FDS308 Food Technology: Practical Report on Food Viscosity

This practical report details experiments on food viscosity, focusing on the effects of temperature and hydrocolloids. The study investigates the viscosity of honey and gravy at varying temperatures, along with the formulation and viscosity assessment of food products. Furthermore, it explores the impact of different hydrocolloids, such as sodium alginate and xanthan gum, on liquid viscosity. The report presents the methods, materials, and results, including tabular and graphical representations of the data. It discusses the findings, implications, and limitations of the experiments, drawing conclusions about the factors influencing food viscosity and the role of hydrocolloids as thickening agents. The report adheres to the structure of a formal scientific report, including an introduction, materials and methods, results, discussion, conclusion, and references.

Running head; Practical Report 5
Practical Exercise 5
Viscosity measurement of Foods
University
Name of the student:

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Table of Contents
Introduction....................................................................................................................................4
Methods and materials...................................................................................................................5
Results............................................................................................................................................6
Discussion......................................................................................................................................8
Conclusion.....................................................................................................................................9
References....................................................................................................................................10
List of tables
Table 1 Table showing viscosity rates on different temperature measurements.......................6
Table 2Graphical presentation of the temperature and viscosity rate...................................of 6
Table 3 Showing rate of viscosity on hydrocolloids substance.................................................7

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Table 4 Viscosity for the formulation of food products............................................................7

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Introduction
Viscosity is an important aspect of fluids. Viscosity relates to the internal friction of a
liquid and its ability to resist flow. Internal friction is often observed through stirring of the
liquid to create a vortex. Vortex is stopped gradually and the rotation for a liquid is stopped.
This is due to the frictional force which is present in the liquid which the liquid has to
overcome in order for the liquid to flow, (Mule & Kulakami, 2016). Food viscosity is an
important aspect of enhancing the thickness of liquids. Viscosity characterizes food texture.
Food product viscosity is essential and hence must be controlled and measured to enhance
consistency. Liquid foods have been shown to have high sensitivity on breakdown structure
due to the sheer application. Liquids exhibit different behaviors. Newton behavior is observed
in simple liquids, having small molecules which don’t interact in a connected structure,
however long chain polymers have been shown to have a low concentration. Liquids
viscosity is often depended on the sheer materials used, a high shear rate used on the fluid
thinner compared with liquid sheared slowly, (Messadi et al., 2015).
This reflects steady state dependency also referred to as pseudoplastic. Fluids further
can exhibit thixotropy which is a shear thinning of the original material which increases shear
rates and being depended on the sheer duration. Fluids often display a larger more complex
association often have more viscosity levels, (Wu, Ding, Jia & He, 2015). This has been
observed with long-chain polymers which are found in foods such as proteins, starches,
gums, and hydrocolloids. Further, these materials often have chemical groups of hydroxyl
groups which exist along the length of polymer which hydrophilic. Polymer chains often are
entangled on one another forming networks which trap and immobilize the water.
Viscosity further depended on the concentration and relationships. However, these
relationships are not linear. A small increase in hydrocolloid concentration often increases
viscosity, which when an increase in concentration can have an exponential increase in the
viscosity. Addition of starch has an effect on the viscosity of liquids, (Chen & Bonaccurso,
2014). Hydrocolloid systems have high water binding capacities which generate lower
viscosity at low concentrations.
Temperature is a crucial factor on viscosity rate. It has major effects on the viscosity
which decreases significantly with increasing temperature. With the increase in temperature,

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molecules of the substances move and spend less time being in contact with each other,
(MacClements, 2015). In the industrial production process, there exist numerous instruments
which are used to measure viscosity. Simple apparatus are the Bostwick viscometer which
determines the viscosity of food through measuring the flow distance of fluids. Food samples
which stick together display high viscosity and don’t flow evenly in 30 seconds and are not
adapted to the instrument. A key disadvantage of this apparatus is factors such as the surface
tension of the food material, which can have an influence on the results but provide a quick
way of controlling a number of foods, (Zhang, Tong, Decker& McClements, 2015).
Viscosity plays a critical role in quality control of food products. It is essential in
differentiating raw quality and eliminating further processing activity. Food viscosity in foods
is an important aspect which plays a critical role during processing and for enhancing textual
properties in food. A big rand of techniques is available for assessing viscosity, (Rao, 2014).
This experiment sought to find out three experimental parts of food viscosity. The first
experiment sought to find the effect of temperature on the viscosity of liquid foods in this
case honey and gravy. Viscosity was measured using viscometer. Secondly, food product was
formulated using products such as sugar, fruit juice concentrate, xanthan powder, and citric
acid. After this formulation was made, its viscosity status was assessed. Finally effected of
selected hydrocolloids and solution viscosity was assessed using a viscometer.
Methods and materials
In the first experiment, the materials used included honey, gravy and water baths set at
20, 40 and 60 degrees centigrade. 180 ml of the Liquid substance was transferred to 200 ml
containers and equilibrated at the different set temperatures. Then viscometer was used to
measure the viscosity trends of the liquids set at different temperatures.
The second method used fruit juice, agar, citric acid, xanthan powder, jars, and
magnetic stir. The juice formula was at the following wet table weight percentage;
Fruit juice concentrate
Citric acid 10%w/w
Sugar 1%w/w
Xanthan 0.25%w/w

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Water measured at 100g
The products were weighed to prepare 100 g of juice solution, water is added on top of
the pan and citric acid dissolved with the sugar through stirring and juice concentrate added
and mixed thoroughly. The xanthan powder was added and stirred vigorously and final
weight made to 100 g and the viscosity measured.
Lastly, the effects of hydrocolloid concentration viscosity were measured. Materials
needed to include sodium alginate both type 1 and 2 at 2%w/w solution, xanthan 2% w/w
solution, jars and viscometer. The diluted solutions were prepared with the allocate sodium
alginate sock solution, with each solution diluted weighing 80g and their concentrations were
0.25% w/w, 0.5%w/w and 1% w/w. Then thereafter their viscosity was measured using the
viscometer.
Results
Part a
Effect of temperature on viscosity of honey and gravy
Honey Gravy
Temper
ature
Rate per minute mPa.s mPa.s
200c 5 1760 1139
10 1722 681
15 1728 503
400c 5 268 1110
10 268 615
15 268 452
600c 5 70 960
10 64 524
15 68 369
Table 1 Table showing viscosity rates on different temperature measurements

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Rate per minute
5
10
15
5
10
15
5
10
15
Temper
ature 20c 40c 60c
0
200
400
600
800
1000
1200
1400
1600
1800
Honey
Gravy
Series3
Table 2Graphical presentation of the temperature and viscosity rate
Part b
Concentration (%
w/w)
Viscosity mpas
Sodium Alginate type 1 2 6.7
1 1.0
0.5 0.32
0.25 0.15
Sodium alginate type 2 2 247
1 29
0.5 9
0.25 4
xanthan 2 116
1 56.9
0.5 24.6
0.25 10.2
Table 3 Showing rate of viscosity on hydrocolloids substance
Part c

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Hydrocolloid Xantham gum at a viscosity rate if 100 rpm at room temperature
Concentrations (% w/w) Weight stock (g) Weight water (g) Viscosity
2 80 0 116
1 40 40 56.9
0.5 20 60 24.6
0.25 10 70 10.2
Table 4 Viscosity for the formulation of food products
Discussion
Liquid viscosity increases with temperature increase. This was exhibited in the
experiment whereby the rate of flow at 20 degrees centigrade tend to increase as the
temperature of the liquid was increased. Increasing rate per minutes illustrated higher
viscosity flow rate compared to a high rate per minutes as exhibited in the results above.
Honey exhibited high viscosity rate compared to gravy when there was temperature increase.
Liquids exhibit a molecular interchange which is exacerbated by the cohesive forces n
the molecule. Both the molecular interchange and cohesion contribute significantly to the
viscosity rate. Impact of temperature increase on the liquid thus decrease the cohesive forces
and alternatively increasing the rate of molecular interchange, (Erdogdu, Tutar, Sargini &
Skipnes, 2017). When the temperature was increased, thermal energy tends to increase and
the molecules become more mobile. This reduces the binding energy and thus viscosity is
reduced. Continuous heating of the liquid tends to increase the liquid kinetic energy and
exceed the binding energy, (Rao, 2014).
Assessment of Sodium Alginate and xanthan shows that type 1 displayed a high
viscosity rate compared to type alginate sodium alginate. Type 2 sodium alginate shows to
have high viscosity rate compared to xanthan and sodium alginate type 2.alginate has been
predominantly been used in the pharmaceutical industries as an aqueous solution and
thickening agent. It is an essential component of biopolymer for enhancing intrinsic viscosity,
(Konadakci, Ang & Zhou, 2015).
Xanthan, a gum by its chemical properties reveal an average viscosity rate depending
on the concentration of wettable weight. The lower the wettable weigh contrite the lower the

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viscosity rate. Xanthan has been utilized commercially as a thickener and stabilizer in various
biochemical reactions, (Agoub et al., 2007).
The present study shows the beneficial effects of xanthan as a gum and its effects on
being an emulsified and viscosity enhancer. Xanathan usage in food processing industries
plays a crucial role in enhancing viscosity and liquid flow.
Hydrocolloid polymers are hydrophilic in nature and contain many hydroxyl groups.
They are effective in controlling aqueous food properties through enhancing viscosity. In this
experiment xanthan viscosity assessment was tested with varying wettable weigh
concentration, (Li & Nie, 2016). The study results revealed that the lesser the concentration
of w/w, the lower viscosity rate. It is for this reason that hydrocolloids agents such as xanthan
which is long-chain polymers are effective in forming an affinity for binding effect on water
molecules hence increasing viscosity, (Koocheki, Ghandi, Razavi, Mortazavi & Vasiljevic,
2009).
Hydrocolloids effects are beneficial in that they function as thickening, emulsifying and
stabilizing agents in food, (Akima et al., 2017). This experimental study exhibited how
hydrocolloid concentration has effects on the viscosity rate of xantham.
Conclusion
Liquids viscosity is a crucial aspect when it comes to foods. Viscosity plays an
important aspect as a thickening agent of food. Hydrocolloid properties on agents are
essential as a thickening and emulsifying agents. Viscosity is affected by factors such as
temperature and hydrocolloids. This experiment has shown that increasing the temperature
rate of liquids tend to lower the viscosity rate while increasing hydrocolloid concentration
increases viscosity rate of liquids. Thus temperature and hydrocolloid presence affect
viscosity rates of fluids.

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References
Agoub, A. A., Smith, A. M., Giannouli, P., Richardson, R. K., & Morris, E. R. (2007). “Melt-
in-the-mouth” gels from mixtures of xanthan and konjac glucomannan under acidic
conditions: A rheological and calorimetric study of the mechanism of synergistic
gelation. Carbohydrate polymers, 69(4), 713-724.
Akima, A., Yamagata, A., Hasegawa-Tanigome, A., Kumagai, H., & Kumagai, H. (2017).
Viscosity and Hardness of Food Hydrocolloids and Their Relation with Velocity
through the Pharynx. JOURNAL OF THE JAPANESE SOCIETY FOR FOOD
SCIENCE AND TECHNOLOGY-NIPPON SHOKUHIN KAGAKU KOGAKU KAISHI,
64(3), 123-131.
Chen, L., & Bonaccurso, E. (2014). Effects of surface wettability and liquid viscosity on the
dynamic wetting of individual drops. Physical Review E, 90(2), 022401.
Erdogdu, F., Tutar, M., Sarghini, F., & Skipnes, D. (2017). Effects of viscosity and agitation
rate on temperature and flow field in cans during reciprocal agitation. Journal of Food
Engineering, 213, 76-88.
Kondakci, T., Ang, A. M. Y., & Zhou, W. (2015). Impact of sodium alginate and xanthan
gum on the quality of steamed bread made from frozen dough. Cereal Chemistry,
92(3), 236-245.
Koocheki, A., Ghandi, A., Razavi, S. M., Mortazavi, S. A., & Vasiljevic, T. (2009). The
rheological properties of ketchup as a function of different hydrocolloids and
temperature. International journal of food science & technology, 44(3), 596-602.
Li, J. M., & Nie, S. P. (2016). The functional and nutritional aspects of hydrocolloids in
foods. Food Hydrocolloids, 53, 46-61.
McClements, D. J. (2015). Food emulsions: principles, practices, and techniques. CRC press.
Messaâdi, A., Dhouibi, N., Hamda, H., Belgacem, F. B. M., Adbelkader, Y. H., Ouerfelli, N.,
& Hamzaoui, A. H. (2015). A new equation relating the viscosity Arrhenius
temperature and the activation energy for some Newtonian classical solvents. Journal

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of Chemistry, 2015.
Mule, G. M., & Kulkarni, A. A. (2016). Mixing of medium viscosity liquids in a stirred tank
with fractal impeller. Theoretical Foundations of Chemical Engineering, 50(6), 914-
921.
Rao, M. A. (2014). Flow and functional models for rheological properties of fluid foods. In
Rheology of Fluid, Semisolid, and Solid Foods (pp. 27-61). Springer, Boston, MA.
Wu, Y., Ding, W., Jia, L., & He, Q. (2015). The rheological properties of tara gum
(Caesalpinia spinosa). Food Chemistry, 168, 366-371.
Zhang, Z., Zhang, R., Tong, Q., Decker, E. A., & McClements, D. J. (2015). Food-grade
filled hydrogels for oral delivery of lipophilic active ingredients: Temperature-triggered
release microgels. Food Research International, 69, 274-280.