This document summarizes a study that aimed to identify suitable temperature combinations for the spray dryer and fluid bed dryer in a milk powder production facility. Through a trial experiment, different combinations of spray dryer inlet temperature (175-179°C) and fluid bed dryer inlet temperature (55-75°C) were tested. Treatment combinations of 177°C/65°C and 178°C/60°C produced milk powder with acceptable bulk density (0.562 and 0.556 kg/m3) and moisture content (2.895% and 2.911%) levels. The main experiment confirmed there were no significant differences in fat content, bulk density, or scorched particles between treatments. Higher spray

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International Journal of Research Publications
Volume-5, Issue-2,May 2018
Accepted and Published Manuscript
Identification of suitable spray dryer and fluid bed dryer temperature for standard milk powder in
MILCO (Highland) Spray Dryer Milk Factory Ambewela.
U.W.L.M. Kumarasiri, K. Premakumar, J. Wickramasinghe
PII : U.W.L.M. Kumarasiri.1005252018206
DOI: 1005252018206
Web: http://www.ijrp.org/paper_detail/207
To appear in: International Journal of Research Publication (IJRP.ORG)
Received date: 29 May 2018
Accepted date: 01 Jun 2018
Published date: 03 Jun 2018
Please cite this article as: U.W.L.M. Kumarasiri, K. Premakumar, J. Wickramasinghe , Identification of
suitable spray dryer and fluid bed dryer temperature for standard milk powder in MILCO (Highland) Spray
Dryer Milk Factory Ambewela. , International Journal of Research Publication (Volume: 5, Issue: 2),
http://www.ijrp.org/paper_detail/207
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2. Identification of suitable spray dryer and fluid bed dryer
temperature for standard milk powder in MILCO
(Highland) Spray Dryer Milk Factory Ambewela.
Kumarasiri, U.W.L.M*., Premakumar, K., and Wickramasingha,J.
Department of Agricultural Chemistry, Faculty of Agriculture, Eastern University, Vantharumoolai, Sri Lanka
Lahirumadhushankaln99@gmail.com
Abstract
Ambewela MILCO (Highland) Spray Dried
Milk Factory produces milk powder under
the brand name of “Highland Milk
Powder” among five factories belongs to
MILCO Company. Moisture content of the
final milk powder can hold up to 3.00%.
Newly upgraded powder plant produces
milk powder with moisture percentage
under 2.75%. Spray Drying Inlet
Temperature and Fluid Bed Dryer Inlet
Temperatures are the main variables that
can be controlled in the main process of
milk powder production. A study was
conducted to find out the possible
temperature ranges of both Spray Drying
Inlet and Fluid Bed Dryer Inlet in order to
select the most suitable temperature range
which produces good quality milk powder
with acceptable bulk density value (0.56
kg/m3), scorched particles grade (“A”
grade) and moisture content value closer to
the 3.00 %. A trial experiment was
conducted to find out the suitable
temperature ratio of both Spray Drying
Inlet temperature and Fluid Bed Dryer
Inlet Temperatures by considering bulk
density, scorched particles and moisture
content. Possible Spray Dryer Inlet
temperatures were 175o
C, 176o
C, 177o
C,
178o
C, 179o
C, 180o
C and 181o
C. Possible
Fluid Bed Inlet Temperatures were 55o
C,
60o
C, 65o
C, 70o
C, 75o
C, and 80o
C. Based on
the trial experiment, T1 (SPI: 175o
C, FBD:
75o
C), T2 (SDI: 176o
C, FBD: 70o
C), T3
(SDI: 177o
C, FBD: 65o
C), T4 (SDI: 178o
C,
FBD: 60o
C), T5 (SDI: 179o
C, FBD: 55o
C)
selected as treatments. Final moisture
content, bulk density; scorched particles
level and fat levels were taken into
consideration for the quality parameters of
milk powder. Fat level of the final milk
powder indicated that there was no any
significant difference (p>0.05) between
treatments. Spray Dryer Inlet
Temperatures of 177o
C, 178o
C and Fluid
Bed Dryer Inlet Temperatures of 65o
C,
60o
C ( T3 and T4) produced acceptable
bulk density levels and moisture content
levels of 0.562 kg/m3
, 0.556 kg/m3
and
2.895%, 2.911% respectively. There was no
any significant difference (p>0.05) between
treatments.
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3. Keywords: Spray Dryer Inlet Temperature,
Fluid Bed Dryer Inlet Temperature,
moisture content, bulk density, scorched
particles level and fat level.
I. Introduction
Milk is defined as the lacteal secretion
obtained by the complete milking of one or
more mammalian animals. It is a white liquid
produced by the mammary gland of mammals
and the primary source of nutrition for infant
mammals before they are able to digest other
type of food. In more recent times, milk has
been dried in thin films on heated rollers. Such
roller drying was the main method of
producing milk powders until the 1960s when
spray drying became prevalent.
Ambewela MILCO (Highland) Spray Dried
Milk Factory is located in the upcountry
region (Ambewela) of Sri Lanka. From year
2000 onwards MILCO (Pvt) Ltd Company
taken by government and currently it has 4
milk processing factories located in Colombo,
Ambewela, Digana and Polonnaruwa.
Ambewela factory produces instant full cream
milk powder and butter. Final Moisture
content of the milk powder plays an important
role in physiological quality of the milk
powder as well as the economical aspect. Final
moisture content of milk powder is mostly
affected by Spray Dryer and Fluid Bed Dryer
input conditions.
Standard final moisture content of the
Highland Milk powder ranges 2.3 – 3.00%
from its total weight. Highland milk powder
contains lower moisture content than standard
value (3.00%). Therefore, this study was
conducted in Ambewela MILCO (Highland)
Spray Dried Milk Factory to find out the most
suitable ratio of both spray drier inlet air
temperature and fluid bed inlet air temperature
for achieving the standard moisture level of
3.00% (maximum), standard bulk density level
0.56 kg/m3, standard scorched particle's grade
A and standard fat level 26.0% (minimum).
II. Materials and method
This research study was conducted in
Ambewela MILCO (highland) Spray Dried
Milk Factory to find out the most suitable
combinations of both Spray Drier Inlet
Temperature and Fluid Bed Dryer Inlet
Temperature to obtain standard fat level
(26.0%), bulk density level (0.56 kg/m3) and
moisture content (Near to 3.00%) in the milk
powder.
Trial Experiment was conducted by giving
different combinations of Spray Drier Inlet
Temperatures and Fluid Bed Dryer Inlet
Temperatures. First sample was collected from
the bottom of the spray dryer. Second sample
was collected from the inlet of the fluid bed
dryer. Final sample was collected from the
outlet of the fluid bed dryer. Every time
approximately 60 g of milk powder was
collected. Laboratory tests were carried out to
find out the Fat Level, Moisture Level and
Bulk Density Level of the milk powder.
Among them, suitable temperature
combinations were selected based on the bulk
density level and scorched particle levels and
U.W.L.M. Kumarasiri / International Journal of Research Publications (IJRP.ORG)
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4. moisture content level. Main experiment was
carried out by providing selected temperature
combinations. Among them best Spray Drier
Inlet Temperature and Fluid Bed Dryer Inlet
Temperature combination was selected based
on the moisture content of the milk powder
near to 3% with optimum powder quality
levels of other parameters such as bulk
density, fat level and scorched particles.
Data of the trial experiment and main
experiment were analyzed by Analysis of
Variance (ANOVA) (α = 0.05) and mean
separation was done with Tukey's Honest
Significant Difference test.
III. Results and discussion
• Trail Experiment
Results of trial experiment were analyzed and
best five treatments were selected for further
experiment. In this context, Presence of
Scorched particles and bulk density levels
were compared with quality standards of milk
factory and five Spray Dryer Inlet and Fluid
Bed Dryer Inlet temperatures were
selected according to those results.
1. Spray Dryer Inlet Temperature
Table 1.0 Bulk Density Levels and Scorched Particle Grades of
the Powder Samples Collected from the Bottom of the Spray
Dryer.
Temperatures Bulk Density Scorched Particles
175o
C 0.55a± 0.02 A
176o
C 0.53b± 0.01 A
177o
C 0.53c±0.02 A
178o
C 0.50d±0.01 A
179o
C 0.47e±0.02 A
180o
C 0.45f±0.01 B
181o
C 0.41G±0.01 B
The values are means of replicates ± standard error
The means with the same letters are not significantly different at tukey`s test 5% level
Possible range of Spray Dryer inlet
temperature was 175o
C to 179o
C. Due to the
presence of scorched particles at higher
temperatures, further increment of inlet
temperature was avoided. Inlet temperature of
spray dryer shows negative correlation with
scorched particles value [1]. When the inlet air
temperature was raised to 225°C from 155°C,
the bulk density and the mean powder particle
density were decreased whereas the vacuole
volume was increased. This was evidently
caused by rapid drying and moisture
expansion in the powder particles [2].
2. Fluid Bed Dryer Inlet Temperature
Figure: 1.0 Relationship of Mean Values of Bulk Density
Reduction and Fluid Bed Dryer Inlet Temperatures
Figure 2.0 Relationships of Mean Values of Moisture Content
Reduction and Fluid Bed Dryer Inlet Temperatures
0
0.05
0.1
0.15
0.2
0.25
45 55 65 75 85
MeansofBulkDensityreduction
kg/m3
Fluid Bed Dryer Inlet Temperature (oC)
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
60 70 80
MeansofMoisturecontent
reduction%
Fluid Bed Dryer Inlet temperature (oC)
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5. 24
25
26
27
28
T1 T2 T3 T4 T5
Fat%ofmilkpowder
Treatments
Results taken from trail experiment indicated
that possible Fluid Bed Dryer inlet
temperature ranged from 55o
C to 75o
C. Along
with constant spray dryer inlet temperature
(178o
C) at different fluid bed dryer, results
indicated that at higher fluid bed inlet
temperatures tend to reduce the bulk density of
milk powder and overall powder moisture
content. Increment of fluid bed dryer
temperature causes the reduction of final
moisture content as well as reduction of bulk
density of milk powders [3]. Increase in drying
temperature increases moisture evaporation
thus reduces the final moisture content of the
milk powders [4].
3. Treatments
Based on the results of above trial experiment,
following five treatments were selected for
Main experiment.
Table 2.0 Selected Treatments for the Main Experiment
• Main Experiment
For each treatment, four replicate samples
were collected.
1. Scorched Particles
Table 4.4 Scorched Particle Grade Results
All treatment temperature combinations gave
“A” Grade scorched particles value according
to the ADMI (American Dry Milk Institute)
standards. Results were proved that scorched
particles do not only depend of the inlet
temperatures of Spray Dryer and Fluid Bed
Dryer. Scorched Particles may be the result of
powder deposits in the spray drying chamber
which are coming free to contaminate product.
Spray dryer air flow must be managed
effectively to avoid powder accumulations
which may result in scorched particles and the
linked problem of fire and explosions [5].
2. Fat Content
Figure 3.0 Relationship between Inlet Temperatures of
Spray Dryer and Fluid Bed Dryer on the Fat Level of
Milk Powder
Homogenization distributes small fat globules
uniformly throughout the milk powder
particles. Standardization process was the
main factor that affected the final fat content
Treatments
Spray Dryer
Inlet
Temperature
Fluid Bed Dryer
Inlet
Temperature
T1 175o
C 75o
C
T2 176o
C 70o
C
T3 177o
C 65o
C
T4 178o
C 60o
C
T5 179o
C 55o
C
Treatments
Scorched Particle Grade
R1 R2 R3 R4
T1 A A A A
T2 B A A A
T3 A A A A
T4 A A A A
T5 B A A A
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6. 2.768
2.789
2.895
2.911
2.843
2.65
2.7
2.75
2.8
2.85
2.9
2.95
T1 T2 T3 T4 T5
MoisturePercentage
Treatments
0.612
0.596
0.562
0.556
0.536
0.48
0.5
0.52
0.54
0.56
0.58
0.6
0.62
T1 T2 T3 T4 T5
Fat%ofmilkpowder
Treatments
in the milk powder. Final fat content level of
dried milk powder was influenced by
standardization procedures at greater scale [6].
3. Bulk Density
Results of the Bulk revealed that selected
treatments showed no any significant
differences (p>0.05) between the means of
bulk density.
Figure 4.0 Relationships between Treatments and Final
Powder Bulk Density
Reduction in Fluid Bed Dryer Temperature
reduces the agglomeration process and bulk
production of milk particles. This causes to
produce more fine particles. Bulk density and
degree of shrinkage increase with increase in
input temperature. [7]
4. Moisture Content
Figure 5.0 Relationships between Treatments and Final
Moisture Content of the Milk
Powder
Results indicated that increasing of Spray
Dryer inlet temperature and simultaneous
reduction of Fluid bed Dryer Inlet
temperatures had a noticeable effect on the
final moisture content. Increment of residual
moisture content of the powder can be
obtained by reduction of inlet air temperatures
[8]. Inlet air temperature shows maximum
negative effect on the moisture content. The
increase in moisture content at lower inlet air
temperatures is due to the smaller temperature
gradient between the atomized feed and the
drying air, resulting in a smaller driving force
for water evaporation and thus produces
powders with higher moisture content [9].
IV. Conclusion
During trial experiment, higher Spray Dryer
Inlet Temperatures such as 180o
C and 181o
C
produced scorched particles which were
undesirable for commercial production of milk
powder. Based on the trial experiment, most
suitable Spray Dyer Inlet and Fluid Bed Dryer
Inlet temperature combinations were selected
as treatments. Most suitable temperature
combinations were 177o
C, 178o
C and 65o
C,
60o
C (Treatment 4 and 5). Treatment 3 and 4
indicated increment of moisture content
(respectively 2.895 %, 2.911 %) as compared
with other treatments.
Increment of moisture content in Milk Powder
increased the bulk weight of the final product
and increases the bulk production of the milk
powder in Ambewela MILCO (Highland)
Spray Dried Milk Powder Factory. According
to the quality standards in the factory,
U.W.L.M. Kumarasiri / International Journal of Research Publications (IJRP.ORG)
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7. adjustment of milk powder moisture content
was desirable to produce high quality milk
powder with good consumer acceptance.
V. References
[1] Piecky, J. (1998). Bulk density of milk
powders. Dairy Industry 43:4–7, 10–11.
[2] Vilder, J. De, Martens, R, Naudts, M.,
(1996). Influence of process variable on
some whole milk powder characteristics.
Mi1chwissenschaft 3 l. 396-401.
[3]Senadeera. (2009). Density Variation of
Different Shaped Food Particulates in Fluid
Bed Drying: Agricultural and Marine
Sciences, 14:27-34.
[4]Haron, N. S. (1999).Recent advances in
fluidized bed drying; Conf. Ser.: Mater. Sci.
Eng. 243
[5]Beever, P.F., (1994). Fire and explosion
hazards in the spray drying of milk.
Developments in Milk Powder Technology.24;
415–422.
[6]Seals, R. G. (1969). Organoleptic
Evaluation of the Effectiveness of
Antioxidants in Milk Fat. Departments of
Dairy and Food Industry and Food and
Nutrition, Iowa State University, Ames 50010.
Journal Paper no. J-6206.
[7]Baysal, T., Icier, F., Ersus, S., Yıldız, H.
(2003). Effects of microwave and infrared
drying on the quality of carrot and garlic.
[8]Caric, M. (1994). Effects of drying
technologies on milk powders quality and
microstructure. Dairy Ind. Worldwide 5. 25-
27.
[9]Muzaffar, K., and Kumar, P., (2015).
Parameter optimization for spray drying of
tamarind pulp using response surface
methodology. Powder Technology, 279, 179–
184.
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