Encapsulation of Folic Acid in Sodium Alginate-Pectin-Poly(Ethylene Oxide)

172 Pages·2012·2 MB·English

Encapsulation of Folic Acid in Sodium Alginate-Pectin-Poly(Ethylene
Oxide) Electrospun Fibers to Increase Its Stability

by

Solmaz Alborzi

A Thesis
Presented to
The University of Guelph

In partial fulfillment of requirements
for the degree of
Doctor of Philosophy
in
Food Science

Guelph, Ontario, Canada

© Solmaz Alborzi, August, 2012
ABSTRACT

ENCAPSULATION OF FOLIC ACID IN SODIUM ALGINATE-PECTIN-
POLY(ETHYLENE OXIDE) ELECTROSPUN FIBERS TO INCREASE
ITS STABILITY

Solmaz Alborzi Advisor:
University of Guelph, 2012 Professor L-T. Lim

This thesis explored the use of sodium alginate-pectin-poly(ethylene oxide)
electrospun fibers as a carrier to stabilize folic acid - an essential micronutrient that is
susceptible to degradation when exposed to light and acidic conditions. In the first phase
of this research, electrospinning behaviour of aqueous alginate-pectin solutions was
investigated. Aqueous polysaccharide solutions could not be electrospun unless
poly(ethylene oxide) (PEO) was added (≥20% w/w), resulting in electrospun
alginate-pectin fibers that varied from fiber to fiber-bead, depending on the polymer
blend ratio, and concentration of the polymer solutions. Polymer solutions properties
(surface tension, viscosity, conductivity) were determined to study their effects on the
electrospinning behaviour of the polymer solutions. In the second phase of this research,
folic acid was incorporated into the polymer solutions and electrospun. The efficacy of
these fibers in improving the stability of folic acid under different pH conditions was
investigated. FTIR and NMR spectroscopies were employed to elucidate the nature of
polymer-polymer and folic acid-polymer interaction. In phase three, the release behaviour
of folic acid under simulated gastrointestinal conditions was evaluated.
Overall, this research showed that electrospun fibers with different morphologies
could be produced by manipulating the polymer concentration, polysaccharide/PEO
blend ratio, extent of sonication treatment during sample preparation, and electrospinning
process parameters. The positive effect of PEO on the electrospining of alginate-pectin
fibers was attributed to its electrical conductivity and surface tension lowering effects on
the polymer solutions. Electrospun fibers produced from the combination of alginate-
pectin resulted in higher retention of folic acid compared to that of alginate alone. Folic
acid encapsulated in crosslinked electrospun fibers achieved close to 100% retention
when stored in the dark at pH 3 after 41 days of storage. Minimal release of folic acid
from the electrospun fibers was observed at pH 3, although the release was significantly
higher at pH 1.2. On the other hand, the release of folic acid was nearly 97% at pH 7.8, a
condition that simulated the pH condition in the intestine. From NMR and FTIR data, the
stabilization effect of electrospun fibers on folic acid was attributed to physical
entrapment and not specific chemical interaction.
The research suggests that ethanol-treated crosslinked alginate-pectin electrospun
fibers can potentially be used as a folic acid carrier to protect the micronutrient in food
products, especially acidic food products such as fruit juices and acidified beverages.
Acknowledgements
I would like to begin by expressing my deep gratitude to my advisor,
Dr. Loong-Tak Lim, for being my mentor as I pursued my Ph.D., for the encouragement
and confidence he gave me at challenging milestones in my project, and for the patience
and guidance he extended to me throughout this process.
I would also like to acknowledge the support of my advisory committee members
- Dr. Yukio Kakuda, for devoting time to helping me in so many aspects of my research
project; Dr. Amanda Wright, for the advice she gave me and for permitting me to work in
her laboratory; Dr. Koushik Seetharaman, for his ongoing support and encouragement;
and Dr. Shesha Jayaram, for the advice and support she gave me during my research.
Special thanks also go to Dr. Ronald J. Neufeld, for being my external examiner. I would
also like to convey my special thanks to all my examination committee members - Dr.
Massimo Marcone, Dr. Keith Warriner, and Dr. Yukio Kakuda for their valuable time
and support. I would also like to thank the staff in the Department of Food Science and
Dr. Sandy Smith for her friendly support during my SEM analyses. I will always be
extremely grateful to Dr. Keith Warriner for encouraging me to enter the Ph.D. program.
To my lab mates in the packaging and biomaterial group, I extend heartfelt thanks for
their friendship and support during challenging times. I would also like to thank the
Natural Sciences and Engineering Research Council of Canada (NSERC) and Heinz
Company of Canada for their financial support of this project.
I would like to thank my parents, Abdolvahab Alborzi, and Nahid Bahmani
Bahmanbigloo, for the love and support they have given me all my life and for
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encouraging me to work hard and have the confidence to pursue my dreams. Many, many
thanks go also to my sister, Pooneh and her husband Matthew, and to my brother
Behrang and his wife Niloofar, for providing a loving environment that always helped me
through challenging times.
Finally, my deepest gratitude and love go to my husband, Mahmood Rashidi, for
believing in me and for patiently helping me cope with the stress of work and with
technical aspects of my research.

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This thesis is dedicated to my husband, Mahmood Rashidi, to my parents, Abdolvahab
Alborzi and Nahid Bahmani Bahmanbigloo, and to my nephew, Bijan Ryan Foroughi, for
their love, endless support, and encouragement.

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Table of Contents
Acknowledgements ............................................................................................................ iv
Table of Contents .............................................................................................................. vii
List of Tables .................................................................................................................... xii
List of Figures .................................................................................................................. xiii
List of Abbreviation ........................................................................................................ xvii
CHAPTER 1: LITERATURE REVIEW ............................................................................ 1
1.1 Vitamins ........................................................................................................................ 1
1.2 Folate ............................................................................................................................ 2
1.2.1 Folate Stability .................................................................................................... 4
1.3 Deficiency of folic acid ................................................................................................. 6
1.3.1 Folic acid deficiency and neural tube defects (NTDs) ....................................... 6
1.3.2 Folic acid deficiency and heart disease .............................................................. 8
1.3.3 Folic acid deficiency and cancer risk ................................................................. 9
1.3.4 Folic acid deficiency and Alzheimer’s disease ................................................... 9
1.4 Sources of Folate ........................................................................................................ 10
1.5 Methods of folic acid fortification in foods ................................................................ 11
1.5.1 Direct addition of unencapsulated free folic acid ............................................. 11
1.5.2 Addition of encapsulated folic acid .................................................................. 11
1.6 Microencapsulation ..................................................................................................... 12
1.6.1 Different microencapsulation techniques ......................................................... 13
1.6.1.1 Spray drying ............................................................................................... 13
1.6.1.2 Spray cooling ............................................................................................. 14
1.6.1.3 Extrusion .................................................................................................... 15
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1.6.1.4 Fluidized bed coating ................................................................................. 16
1.6.1.5 Liposome.................................................................................................... 16
1.6.1.6 Coacervation .............................................................................................. 17
1.7 Nanofibers ................................................................................................................... 18
1.8 Techniques for producing nanofibers ......................................................................... 20
1.8.1 Drawing ............................................................................................................ 20
1.8.2 Template synthesis ........................................................................................... 21
1.8.3 Phase separation ............................................................................................... 21
1.8.4 Self assembly .................................................................................................... 22
1.8.5 Electrospinning ................................................................................................. 22
1.9 Factors affecting electrospinning process ................................................................... 24
1.9.1 Polymer solution parameters ............................................................................ 25
1.9.2 Processing Parameters ...................................................................................... 27
1.10 Polymers for electrospinning .................................................................................... 28
1.10.1 Sodium alginate .............................................................................................. 29
1.10.1.1 Sources and extraction ............................................................................. 29
1.10.1.2 Structure of alginate ................................................................................. 29
1.10.1.3 Gel formation ........................................................................................... 31
1.10.1.4 Applications of alginate ........................................................................... 32
1.10.2 Pectin .............................................................................................................. 34
1.10.2.1 Sources and extraction ............................................................................. 34
1.10.2.2. Pectin Structure ....................................................................................... 34
1.10.2.3 Property of pectin ..................................................................................... 35
1.10.2.4 Applications of pectin .............................................................................. 36
1.10.3 Alginate-pectin systems .................................................................................. 37
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CHAPTER 2: RESEARCH OBJECTIVES ...................................................................... 39
2.1 Background ................................................................................................................. 39
2.2 Overall objective ......................................................................................................... 43
2.3 Research Hypotheses ................................................................................................. 43
CHAPTER 3: ELECTROSPINNING OF SODIUM ALGINATE-PECTIN ULTRAFINE
FIBERS ............................................................................................................................. 44
3.1. Introduction ................................................................................................................ 45
3.2 Materials and Methods ................................................................................................ 47
3.2.1 Materials ........................................................................................................... 47
3.2.2 Methods ............................................................................................................ 47
3.2.2.1 Preparation of polymer solution................................................................. 47
3.2.2.2 Electrospinning of nanofibers .................................................................... 48
3.2.2.3 Scanning electron microscopy analysis ..................................................... 49
3.2.2.4 Viscosity measurement .............................................................................. 50
3.2.2.5 Conductivity measurement ........................................................................ 51
3.2.2.6 Dialysis of alginate-pectin polymer solution ............................................. 51
3.2.2.7 Surface tension measurement .................................................................... 52
3.2.2.8 Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR)
evaluation ............................................................................................................... 53
3.2.2.9 Nucleic magnetic resonance (NMR) evaluation ........................................ 53
3.3 Results and Discussion ............................................................................................... 54
3.3.1 PEO and concentration effects on fiber morphology ....................................... 54
3.3.2 PEO and concentration effects on polymer solution properties ....................... 58
3.3.3 Sodium alginate-type effect on fiber morphologies ......................................... 73
3.3.4 Ultrasonic mixing effects on fiber morphologies ............................................. 73
3.3.5 FTIR and NMR analyses on alginate-pectin electrospun fibers ....................... 77
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3.4 Conclusions ................................................................................................................. 82
CHAPTER 4: ENCAPSULATION OF FOLIC ACID AND ITS STABILTY IN
SODIUM ALGINATE-PECTIN-POLY(ETHYLENE OXIDE) ELECTROSPUN
FIBERS ............................................................................................................................. 83
4.1 Introduction ................................................................................................................. 84
4.2 Materials and methods ................................................................................................ 88
4.2.1 Materials ........................................................................................................... 88
4.2.2 Methods ............................................................................................................ 89
4.2.2.1 Preparation of electrospinning solution ..................................................... 89
4.2.2.2 Electrospinning of Nanofibers ................................................................... 90
4.2.2.4 Stability of encapsulated folic acid under accelerated storage condition .. 92
4.2.2.5 Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR)
evaluation ............................................................................................................... 94
4.2.2.6 Nucleic magnetic resonance (NMR) evaluation ........................................ 94
4.2.2.7 Scanning electron microscopy (SEM) analysis ......................................... 95
4.3 Results and Discussion ............................................................................................... 95
4.3.1 Results of preliminary stability test .................................................................. 95
4.3.2 Stability of folic acid encapsulated in 3% MSAP/PEO (70/30) and 5%
LSAP/PEO (70/30) .................................................................................................... 98
4.3.3 Effect of pectin on the stability of folic acid .................................................. 105
4.3.4 FTIR and NMR analyses on alginate-pectin electrospun fibers ..................... 106
4.4 Conclusions ............................................................................................................... 111
CHAPTER 5: IVESTIGATION OF THE IN VITRO RELEASE BEHAVIOR OF FOLIC
ACID FROM SODIUM-ALGINATE-PECTIN-POLY(ETHYLENE OXIDE)
ELECTROSPUN FIBERS .............................................................................................. 112
5.1 Introduction ............................................................................................................... 113
5.2 Materials and Methods .............................................................................................. 116
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