UNIVERSITY OF CINCINNATI


Date:___________________


I, _________________________________________________________,
hereby submit this work as part of the requirements for the degree of:

in:

It is entitled:







This work and its defense approved by:


Chair:
_______________________________

_______________________________

_______________________________

_______________________________

_______________________________

10/24/2007
Robert B. Wieland
Master of Science
Chemistry
Preparation of Calcium Alginate and Calcium Pectinate Films
and Determinations of Their Permeabilities
Dr. James E. Mark
Dr. Estel Sprague
Dr. Carl Seliskar
Preparation of Calcium Alginate and Calcium Pectinate Films and
Determinations of Their Permeabilities

A dissertation to the
Graduate School
of the University of Cincinnati
in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE
in the Department of Chemistry

by

Robert B. Wieland
Bachelors of Science in Chemical Technology
University of Cincinnati, June 2001


Committee Chair: Dr. James E. Mark





ABSTRACT
Small amounts of polymers are typically used in flavor and food applications.
Polymers are typically applied in thin coatings which allow for a cost-effective
encapsulation with desirable barrier properties. Understanding the properties of thin
barrier coatings is essential to obtaining optimal encapsulation performance. Many of
the polymers used in the flavor and food industry are cross-linked hydrogels, which
are water insoluble but water swellable. Hydrogel barriers allow water soluble
components to be extracted from the encapsulation system. Flavor components
having a large affinity for water will be extracted from the encapsulation system while
more hydrophobic flavor components will remain encapsulated. Preferential flavor
extraction is a large problem for the flavor industry because flavors are complicated
mixtures of both hydrophilic and hydrophobic components.
Understanding diffusion and permeability coefficients is desirable for creating
optimized encapsulation systems. However, creating thin uniform films reproducibly
can be challenging and expensive. In the past, thick polymer films were cast onto a
metal sheet and cross-linked with the appropriate chemicals. The method produced
wrinkled and inconsistent film thicknesses. The inconsistent films produced
irreproducible diffusion and permeability coefficient data. New testing methods were
developed to understand flavor partitioning across thin hydrogel membranes. One
focus of the present work was to create 10μm to 50μm polymer films reproducibly
with uniform thicknesses. The second focus of this project was to determine thin film
diffusion and permeability coefficients of the created polymer films.
The first portion of this thesis discusses the creation of thin polymer films. Calcium

ii


alginate and calcium pectinate films were created using a lightly scuffed metal sheet.
The sheet was then used in a leveling apparatus which provided a level surface for
film casting. The polymer films were characterized by micrometer measurement,
environmental scanning electron microscopy (ESEM) and swelling ratio experiments.
Micrometer measurements demonstrated the successful preparation of 21 to 23 (+/-
1) μm calcium alginate films and 19 to 20 (+/- 1) μm calcium pectinate films. The 4 to
6% relative standard deviation was considered acceptable for the present work. The
calcium alginate and calcium pectinate films were also analyzed by ESEM. Both
sides of the films were analyzed at 200X and 1500X magnifications. The polymer
film surface exposed to the scuffed metal sheet produced a rough and irregular
surface. The polymer film surface not exposed to the scuffed metal sheet had a
smooth and uniform surface. Film thickness measurements were also performed
using the ESEM computer software to further verify the film thickness measurements
obtained from the micrometer. The ESEM film thickness measurements
demonstrated a 20.9 (+/- 1.1) μm calcium alginate film and a 20.2 (+/- 0.7) μm
calcium pectinate film had been produced. Both films demonstrated an average
relative standard deviation of 4 to 6% which was considered acceptable for the
present work. The ESEM measurements of film thickness demonstrate the
methodology for creating thin polymer films is reproducible and within the desired
thickness range. However, the scuffed metal sheet creates films that are rough on
one side and smooth on the other side. Preliminary polymer swelling ratio
experiments in distilled water showed calcium alginate films swell to 2.4 times their
original dry weight and calcium pectinate films swell by a factor of 3.8. The large

iii

swelling ratios for the films indicated that distilled water was an appropriate solvent
for determining film permeability and diffusion coefficients.
The second portion of this thesis focused on determining film diffusion and
permeability coefficients. A new thin-film diffusion cell (TFD) was built and coupled to

a UV/VIS spectrophotometer fitted with a fiber optic probe which allowed for in-situ
measurement of analytes which absorb ultraviolet radiation such as benzaldehyde.
Permeability measurements using benzaldehyde demonstrated a permeability
coefficient of 3X 10
-5
cm/sec. (+/- 5%) for the 22 (+/- 1) μm calcium alginate film and 2
X 10
-4
cm/sec. (+/-6%) for the 20 (+/- 1) μm calcium pectinate film. Diffusion
coefficients were then calculated for the two films. The diffusion coefficient for a 22
(+/-1) μm calcium alginate film was 6.5 X 10
-8
(+/- 11%) cm
2
/sec while the diffusion
coefficient for a 20 (+/-1) μm calcium pectinate film was 3.9 X 10
-7
(+/- 12%) cm
2
/sec.
The relative standard deviations for the permeability and diffusion coefficients were
considered acceptable for this study. The permeability and diffusion coefficients
indicated a calcium pectinate film is more permeable than a calcium alginate film of
equal thickness.









iv


ACKNOWLEDGEMENTS
I would like to express my gratitude to Dr. Dave Siegel for the guidance and support
shown to me while obtaining a graduate degree. I acknowledge my graduate
achievement would not have been possible without the patience, flexibility and
understanding shown by this man. I would also like to thank Dr. Robert Eilerman for
his flexibility allowing me to achieve an academic milestone while maintaining full
time duties at the Givaudan Flavor Corporation.
I would like to acknowledge the financial support of the Givaudan Flavor
Corporation. The financial support allowed for critical glassware to be purchased and
allowed me to obtain a graduate degree.
I would like to give a heartfelt thank you to Dr. Jing Zhang for helping me understand
diffusion and permeability. In this way, Dr. Zhang helped me become a better
chemist with an increased knowledge of polymer systems.
I appreciate the guidance Dr. James Mark has given while writing my graduate thesis
and during my academic career. His insight has been valuable and informative.
I would like to thank my mother Brenda Wilson for her endless encouragement. Your
determination, work ethic and loving support has enabled me to be successful in the
workplace and in academia.
I am grateful for the support and encouragement shown by my wife Jessica Wieland.
Without her support this achievement would not be possible. Thank you for
understanding the extra hours at school and the extra hours of homework which kept
us apart. I could not ask for a more supportive and inspiring wife.


v


TABLE OF CONTENTS
ABSTRACT……………………………………………………………………………….… ii
ACKNOWLEDGEMENTS……………………………………………………………….… v
TABLE OF CONTENTS………………………………………………………………….…vi
LIST OF FIGURES……………….…………………………… …………………… … viii
LIST OF TABLES……………… …………………………… ……………….………… xi
1. INTRODUCTION…………………………………………………………………………1
1.1: Pectin: Sourcing, Manufacture and Functionality……………………………… 5
1.2: Pectin: Structure…………………………………………………………………….7
1.3: Alginate: Sourcing, Manufacture and Functionality……………………………. 8
1.4: Alginate: Structure…………………………………….………… ………………10
2. EXPERIMENTAL SECTION………………………………………………………… 12
2.1: Experimental Objectives………………………………………………………….12
2.2: Raw Materials…………………………………………………………… ……….13
2.3: Procedures………………………………………… …………………………….14
2.3.1: Film Sheet Preparation………………………………………………… …….14
2.3.2: Leveling Film Sheet Apparatus……………………………………………… 15
2.4: Procedures-Sample Preparation……………………………………………… 16
2.4.1: Creating 1.0% Sodium Alginate Solutions……………………………………16
2.4.2: Creating Calcium Alginate Films………………………………………………17
2.4.3: Creating 1.0% Pectin Solutions 18
2.4.4: Creating Calcium Pectinate Films…………………………………………… 18
2.4.5: Creating 1000PPM Benzaldehyde Standards in Miglyol 812………………20

vi

2.4.6: Creating Benzaldehyde Standards in Distilled Water………………….……20
2.5: Characterization Techniques…………………………………………………….21
2.5.1: Micrometer Measurements……………… 21

2.5.2: Environmental Scanning Electron Microscopy (ESEM)….….….…….…….22
2.5.3: Swelling Ratio Measurement (SR) 22
2.5.4: Polymer Film Diffusion Analysis……………………………………….………23
2.5.4.1: UV/VIS Absorbance Linear Regression Calibration….….…………….….23
2.5.4.2: UV/VIS Thin Film Diffusion Analysis (TFD)……………………………… 24
3. RESULTS and DISCUSSION…………………………………………………………27
3.1: Micrometer Measurements…………………… 27
3.2: Environmental Scanning Electron Microscopy (ESEM)……….….….……….28
3.3: Swelling Ratio Measurement (SR) 31
3.4: Polymer Film Diffusion Analysis………….…………………………… ………33
3.4.1: UV/VIS Absorbance Linear Regression Calibration….….………………….33
3.4.2: UV/VIS Thin Film Diffusion Analysis (TFD)…………….….………… …….35
4. CONCLUSIONS……………………………………………………… ……………….38








vii

LIST OF FIGURES
Figure 1.2-1: Structure of the pectin molecule……………………………………………7
Figure 1.2-2: Structure of the calcium pectinate molecule……………….…………… 8
Figure 1.4-1: Alginate monomers…………… …………………………………………. 10
Figure 1.4-2: Alginate block types…………………………………………………… 11
Figure 1.4-3: Calcium binding site in polyguluronate dimer… …………………… 12
Figure 1.4-4: Calcium alginate cross-linked “Egg box” model………………………… 12

Figure 2.2-1: Structure of benzaldehyde… …………………….…………………… 14
Figure 2.3.1-1: Scuffed cookie sheet…………………………………………………… 15
Figure 2.3.2-1: Leveling film apparatus with key measurements………….………… 16
Figure 2.3.2-2: Leveling film apparatus containing film sheets……………………… 16
Figure 2.4.2-1: 20μm calcium alginate film……………………………………… ….…18
Figure 2.4.4-1: 20μm calcium pectinate film………………………………………….…19
Figure 2.5.4.1-1: UV/VIS spectrophotometer……………… ……………………… 23
Figure 2.5.4.1-2: Fiber optic probe fitted with UV/VIS spectrophotometer…… … 24
Figure 2.5.4.2-1: Schematic of thin film diffusion (TFD) apparatus…….…………… 25
Figure 3.2-1: ESEM analysis of calcium alginate and pectinate rough film side…… 29
Figure 3.2-2: ESEM analysis of calcium alginate and pectinate smooth film side …. 30
Figure 3.4.1-1: Linear regression chart for benzaldehyde standards……….………. 35
Figure 3.4.2-1: Permeability coefficient for calcium alginate film…….……….………. 37
Figure 3.4.2-2: Permeability coefficient for calcium alginate film………………… …37



viii

LIST OF TABLES
Table 1: Benzaldehyde standard dilutions……………………………………………….21
Table 2: Micrometer measurements for thin calcium alginate films……… 28
Table 3: Micrometer measurements for thin calcium pectinate films……… ………. 28
Table 4: Calcium alginate film thickness measurements by ESEM analysis……… 31
Table 5: Calcium pectinate film thickness measurements by ESEM analysis … 31
Table 6: Swelling ratio measurements of calcium alginate thin films…………….… 33
Table 7: Swelling ratio measurements of calcium pectinate thin films …………… 33
Table 8: Average absorbance values of benzaldehyde standards………… 34
Table 9: Benzaldehyde absorbance measurements across calcium alginate films 34
Table 10: Benzaldehyde absorbance measurements across calcium alginate films.34













ix

1. INTRODUCTION
Both flavors and active ingredients such as vitamins impart important characteristics
to products desirable to consumers in the marketplace. However, flavors and active
ingredients can be lost or degraded during food processing, with the result of losing
consumer benefit. However, critical components can be encapsulated using
polymeric materials to prevent such losses. Polymers are typically applied in thin
coatings which allows for a cost effective encapsulation with functional properties
1
.
Understanding the properties of thin barrier coatings is essential to obtain optimal
encapsulation performance. The food and flavor industry have used polymeric
materials for decades as bulking agents, viscosifiers, and barrier materials for various
encapsulation systems. Materials such as sugar, maltodextrin, pectin and alginate
can be used to create water soluble encapsulation systems
2
. Pectin and alginate

materials are of great interest to the flavor industry due to the cross-linkable nature of
these natural polymer materials
3
. Cross-linked pectin and alginate form hydrogel
barriers which are water insoluble but water swellable
4
. The swelling properties of
hydrogel barriers can be manipulated by varying levels of chemical cross-linking
along these carbohydrate chains
5
. Highly cross-linked polymer materials typically
demonstrate minimized diffusion properties which creates an effective barrier
reducing flavor loss during cooking processes. Lightly cross-linked polymers become

1
Gutcho, M.H. Microcapsules and Other Capsules. Noyes Data Corporation: Park Ridge, NJ, 1979.
2
Risch, S.J. (1995). Encapsulation: Overview of Uses and Techniques. In Risch, S.J. and Reineccius,
G.A. (Ed.) Encapsulation and Controlled Release of Food Ingredients (pp 2-7). Washington, DC:
American Chemical Society.
3
Schlemmor, U. (1989) Studies of the binding of copper, zinc and calcium to pectin, alginate,
carrageenan and gum guar in HCO
-
3
– CO
2
buffer. Food Chemistry, 32 (3), pg 223-234.
4
Bajpai, S.K.; Sharma, S. (2004) Investigation of swelling/degradation behavior of alginate beads

crosslinked with Ca
2+
and Ba
2+
ions. Reactive & Functional Polymers, 59 (2004), pg 129-140.
5
Flory, P.J. Principles of Polymer Chemistry. Cornell University Press: Ithaca, NY, 1953.

1

less effective barriers due to increased diffusion properties.
Flavor encapsulation systems containing hydrogels have been utilized in food to
create products with increased flavor perception
6,7
. However, flavors encapsulated in
hydrogel systems typically need to be reformulated to preserve such a desirable
perception. The swelling property of hydrogel barriers allows flavor components
having a large affinity for water to be extracted from the encapsulation system while
more hydrophobic flavor components remain encapsulated. The swelling property of
hydrogel barriers is a large problem for the flavor industry because flavors are
complicated mixtures of both hydrophilic and hydrophobic components. For
example, typical fruit flavors contain numerous individual ingredients which impart a
delicate balance and flavor profile. Individual cherry flavor ingredients have
vegetable oil:water partition coefficients ranging from 4 to 1. A partition coefficient,
denoted as P in this document, is the concentration ratio of a compound in two
immiscible solvents at equilibrium
8,9
. The P coefficient in this study is a measure of
differential compound solubility between vegetable oil and water. The higher the P
value the more hydrophobic the compound. Since most food applications are

exposed to water over time, maintaining a balanced flavor profile is difficult. Creating

6
Soper, J.C. (1995). Utilization of Coacervated Flavors. In Risch, S.J. and Reineccius, G.A. (Ed.)
Encapsulation and Controlled Release of Food Ingredients (pp 104-112). Washington, DC: American
Chemical Society.
7
King, A.H. (1995). Encapsulation of Food Ingredients: A Review of Available Technology, Focusing
on Hydrocolloids. In Risch, S.J. and Reineccius, G.A. (Ed.) Encapsulation and Controlled Release of
Food Ingredients (pp 26-37). Washington, DC: American Chemical Society.
8
Seuvre, A.; Philippe, E.; Rochard, S. and Voilley, A. (2006) Retention of aroma compounds in food
matrices of similar rheological behavior and different compositions. Food Chemistry, 96 (1), pg 104-
114.
9
Roberts, D.D. (1998). Relationship Between Aroma Compounds’ Partitioning Constants and Release
During Microwave Heating. In Mussinan, C.J. and Morello, M.J. (Ed.) Flavor Analysis Developments in
Isolation and Characterization (pp 61-68). Washington, DC: American Chemical Society.


2

an encapsulation system with reduced flavor diffusion properties would be beneficial
for the flavor industry.
The flavor industry creates encapsulation systems to address various food
processing issues. Analyzing an encapsulation system typically entails “in-use” tests
which only demonstrate whether or not the encapsulation system provides a
benefit
10
. A typical “in-use” test consists of making an encapsulation containing a

flavor. The encapsulated flavor is then added to a food application and processed
under normal cooking conditions. These tests only provide a result which is negative
or positive. Since the encapsulation system is a complex product no data is provided
on what aspect of the technology is providing the result. Also, the food application is
very complex and also affects how the encapsulation performs. These facts leave
the researcher asking “Have we created a better encapsulation or merely used the
encapsulation in a more desirable environment?”
Analytical experiments, such as encapsulation-dissolution testing, have been created
to characterize the individual encapsulation systems in model food application
environments. Valuable data has thus been obtained which can predict
encapsulation performance in various applications
11
. However, encapsulation
performance is highly dependent on capsule particle size, polymer barrier thickness,
polymer permeability, capsule structure and encapsulation makeup. Capsule
performance is measured, with account for all the variables that affect encapsulation
performance.

10
Mark, J.E.; Allcock, H.R.; West, R. Inorganic Polymers. 2
nd
ed. Oxford University Press: New York,
NY, 2005.
11
Martin, C.A., (2003) Evaluating the Utility of Fiber Optic Analysis for Dissolution Testing of Drug
Products. Dissolution Technologies, pg 37-39.

3

Previously at the Givaudan Flavor Corporation attempts were made to study the

diffusion and permeability properties of hydrogel films containing clay
12
. Films
approximately 25 to 200 microns were cast and cross-linked with the appropriate
reagents. The method produced wrinkled films and inconsistent film thicknesses that
only allowed for small pieces of the films to be analyzed. The irregular films
produced irreproducible diffusion and permeability measurements. The analytical
methodology used to characterize the films was tedious and involved the use of
multiple analytical techniques. Each analytical technique contributed compounded
errors which affected the accuracy of the data.
The primary goal of the present study is to create thin hydrogel films whose diffusion
and permeability properties can be measured easily with relative accuracy.
Understanding flavor diffusion across thin hydrogel membranes will provide the basic
knowledge for hydrogel encapsulation development. The films created were
approximately 20μm thick, which replicates typical coating thicknesses used in the
flavor industry. Creating thin films can be challenging due to the following
circumstances: thin films become very brittle, brittle and cracked films lead to
ineffective barriers, and thin films are hard to cast uniformly. The thin films created
were uniform and reproducible which ensured a robust method and reliable data.
For the present work, two calcium cross-linkable polymers were chosen for study.
Alginate and pectin were chosen for their acceptance in the food and flavor industry.
The thin film hydrogels were characterized by micrometer film thickness
measurements, Environmental Scanning Electron Microscope (ESEM), swelling ratio

12
Vale, J.M. (2004). Modification of Calcium Alginate Membranes with Montmorillonite Clay to Alter
the Diffusion Coefficient (Masters Thesis, University of Cincinnati, Department of Chemistry, 2004).

4


experiments and Thin Film Diffusion (TFD) – Ultraviolet-Visible (UV/VIS) analysis.
1.1 Pectin: Sourcing, Manufacture and Functionality
Pectin and cellulose are abundant in fruits such as oranges, lemons, limes and
apples. Pectin and cellulose associate creating a macromolecule called protopectin
which binds or absorbs water. Cellulose provides mechanical rigidity and pectin
provides flexibility in the fruit and plant stock. The mechanical properties of
protopectin allow the plant to weather environmental changes during seasonal
changes
13
.
Large farming ventures and food companies process fruits such as oranges and
apples, thus creating waste streams of citrus peel and apple pomace. The waste
streams are typically created in the regional areas where the crop is grown. For
instance, large waste streams of orange peel are created in Mexico, California and
Florida. The waste streams are collected and processed to yield valuable extracts
such as pectin and cellulose.
Pectin is produced worldwide by major manufacturing companies such as Cargill and
CP Kelco. Extraction techniques performed on the citrus peel and apple pomace can
be altered to produce pectin with different functionalities. Typically, the citrus peel or
apple pomace is added to a hot acid solution where the protopectin undergoes
hydrolysis. The hydrolysis step liberates the pectin from the cellulose. The citrus
peel or apple pomace is then separated from the hot acid solution by pressing,
filtration and concentration processes. The concentrated solution is added to ethanol
where the pectin precipitates. This precipitate is then washed, dried, and milled to a

13
www.cargilltexturizing.com/products/hydrocolloids/pectins/cts_prod_hydro_pec_fun.shtml

5


specific particle size. Processing conditions are constantly being modified and
optimized to meet specific customer needs
14
.
Citrus peel and apple pommace processing allows for three types of pectin to be
manufactured. The hydrolysis processing step applied to citrus peel and apple
pomace alters the degree of esterification (DE) found in the pectin. Thermodynamic
properties such as glass transition temperature (T
g
), melting point (T
m
) and setting
rates can be drastically altered by the degree of esterification. Pectin with a DE value
greater than 50 is referred to as high-methoxyl pectin (HM)
15,16
. Typical HM-pectin’s
have a 55-85% degree of esterification and form thermostable gels in acidic pH
solutions containing 60% sugar. HM-pectin is used to stabilize milk by reducing
protein flocculation and enhancing beverage viscosities. High-methoxyl pectin has
other valuable uses such as minimizing ice crystal formation, thus enhancing
confectionary freeze-thaw properties. Pectin with a DE value below 50 is referred to
as low-methoxyl pectin (LM). Typical LM-pectin’s have a 15-45% degree of
esterification and form thermoreversible gels under acidic or basic processing
conditions. Thixotropic solutions for ice cream can be created using LM-pectin. LM-
pectin also has the ability to be crosslinked by divalent cations such as calcium and
magnesium. Crosslinked pectin typically becomes water insoluble and is useful for
film and encapsulation purposes. This pectin can also be extracted under basic
conditions using ammonia producing amidated low methoxyl pectin (LMA). Typical

14

www.cargilltexturizing.com/products/hydrocolloids/pectins/cts_prod_hydro_pec_man.shtml
15
Sharma, B.R.; Dhuldhoya, N.C.; S.U. Merchannt: U.C. Merchant. (2006). An Overview of Pectins.
Times Food Procesing Journal, June-July Issue, 44-51.


6

LMA-pectin’s have a 15-45% degree of esterification and a 5-25% degree of
amidation (DA). The addition of the amide groups to the pectin molecule changes
the rheological properties and reduces pectin’s ability to be crosslinked by divalent
cations. LMA-pectin produces thermoreversible gels which are typically used in
glazes and fruit preparations. Many different forms of pectin can be created to meet
specific customer needs. The variety of pectin’s produced allows for new and
innovative consumer products to be developed.
1.2 Pectin: Structure
Pectin is a natural polysaccharide containing up to1000 saccharide units in a chain-
like configuration. Pectin molecules have a linear backbone composed of units of (1,
4)-linked α-D-galacturonic acid and its methyl ester
17
. Figure1.2-1 illustrates the
basic structure of a pectin molecule.




α-D-galacturonic acid
Methyl ester form of galacturonic acid
α-D-galacturonic acid
Methyl ester form of galacturonic acid

Figure 1.2-1: Structure of the pectin molecule.
The galacturonic acid units may be in the salt form (galacturonate), which allows the
pectin to be an anionic polymer. The galacturonic acid residues can be esterified

17
www.cpkelco.com/food/pectin.html

7

with methanol. When 50% or more of the carboxyl groups contained in the polymer
are methylated the pectin is considered high-methoxyl pectin. This pectin is not
cross-linkable with divalent cations and has limited uses for flavor encapsulation
systems. Less than 50% methylation produces pectin which is cross-linkable with
divalent cations such as calcium
12
. Figure1.2-2 illustrates the basic structure of a
calcium pectin molecule. The pectin structure also contains L-rhamnose and
methylpentose. The addition of these sugars to the pectin polymer structure creates
a branched molecule which has much reduced linearity. The average molecular
weight of pectin is typically 50,000 to 150,000 g/mol.







+
Ca
+

+
Ca
+


+
Ca
+
+
Ca
+


+
Ca
+
+
Ca
+
Figure 1.2-2: Structure of the calcium pectinate molecule.
1.3 Alginate: Sourcing, Manufacture and Functionality
Seaweed has been used to obtain natural polymers such as alginate, agar and
carrageenan over the last 50 years. Alginate provides rigidity for the seaweed plant



8
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by association with sodium chloride in ocean water. Alginate also acts as a
humectant to reduce water loss in the plant in changing tidal conditions

18
. Alginate is
found in the Phaeophycaea brown algae family. Seaweed varieties such as
Macrocystis pyrifera, Ascophyllum Nodosum and Laminaria are useful for alginate
production
19
. Comercially important seaweed is typically harvested in the coastal
waters of California, Australia, Norway and Japan. Seaweed from different coastal
regions produces alginate with different properties due to structural differences in the
extracted polymer.
The manufacturing process to obtain alginate begins with harvesting seaweed in the
desired coastal region. Boats are built to a special design to skim the ocean surface
and retrieve the top three feet of the seaweed plant. The harvested seaweed is
gently dried and milled to desired specifications for optimal processing. The milled
seaweed is then added to hot water and sodium carbonate under mixing conditions.
The caustic treatment allows the seaweed to swell and form a viscous solution. The
highly viscous solution is diluted and the insoluble residues are removed. Chlorine is
added to the liquid fraction containing the alginate and treated with calcium chloride
to form a water insoluble precipitate. The calcium alginate is then recovered,
pressed to remove excess water and treated with a hydrochloric acid solution. The
acid-washed alginate cake is then pressed and washed with a basic solution to
produce sodium alginate which is water soluble. The solubilized alginate is then
spray dried and sieved to the desired customer specifications
20,21
.

18
Cosgrove, D.J., (2005) Growth of the plant cell wall. Molecular Cell Biology, 5, pg 850-861.
19
www.cargilltexturizing.com/products/hydrocolloids/alginates/cts_prod_hydro_alg_raw.shtml.

20
www.cargilltexturizing.com/products/hydrocolloids/alginates/cts_prod_hydro_alg_man.shtml.
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Alginate is generally used as a cold-setting gel that is thermally stable when
crosslinked. The food industry typically uses alginate as a viscosity control agent for
products such as jellies, jams, pastes, beverages, soups and ice-cream
22,23,24
.
Industries such as pharmaceutical and biomedicine companies use alginate to
encapsulate drugs and cellular materials
25
. Alginate has also been used to
dehydrate products such as paper and textiles, as flame retardants for fabrics, and as
blood detoxifiers.
1.4 Alginate: Structure
Alginate is a complex carbohydrate comprised of glucuronic and mannuronic acid
monomers. Based on the seaweed source and processing, alginate can be
produced with varying glucuronic and mannuronic acid contents
26
. Figure 1.4-1
illustrates the monomers contained in alginate.




Figure 1.4-1: Alginate monomers.
(1,4) β – D mannuronate
(1,4) α – L guluronate

(1,4) β – D mannuronate
(1,4) α – L guluronate
Alginates containing large percentages of glucuronic acid content are called high-G
  
21
www.fmcbioploymer.com/food/ingredients/Alginates/PGA/Introduction/tabid/2409/fault/aspx.
22
Huajuan, L.; Koichi, A.; Inakuma, T.; Yamauchi, R. and Kato, K. (2005) Physical properties of water-
soluble pectins in hot and cold break tomato pastes. Food Chemistry, 93 (3), pg 403-408.
23
Paraskevopoulou, A.; Boskov, D. and Kiosseoglou, V. (2005) Stabilization of olive oil-lemon juice
emulsion with polysaccharides. Food Chemistry, 90 (4), pg 627-634.
24
Kailasapathy, K. and Sellepan, C.D. (1998) Effect of single and integrated emulsifier-stabilizer on
soy-ice confection. Food Chemistry, 63 (2), pg 181-186.
25
Milanovanovic, A.; Bozic, N. and Vujcic Z. (2007) Cell wall invertase immobilization within calcium
alginate beads. Food Chemistry, 104 (1), pg 81-86.
26
www.cargilltexturizing.com/products/hydrocolloids/alginates/cts_prod_hydro_alg_mol.shtml.
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alginates
27
. High-G alginates typically produce gels that are strong and exhibit good
heat stability. However, the gels are brittle and this can create a product with little
impact strength. Alginates containing large percentages of mannuronic acid content
are called high-M alginates. These alginates produce gels that are elastic, and this
increases freeze-thaw stability. The block sequences of glucuronic acid and

mannuronic acid monomer units also affect alginate functionality. Varying block
lengths such as GG, MG and MM produce gels with blended properties and regimes
of localized crystallization when glucuronic acid units are crosslinked with divalent
cations
28
. Figure 1.4-2 illustrates alginate glucuronic and mannuronic block types.

Guluronate block
Mannuronate block
Mannuronate-Guluronate-Mannuronate block
Guluronate block
Mannuronate block
Mannuronate-Guluronate-Mannuronate block









Figure 1.4-2: Alginate block types.
The divalent cation fits into the D-glucuronic acid block structure like eggs in an egg
box. This binds the alginate polymers together by forming junction zones which

27
Sime, Wilma J., (1990) Alginates Limewood, Raunds, Northhamptonshire NN9 6NG, UK p 53-60.
28
www.fmcbioploymer.com/food/ingredients/Alginates/PGA/Introduction/tabid/2410/fault/aspx.

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results in gelation
29
. Figure 1.4-3 illustrates the calcium binding site of D-glucuronate
and Figure 1.4-4 illustrates the egg box structure of calcium crosslinked alginate.




Guluronate GuluronateGuluronate Guluronate
Figure 1.4-3: Calcium binding site in polyguluronate dimer.




Figure 1.4-4: Calcium alginate cross- linked “Egg box” model.
2. Experimental Section
2.1 Experimental Objectives
The objectives of the present work are as follows:
a) Prepare uniform films of calcium alginate reproducibly in a 5 to 50μm

29
www.fmcbioploymer.com/food/ingredients/Alginates/PGA/Introduction/tabid/2412/fault/aspx.
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12
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thickness range.
b) Prepare uniform films of calcium pectinate reproducibly in a 5 to 50μm

thickness range.
c) Analytically measure the diffusion of benzaldehyde across the hydrogel
barriers to determine permeability and diffusion coefficients
2.2 Raw Materials
1. Sodium alginate extracted from brown seaweed (Phaeophyceae) was chosen
to create thin films. The sodium alginate is cross-linkable with divalent cations
such as Ca
2+
and Mg
2+
. The material is a whitish tan powder containing 1 to
3% moisture. The average molecular weight is 75,000 g/mol. The sodium
alginate trade name is Keltone LV and was supplied by ISP (International
Specialty Products) 1361 Alps Road, Wayne, New Jersey 07470.
2. Pectin extracted from lemon peel was chosen to create additional thin films.
The pectin is also cross-linkable with divalent cations such as Ca
2+
and Mg
2+
.
The material is a white powder containing approximately 3 to 4% moisture and
average molecular weight was 95,000 g/mol. The pectin trade name is TIC
Gum-32 and was supplied by TIC Gums, 4609 Richlynn Drive, Belcamp, MD
21017
3. Calcium chloride was used as the crosslinking material for sodium alginate
and pectin. The material is a white granular powder containing approximately
2% moisture. The calcium chloride was supplied by the Givaudan Flavor
Corporation, 1199 Edison Drive, Cincinnati, Ohio 45126. .
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4. Benzaldehyde was used to measure diffusion across the calcium alginate and
calcium pectin films. The benzaldehyde was 98% pure with a boiling point of
435.1 K. Benzaldehyde has a Log P value of 1.78 which is considered to be
relatively water soluble in the flavor industry. The benzaldehyde was supplied
by the Givaudan Flavor Corporation, 1199 Edison Drive, Cincinnati, Ohio
45126

O
Benzaldehyde

Figure 2.2-1: Structure of benzaldehyde.
5. Miglyol 812 (Medium chain triglycerides) was used to prepare dilute
benzaldehyde solutions. It is an oxidative-stable vegetable oil which was
supplied by Givaudan Flavor Corporation 1199 Edison Drive, Cincinnati, Ohio
45126.
2.3 Procedures – Laboratory Testing Equipment Preparation
2.3.1 Film Sheet Preparation
Three Baker’s Secret medium cookie sheets were purchased from a local grocery
store. The measurements of the cookie sheets were 43.2cm X 27.9cm X 1.9cm with
an estimated surface area of 1205.3 cm
2
. The cookie sheets were lightly scuffed
under water with an abrasive sponge to partially remove the Teflon™ coating from
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14
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