Nomenclature
a* hunter redness value
b* hunter yellowness value
BAR evaporator bypass air ratio (decimal)
d.b. dry basis (kg water/kg dry solids)
DR drying rate, kgH2O=kgðd:b:Þ h
E hunter colour difference
HPD heat pump dehumidifier/dryer
L* hunter lightness value
M moisture content (%)
MR moisture ratio, dimensionless
NaCl sodium chloride
RH relative humidity (%)
SMER specific moisture evaporation rate (kg/kW h)
T temperature (C)
w.b. wet basis (kg water/kg mass)
Greek symbol
D change in colour parameters
Subscripts
0 initial moisture content
1 before heat pump dehumidifier drying
d dry basis
e equilibrium moisture content
i drying time i
i + 1 drying time i + 1
r refrigerant
t drying time t
w wet basis