FACULTY OF APPLIED SCIENCE
LAB REPORT
MARKS : 15
INSTRUMENTAL ANALYSIS OF FOOD
NAME SITI NUR HAJAR BT MOHD ZAIN
STUDENT ID 2018425222
PRACTICAL 9: DETERMINATION OF VISCOSITY
TITLE OF EXPERIMENT OF FOOD PRODUCTS USING A VISCOMETER.
DATE OF EXPERIMENT 2 OCTOBER 2019
GROUP AS2466B
LECTURER’S NAME DR. RASEETHA VANI SIVA MANIKAM
FST 606
TITLE
Practical 9: Determination of viscosity of food products using a viscometer.
OBJECTIVE
1. To determine the viscosity of food product using a viscometer based on different
speed and spindle.
2. To determine the application of viscometer.
INTRODUCTION
Viscometer, instrument for measuring the viscosity (resistance to internal flow) of a
fluid. In one version, the time taken for a given volume of fluid to flow through an opening is
recorded. In the capillary tube viscometer, the pressure needed to force the fluid to flow at a
specified rate through a narrow tube is measured. Other types depend on measurements of the
time taken for a sphere to fall through the fluid, or of the force needed to rotate the inner
cylinder of a coaxial pair (the space between the two cylinders being filled with the fluid
under test), or of the rate at which oscillations of a disk vibrating in the fluid die out. It
describes the internal friction of a moving fluid. Viscosity testing is one of the most important
methods used to check the quality of materials. Various industries rely on viscosity checks of
their products to produce a product with consistent texture. Many important parameters for
the production control of materials and also for the development of new products are directly
related to the product’s viscosity. In nearly all production stages the viscosity of the material
has a great impact such as in the mixing process and while pumping liquids through pipes.
Viscometers are used to determine the viscosity of a fluid. The higher the viscosity
value of a fluid, the thicker it is. The elastic capacity of a fluid is called viscosity. Rotational
viscometers are perfectly suited for the determination of the viscosity of a wide range of
different samples. Liquid up to semi-solid samples are suitable for viscosity testing with
rotational viscometers. For each torque model different spindles exist so that samples with
different viscosities can be measured. Usually interchangeable spindles in the form of disks
and cylinders are used. They are fixed on the coupling of the instrument. For a given
viscosity the flow resistance is related to the spindle’s speed of rotation and its shape and
size. R/H-instrument usually contains six spindles.
Please add references in your introduction!
MATERIAL AND APPARATUS
Brookfield Viscometer, beakers, sample such as Red Horse and Starjuice.
PROCEDURE
1. Effect of different speed selections on sample measurement.
a. Approximately 500 ml sample into a 1 L beaker.
b. The viscometer Model used and fix spindle# to use for the sample was recorded.
c. The dial reading was taken and the viscosity of the samples was calculated using
the formula below.
d. The step above was repeated by changing the speed to a different rpm and the
viscosity of the sample was measured.
e. The steps 1 until 4 was repeated for other samples.
Viscosity (centipoise) = Dial reading X Factor
2. Effect of different spindle number on sample measurement.
a. Approximately 500 ml sample into a 1 L beaker.
b. The viscometer Model used was recorded and the suitable speed was selected
based on the observations from procedure (a).
c. The dial reading was taken and the viscosity of the samples was calculated.
d. The different spindle was changed and the viscosity was measured.
e. The steps 1 until 4 was repeated for other sample.
RESULT
A. Effect of Different Speed (rpm) on Viscosity Measurement
Viscometer Model: LV
Speed (rpm)
Sample
6 (x10) 12 (x5) 30 (x2) 60 (x1)
Red 1 325.0 242.5 154.0 100.0
Horse 2 330.0 237.5 153.0 100.0
Viscosity Average ± Std Dev 327.5 ± 2.5 240.0 ± 2.5 153.5 ± 0.5 100.0 ± 0.0
Starjuice 1 710.0 452.5 200.0 100.0
Viscosity 2 720.0 455.0 200.0 100.0
Average ± Std Dev 715.0 ± 5.0 453.8 ± 1.3 200.0 ± 0.0 100.0 ± 0.0
Spindle#: 1
Table 1.0: Effect of Different Speed (rpm) on Viscosity Measurement
B. Effect of Different Spindle# on Viscosity Measurement
Viscometer Model: LV
Spindle#
Sample
1 (x10) 2 (x50) 3 (x200) 4 (x1000)
Red Horse 1 325.0 325.0 200.0 200.0
Viscosity 2 330.0 325.0 400.0 200.0
Average ± Std Dev 327.5 ± 2.5 325.0 ± 0.0 300.0 ± 100.0 200.0 ± 0.0
Starjuice 1 710.0 775.0 900.0 1000.0
Viscosity 2 720.0 750.0 800.0 900.0
Average ± Std Dev 715.0 ± 5.0 762.5 ± 12.5 850.0 ± 50.0 950.0 ± 50.0
Spindle#: 1
Table 1.1: Effect of Different Different Spindle# on Viscosity Measurement
CALCULATION
1. Effect of speed on viscosity
Viscosity of sample using spindle 1
Viscosity (centipoise) = Dial reading × Factor
Table 2.0 Viscosity of RED HORSE
Speed 6.0 12.0 30.0 60.0
(rpm)
Viscosity 327.5 x10 240.0 x 5 153.5 x 2 100.0 x 1
(Cp) = 375 = 1200 = 307 = 100.0
Table 2.1 Viscosity of STAR JUICE
Speed 6.0 12.0 30.0 60.0
(rpm)
Viscosity 715.0 x 10 453.8 x 5 200.0 x 2 100.0 x 1
(Cp) = 7150 = 2269 = 400 = 100
Effect of different speed on viscosity measurement
1200
1000
800
600
400
200
0
6 (x10) 12 (x5) 30 (x2) 60 (x1)
Red Horse Viscosity Starjuice Viscosity
Figure 2.2: Graph of effect of different speed on viscosity measurement
2. Effect of spindle number on viscosity
Speed = 6 rpm
Table 3.0 Viscosity of RED HORSE
Spindle # 1 2 3 4
Viscosity 327.5 x 10 325.0 x 50 300.0 200 x
x 200 1000
(Cp) = 3275 = 16250
= 60000 = 200000
Table 3.1 Viscosity of STAR JUICE
Spindle # 1 2 3 4
Viscosity 715.0 x 10 762.5 x 50 850.0 x 950.0 x
200 1000
(Cp) = 7150 = 38125
= = 950000
170000
Effect of different spindle number on viscosity measurement
1000
900
800
700
600
500
400
300
200
100
0
1 (x10) 2 (x50) 3 (x200) 4 (x1000)
Red Horse Viscosity Starjuice Viscosity
Figure 3.2: Graph of effect of different spindle number on viscosity measurement
DISCUSSION
In this experiment, there were two types of samples used which were Redhorse and
Starjuice. The viscosity of the sample was measured using different speed and number of
spindles. The speed used were 6, 12, 30 and 60 while for the number of spindles used were 1,
2, 3 and 4. Viscosity is a measure of the resistance of a fluid to deformation under shear
stress.
Based on the result obtained, for the Redhorse, the viscosity measurement (centipoise)
for different speed such as 6, 12, 30 and 60 were 375, 1200, 307 and 100.0 while for Starjuice
were 7150, 2269, 400 and 100. From the graph that had been plotted, the higher the speed,
the lower the viscosity measurement. The graph showed the decreasing trend for both sample
which were Redhorse and Starjuice. The viscosity measurement (centipoise) for different
number of spindle used such as 1, 2, 3, and 4 for Redhorse were 3275, 16250, 60000, 200000
while for the Starjuice were 7150, 38125, 170000 and 950000. From the both graph that had
been plotted, the Starjuice is higher than Redhorse. So, Starjuice is more concentrated than
Redhorse. Solution viscosity for electrospinning can generally be increased by using a more
concentrated solution. A more concentrated drug solution tends to be more viscous. A fluid
with large viscosity resists motion because its molecular makeup gives it a lot of internal
friction (reference?). A fluid with low viscosity flows easily because its molecular makeup
results in very little friction when it is in motion.
The result obtained for effect of different speed (rpm) on viscosity measurement
(centipoise) using spindle number 1, for Redhorse were 327.5, 325.0, 300.0, 200.0 while for
the Starjuice were 715.0, 762.5,400 and 100. The result obtained for effect of different
spindle number on viscosity measurement(centipoise) using speed 6 rpm, for Redhorse was
3275, 240.0, 153.5, 100 while for Starjuice were 715.0, , 200.0, 453.8 100.0. The
Redhorse have lower viscosity than Starjuice, so it should use the highest speed to determine
the viscosity compare to Starjuice. The flow resistance increases with the speed and size of
the spindle. The lowest viscosity range can be covered by measuring with the biggest spindle
at maximum speed. The highest viscosity range can be covered by measuring with the
smallest spindle at the lowest speed. The higher the viscosity value of a fluid, the thicker it is.
For a better reproducibility the same spindle and speed combination should be used
for multiple tests. If the viscosity of the sample is unknown, the viscosity is tested by taking
the smallest spindle first and replacing it in ascending order by the next larger spindle until a
valid measurement result is achieved. To obtain a valid measurement the torque value must
be between 10 % and 100 %. If the torque value is higher than 100 %, a smaller spindle has
to be used. If the torque value is lower than 10 %, a bigger spindle has to be used
(reference?). The higher the torque value the better the accuracy is, since the accuracy of the
measuring system depends on the full scale range (usually 1 % of FSR) (reference?).
Please add more discussion on previous published studies for comparison
CONCLUSION
In conclusion, the viscosity of the sample had been determined based on different
speed and spindle and the application of viscometer also determined. Starjuice is more
concentrated than Redhorse because it have higher viscosity than Redhorse. The lowest
viscosity range can be covered by measuring with the biggest spindle at maximum speed. The
highest viscosity range can be covered by measuring with the smallest spindle at the lowest
speed.
REFERENCE (Please follow APA style)
Mezger, T. (2011). The Rheology Handbook. 3rd Edition. Hanover: Vincentz Network, pp:
40-45.
Bloomfield, V, A. & Dewan, R, K. (2000), Viscosity of liquid mixtures. Journal of Physical
Chemistry. pp: 3113-3115.
LI, S. e. (2012). The viscosity distribution around a rising bubble in shear-thinning non-
newtonian fluids. Brazillian Journal of Chemical Engineering, 265-274.
