Encapsulization of Channa striatus Extract by Spray Drying Process
A.M. Mat Jais,
Channa Striatus is known as snakehead fish or local name as haruan, has been always associated with its medical value especially in wound healing. This fish is rich in protein as well as others biochemical compounds such as polyunsaturated fatty acids and antioxidants. Usually, the haruan is extracted and marketed in the form of liquid concentrated as health food supplement. In this study, encapsulated haruan extract were produced using spray drying process. The main purpose is for easy handling and the preservation of the biochemical compounds. The biochemical compound in the powder produced is expected to have properties such as more stable and longer shelf life. K-carrageenan was used as coating material for the encapsulzation during the spray drying process. The properties of encapsulated powder produced were observed in term of particle size distribution, Fish Protein Hydrolysates (FPH) and moisture content. The process parameters of spray drying process studied were hot air inlet flow rate, temperature and the liquid feed flow rate. The experimental run and optimization were designed using Box-Behnken method as suggested by Response Surface Methodology (RSM). The optimum operation conditions for highest protein extracted with lowest moisture content and smallest particle size distribution were obtained at hot air inlet temperature and flow rate of 144.51°C and 400 mL h-1, respectively; whereas, the liquid feed flow rate is at 47 m3 h-1. The optimal properties of encapsulated powder obtained were 5.2850 μm, 91% of protein and 8.7% in moisture content.
Haruan or also known as murrel in west countries is belonged to the family
Channidae or Ophiocephalidae and its scientific name is Channa striatus
(Pillay and Kutty, 2005). Channa striatus is different
from other fishes as it possesses ability to breathe atmospheric oxygen and
this keeping them alive long even out of water. It is well known as food fish
in South and Southeast Asian countries. In Malaysia, haruan is also considered
by most Malaysian as a good source of health food. Besides the high quality
of the flavor and texture of the flesh, C. striatus is widely believed
by Malaysians to have remedial effects in ameliorationg wound lesion, port-parturition
and various skin diseases. This is because the C. striatus contains lots
of polyunsaturated fatty acids (PUFA). A fatty acid compositional study of the
flesh of Haruan revealed unusually high arachidonic acids (ARA) but almost no
eicosapentaenoic acids (EPA) which were hypothesized to be active component
in the initiation of wound repair (Mat Jais et al.,
1994). Essential amino acids such as glycine and essential fatty acid such
as arochidonic acid have been shown to actively participate in the normal blood
clotting mechanisms by facilitating wound healing as well as in enhancing the
antinociceptive activity (Mat Jais et al., 1997;
Baie and Sheikh, 2000). There were extensively studies
on the beneficial effect of C. striatus in wound healing, antinociceptive
activities and composition of the amino acids in the C. striatus. However,
this study is limited to the extract of the fish fillet in the liquid form and
no research has been done to study on the extract in spray dried powder form.
Currently, there are products of the haruan extract in the market are in the
liquid form for consumption purpose and also in the cream form which utilized
for external treatment on the skin. The essence of haruan in liquid form often
exhibits some problems like short lifespan, handling problems. The haruan extract
in liquid form also very often present a physicochemical instability during
their storage as there is present of water. Moreover, the extracts in liquid
form have restriction in the mobility of the product as it may be too heavy
to be carried along by the consumers.
Therefore, in this study, spray drying method is utilized to spray dried the
haruan extract. Spray drying is the common method for producing a dry powder
from a liquid (Masters, 1985). It results in powders with
controllable particle sizes, low moisture and easier transport and storage (Tonon
et al., 2008). In this study, the relationship between the some process
variables and resulting the characteristics of encapsulated haruan extract is
also studied. The encapsulisation process parameters explored were spray dryer
inlet temperature, liquid feed rate and the drying air flow. The powder characteristics
such as size distribution, protein and moisture content were analyzed.
MATERIALS AND METHODS
The research conducted here was involving of selection of materials, extraction of bio-compounds from haruan fish, encapsulisation of the fish extract and characterization of encapsulated product. The extraction of bio-compounds from fish was using conventional boiling technique, whereas the production of extract powder by spray drying technique. The characterization of extract powder was particle size distribution, protein and moisture content. Experimental design was also used to assist the selection of the range of process parameter.
Materials: The haruan fish was supplied from the local farm and the weight of the fishes were in the range of 400 to 700 g. The wall materials (K-carrageenan) for encapsulisation was obtained from Fluka. Other analytical chemicals were purchased from Sigma Aldrich.
Preparation of haruan extract: Haruan fish weighing 400 to 700 g were utilized. The live fish was weighed and pre-cleaned with distilled water and is placed into a plastic bag which filled with distilled water. The distilled is at ratio 1:1 to the weight of the fish. The plastic bag containing the fish was then being placed into the freezer at 0°C for overnight. This is because the haruan will secret the mucus as protection when placed in low temperature environment. This can ease the process of cleaning the fish as all the mucus has been secreted out into the distilled water. The frozen fish was then thawed and the fish fillets were obtained by carefully cutting the fish lengthwise along the backbone to get the maximum amount of flesh without any bones. The skin of the haruan fish is cleaned as only fish fillet needed in this study. The fish fillet was then rinsed using distilled water and was weighed for the extraction process.
The fish extraction process is carried out using a pressure cooker set at 100°C
for 2 h (Mat Jais et al., 1994). The boneless
fillet was cleaned using distilled water and weighed. It then was placed into
the stainless steel pressure cooker and distilled water was added into it. The
distilled water was added with the ratio (fish: water volume) of 1:4. The fish
fillet is cooked for 30 min, distilled water was added to original volume before
it was further cooking for another 30 min. The steps were repeated every 30
min up to total 2 h cooking time. Finally, the used fish fillets were discarded
and the liquid extract was collected. The fish extract was then filtered and
stored at 4°C.
Spray drying: Prior the spray drying process, a solution of 0.5% K-carrageenan was added to the fish extract at the volume ratio (K-carrageenan:haruan extract) of 1:9. Spray drying was performed in a laboratory scale spray dryer LabPlant SD-05 (Huddersfield, England), with a l.5 mm diameter nozzle and a main spray chamber of 500x 215 mm. The mixture was fed into the main chamber through a peristaltic pump and the feed flow rate was controlled by the pump rotation speed. Inlet air temperature varied from 130 to 150°C, the feed flow rate varied from 200 to 400 mL h-1 and the drying air flow rate varied from 47 to 62 m3 h-1. The air pressure was maintained at 1.2 MPa.
Particle size distribution: The particles size distribution was analyzed
using the Laser Scattering Particles size Distribution Analyzer LA-300 (Horiba)
(Mat Jais et al., 2008). The measurement technique
was conducted according to the operation manual of the instrument given by instrument
Protein content: Kjedahl method was applied to measure the protein content
in the haruan extract powder (Zakaria et al., 2007).
Three steps were involved in the determination of protein content which are
digestion, titration and distillation. Digestion was done with digester at 80°C
for 2 h. The process of titration and distillation was conducted using Kjeltech
instrument which is a part of the operation of this instrument.
Moisture content: The moisture content was analyzed using the HG53 Halogen Moisture Analyzer (Mettler Toledo). A quantity of 0.3 g of the extract powder sample was placed in an aluminum plate, the powder was heated to dry off the moisture for 5 min and the moisture content was identified.
Experimental design: The experimental design was done with the aid of the Design Expert software which uses the Response Surface Methodology, Box-Behnken design to determine the number of runs needed in this study. Response surface methodology was used as this study
was aimed at process optimization which means finding out the best combination of parameters which can produce the quality fine particles (Awang Bono et al., 2008). In Box-Behnken design, each numeric factor which is the process parameter was varied over 3 levels (-1,0,+1). The range for each and every parameter was; inlet air temperature: 130, 140 and 150 oC, feed flow rate: 200, 300 and 400 mL h-1 and air flow rate: 47, 45.5 and 62 m3 h-1.
RESULTS AND DISCUSSION
Response surface analysis: The responses measured from the experimental work are shown in Table 1. Total up to 17 run out of three factors. The ANOVA analysis is shown in Table 2.
The quadratic models for particle size, protein content and moisture content in terms of coded factors are shown, respectively in the Table 2.
Particle size distribution: The influence of the different inlet drying
temperatures (130, 140 and 150°C) on the particle size distribution is shown
in Fig. 1a. The particle size decreased gradually with increasing
temperature until it reached a minimum particle size at about 140°C. Above
140°C, the particle size started to increase gradually. The increase on
inlet air temperature resulted in larger particles, which is related to the
higher swelling caused by higher temperature. The particles remains shrunk when
inlet drying air temperature is low and thus with smaller diameter (Tonon
et al., 2008). According to Reiniccius (2001),
larger particles will be formed when it is dried at conditions that result in
faster drying rates than drying conditions that result in slower drying rate.
This is due to the fact that very fast drying sets up as early structure and
does not allow the particles to shrink during drying. When inlet temperature
is low, it will results in slower drying and the particle will shrink and thus
results in smaller particle diameter. Nijdam and Langrish
(2006) who carried out study with the production of milk powder at 120 and
200°C obtained similar results. Hsu et al. (1996),
presented a theory based on the fact that a skin is formed on the outer surface
of the spray droplets at high inlet drying air temperature. The outer skin formed
is destroyed when the inner water phase is evaporated and the outer surface
collapse. From Fig. 1b, the particle size increases with increasing
air flow rate until a maximum particle size is produced at air flow rate of
about scale 35. Above that, the particle size decreases with the increasing
air flow rate. Theoretically, the particle size should reduce with increased
inlet air flow rate. According to Stahl et al. (2002),
increased atomization nozzle flow which is equivalent to the inlet air flow
rate reduced the particle size. This is due to the higher the atomization flow
or air flow rate, the more energy is supplied for breaking up the liquids into
droplets during the atomization step, resulting in smaller droplets formed (Masters,
1985). From the Fig. 1c, it is cleared that the mean particle
size increases with the pump flow rate which also known as feed flow rate of
the C. striatus extract with k-carrageenan. According to Rattes
and Oliveira (2007), the increase in feed flow rate augment the mean diameter
of the atomizing drops during spray drying and thus contribute for the increase
in the mean powder diameter.
|| ANOVA analysis for response surface quadratic model of the
haruan extract powder properties
|Where, A: Inlet drying temperature, B:Pump flow rate or feed
rate and C: Air flow rate
||(a) Particle size distribution for air flow rate of scale
40 which is 62 m3 h¯1, (b) Particle size distribution for pump flow
rate of scale 400 mL h¯1 and (c) Particle size distribution for inlet
air temperature of 140°C
Protein content: From Fig. 2a, it is cleared that
the protein content increased exponentially with increasing inlet drying temperature.
The effect of the inlet drying temperature on the protein content depends on
its effect on moisture content of the powder produced. The moisture content
is inversely proportional to the protein content of the powder. The higher the
moisture content of the powder, the lower the protein content contained in the
powder formed. This is due to as the water evaporated from the spray droplets,
the protein content inside the powder become more concentrated and thus resulting
in higher protein content within the powder itself. Thus, the protein content
increased with increasing inlet air drying temperature. Besides, when the inlet
drying air temperature increased, the size of the spray droplets also increased.
When the size of spray droplets become larger, the inside component that can
be shielded by the external shell also increases and contribute to higher protein
content (Zhou et al., 2004).
The effect of the inlet drying air flow rate and pump flow rate on the protein
content also depends on its effect on the moisture content of the powder. When
the inlet drying air flow rate increases, the residence time of the spray droplets
in the drying chamber is decreased and thus resulting in higher moisture content
and thus lower protein content of the powder formed (Fig. 2b,
Moisture content: From the Fig. 3a, the moisture content
decreased with increasing inlet drying temperature until minimum moisture content
at about 140°C. Above the 140°C, the moisture content started to increase
gradually until 150°C. Ranging over the pump flow rate, the same trend happened.
The powder moisture content decreased with increasing inlet drying temperature.
The inlet drying temperature was the variables that showed greatest influence
on powders moisture content. This is because at higher inlet air temperatures,
there is a greater temperature gradient between the atomized feed and the drying
air, there is a greater heat transfer into the particles, resulting in a greater
drying force for water evaporation and thus producing powders with lower moisture
content (Quek et al., 2007). Goula
and Adamopolous (2005) who was working with the spray drying of the tomato
pulp in dehumified air also concluded that an increase in the inlet air drying
temperature leads to a decrease in moisture content. When the drying medium
is air, temperature plays a vital role. As water is driven from the particles
in the form of water vapor, it must be carried away. Or else, the moisture will
create a saturated atmosphere at the particle surface and this will slow down
the rate of subsequent water removal. The hotter the air, the more moisture
it will be hold before becoming saturated. Thus, high temperature in the vicinity
of the drying particles will take up the moisture that being driven out from
the food to a greater extent compared to cooler air (Goula
and Adamopolous, 2005) and thus resulting in smaller particles formed. Rattes
and Oliveira (2007) and Grabowski et al. (2006)
also observed the same finding that is a reduction of powder moisture content
with the increasing inlet drying air temperature, studying the spray drying
of watermelon juice, sodium diclofenac and sweet potato puree, respectively.
However, the increases of inlet air drying temperature leads to a lower moisture
contents do have exception for the increase from 140 to 150°C with a drying
air flow rate of 62 m3 h-1 (Fig. 3b).
Goula and Adamopolous (2003) also observed this exception
when the inlet air temperature increases from 130 to 140°C, the moisture
content of the particle increases. In this case, due to the high air temperature,
the surface of the thermoplastic particles remains plastic resulting in sticking
of the drying droplets among themselves and the drying rate decreases as the
surface area of contact decreases (Goula and Adamopolous,
From the Fig. 3b, the powder moisture content increases with
an increase in the drying air flow rate. Generally, the amount of drying air
determines the energy available for evaporation. The movement of air predetermines
the rate and degree of droplets evaporations by influencing the passage of the
spray through the drying zone in the drying chamber, the concentration of the
product in the region of dryers walls and the extent to which the semi-dried
particles re-enter the hot areas around the air disperser (Goula
and Adamopolous, 2005). When the drying air flow rate is low, it causes
an increase in the product sojourn time in the drying chamber (Masters,
1979) and enforces circulation effects (Goula and Adamopolous,
2004; Oakley and Bahu, 1991). Increased residences
times in the drying chamber lead to a greater degree of moisture removal. In
conclusion, an increase in the drying air flow rate decreases the residence
time of the spray droplets in the drying chamber and thus led to lower moisture
removal and higher moisture content in the spray powder. The pump flow rate
or feed flow rate negatively influences the powder moisture content as shown
in the Fig. 3c. The increase in the pump flow rate will result
in the powder with greater moisture content.
||(a) Powder protein content for inlet air temperature of 140°C,
(b) Powder protein content for air flow rate of scale 40 which is 62 m3
h¯1 and (c) Powder protein content for pump flow rate of scale 400
This is because of higher flow rates imply in a shorter contact time between
the feed and the drying air, making the heat transfer between the feed and the
drying air less efficient and resulting in lower water evaporation (Tonon
el al., 2008). Hong and Choi (2007) who carried
out study on the physicochemical properties of protein bound polysaccharide
from Agaricus blaze Murill by ultrafiltration and spray drying process, had
verified that the powder moisture content increased with increasing pump flow
rate and with decreasing inlet air temperature and the effect of the temperature
was greater than the effect of the pump rate.
Optimization of process parameters on spray drying process: The result obtained from RSM showed that the optimum process parameters, the inlet drying temperature is 144.56°C, the pump flow rate is 400 mL h-1 and air flow rate is 47 m3 h-1 whereas the optimum responses of the process, particle size distribution is 5.2744 μm, protein content is 91.2124% and mean size and moisture content is 8.6915% with desirability of 0.923.
The effects three process parameters or variables which are inlet drying temperature,
the pump flow rate or feed rate and nozzle gas flow rate on the physical and
chemical properties of the spray dried C. striatus extract have been
evaluated by 3 levels Box-Behnken experimental design. In conclusion, the inlet
drying temperature showed significant effect on all the responses; the particle
size distribution, the protein content, the moisture content studied. It was
||The powder particle size decreases with a decrease of feed
flow rate and inlet temperature. However the decreases of air flow rate
will rised the powder particles sizes
||The decreases of air flow rate and feed flow rate will raise the protein
content. The increases of air temperature will also raise the protein content
of the powder
||The powder moisture content was reduced with the increases of inlet air
temperature and decreases in both of feed and air inlet. flow rate
The result obtained from RSM showed that the optimum process parameters, the
inlet drying temperature is 144.56°C, the pump flow rate is 400 mL h-1
and air flow rate is 47 m3 h-1 whereas, the optimum responses
of the process, particle size distribution is 5.2744 μm, protein content
is 91.2217% and mean size and moisture content is 8.6915%. There were seven
combinations of the optimized process parameters with optimum value with predicted
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