Strategies to Improve the Performance of Antioxidants in Oil-in-Water Emulsions

187 Pages·2014·1.76 MB·English

by  Atikorn Panya

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Open Access Dissertations
9-2012
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Atikorn Panya
University of Massachusetts Amherst
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Panya, Atikorn, "Strategies to Improve the Performance of Antioxidants in Oil-in-Water Emulsions" (2012).
Open Access Dissertations. 655.
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STRATEGIES TO IMPROVE THE PERFORMANCE OF ANTIOXIDANTS IN
OIL-IN-WATER EMULSIONS

A Dissertation Presented

by

ATIKORN PANYA

Submitted to the Graduate School of the
University of Massachusetts Amherst in partial fulfillment
of the requirements for the degree of

DOCTOR OF PHILOSOPHY

September 2012

The Department of Food Science

i
© Copyright by Atikorn Panya 2012
All Rights Reserved
ii
STRATEGIES TO IMPROVE THE PERFORMANCE OF ANTIOXIDANTS IN
OIL-IN-WATER EMULSIONS

A Dissertation Presented
by
ATIKORN PANYA

Approved as to style and content by:

__________________________________________
Eric A. Decker, Chair

__________________________________________
D. Julian McClements, Member

__________________________________________
Paul M. Lahti, Member

________________________________________
Eric A. Decker, Department Head
Department of Food Science
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DEDICATIONS

To my mom and dad, and all my friends, and my destiny in science

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ACKNOWLEDGMENTS

I would like to express my thanks to my advisor, Dr. Eric A. Decker, for accepting
me as his Ph.D. student, offering me the great opportunity to conduct this remarkable
research topic, and supporting me with his kind guidance, intelligence and strong
experiences. I would like to thank Dr. Julian McClements for his kind suggestion on this
research and his enthusiasm to come up with new research ideas. I would like to thank
Dr. Micha Peleg and Dr. Mark Normand for their suggestion and hard effort to help me
developing a simulation mathematical model that I can use in my future research.
Also, I would like to extend special thanks to Dr. Paul M. Lahti in the chemistry
department, Umass Amherst for being a member of my committee. I appreciated for his
donating valuable times to teach and suggest me on developing EPR techniques used in
this research.
I would like to express my appreciation to Jean Alamed for her continuous
assistance in my research as well as her friendship. Many thanks to Bingcan, Get, Dao
and Mickaël for their continuing and unconditional friendship and support over the years;
I could not have done this without their helps. I would also like to thank all faculty, staff
and lab members with special thanks to Dr. Xiao, Fran and Dan. In addition, I would like
to thank all my Thai friends in Umass Amherst. I’ve never been missing my hometown.
I would like to thank all staffs in the Royal Thai government and office of
educational affairs in Thailand and USA for the scholarship and support during my Ph.D.
study.

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ABSTRACT

STRATEGIES TO IMPROVE THE PERFORMANCE OF ANTIOXIDANTS IN OIL-
IN-WATER EMULSIONS
SEPTEMBER 2012
ATIKORN PANYA, B.S., KHONKAEN UNIVERSITY, KHONKAEN, THAILAND
M.S., MAHIDOL UNIVERSTY, BANGKOK, THAILAND
Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST MA
Directed by: Professor Eric A. Decker

Due to the limited number of approved antioxidants for food applications, several
alternative strategies to improve antioxidant performance have been developed by
focusing on synergistic antioxidant interactions. Susceptibility to lipid oxidation in food
systems is the result of the summation of antioxidative and prooxidative mechanisms.
Understanding the sometimes paradoxical behavior of antioxidants and prooxidants is a
vital key to design synergistic antioxidant systems suitable for particular foods. This
research focused on 3 main strategies to improve the performance of antioxidant activity
in oil-in-water emulsions.
The first part of this research has been focused on inhibition of lipid oxidation by
a combination of the modification of liposomal surfaces by chitosan-coating techniques
along with addition of rosmarinic acid esters of varying polarity. Repelling metal ions
away from the interface of positively charged liposomes can inhibit lipid oxidation
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(induced by Fe2+), and also reduce antioxidant loss by Fe3+ reduction. As a result, lipid
oxidation can be inhibited synergistically because of a reduction in the prooxidant
activity of iron.
Second, understanding non-linear antioxidant behavior (the cut-off effect) of
antioxidant esters in oil-in-water (O/W) emulsions was also studied to determine how the
distributions and locations of antioxidants impacted their antioxidant activity.
Antioxidant activity of rosmarinic acid was improved by esterification with alkyl chain
lengths between 4 to 12 carbons due to increased ability to partitioning at the interface in
oil-in-water emulsions. Surfactant micelles which could increase or decreased the
concentration of the antioxidants at the emulsion droplet interface altered antioxidant
activity.
In the last part of this research, rosmarinic acid and its esters were found to be an
excellent tool for studying how antioxidant location could impact its ability to interact
with α-tocopherol in O/W emulsions. Synergistic, additive, and antagonistic effects were
observed in the combinations between the rosmarinate esters with α-tocopherol. Increases
in alkyl chain lengths of rosmarinic acid have influenced both the partitioning of the
rosmarinate esters as well as their ability to they interact with α-tocopherol at the
interface of oil-in-water emulsions. Fluorescence quenching and EPR studies showed that
water soluble rosmarinic acid (R0) exhibited more interactions with α-tocopherol than
any of the esters (R4-R20). Synergistic antioxidant interactions between rosmarinic acid
and α-tocopherol could not be explained by electron transfer mechanisms, but formation
of caffeic acid from rosmarinic acid. Due to the thermodynamic infeasibility and the fact
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that increases in α-tocopherol degradation rates, α-tocopherol could not be regenerated
efficiently by rosmarinic acid. This formation of caffeic acid was proposed to be
responsible of the synergistic activity of R0 and α-tocopherol since the formation of an
additional antioxidant could further increase the oxidative stability of the emulsion.

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TABLE OF CONTENTS

Page

ACKNOWLEDGMENTS ...................................................................................................v

ABSTRACT ....................................................................................................................... vi

LIST OF TABLES .............................................................................................................xv

LIST OF FIGURES ......................................................................................................... xvi

CHAPTER

1. INTRODUCTION ...................................................................................................1

2. LITERATURE REVIEW ........................................................................................4

2.1 Principles of lipid oxidation mechanisms ..........................................................4

2.2 Beyond the polar paradox theory .......................................................................6

2.3 Principles of synergistic antioxidant interactions ............................................10

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