Starch Pickering Emulsions Process and Encapsulation Stability Marefati, Ali

208 Pages·2017·30.72 MB·English

Starch Pickering Emulsions
Process and Encapsulation Stability
Marefati, Ali
2018
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Marefati, A. (2018). Starch Pickering Emulsions: Process and Encapsulation Stability. [Doctoral Thesis
(compilation), Lund University]. Department of Food Technology, Lund University.
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LUND UNIVERSITY
PO Box 117
221 00 Lund
[phone]
Starch Pickering Emulsions
Process and Encapsulation Stability
DEPARTMENT OF FOOD TECHNOLOGY, ENGINEERING & NUTRITION | LUND UNIVERSITY
ALI MAREFATI

Starch Pickering Emulsions
Process and Encapsulation Stability

Ali Marefati

DOCTORAL DISSERTATION
by due permission of the Faculty of Engineering, Lund University, Sweden.
To be defended on Friday the 23rd March 2018, at 13:00, in Lecture Hall B at the
Centre for Chemistry and Chemical Engineering.

Faculty opponent
Professor Karin Schroën
Wageningen University, The Netherlands

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Organization: Document name:
LUND UNIVERSITY Doctoral Dissertation
Department of Food Technology, Date of issue: February the 27th, 2018
Engineering and Nutrition
P.O. Box 124, SE-22100 Lund,
Sweden
Author: Ali Marefati Sponsoring organization: Swedish Research Council
Title and subtitle:
Starch Pickering Emulsions: Process and Encapsulation Stability
Abstract
The emulsion stabilization functionality of surfactants and biopolymers can be replaced by solid
particles adsorbed at the interface, where they create a category of emulsions known as Pickering
emulsions. Recently, health and environmental concerns have led to new market demand for
natural, biodegradable and renewable sources of ingredients. Starch granules meet these
ingredient requirements and are also good candidates for stabilization of Pickering type emulsions
due to their properties such as neutral color, taste, odor and being non-allergic. Starch granules
are generally hydrophilic and in order to improve their emulsifying capacity they are modified with
hydrophobic groups. The most widely used chemical modification is esterification with acid
anhydride, such as octenyl succinic anhydride (OSA). Emulsions stabilized by OSA modified starch
have shown to have high stability. Moreover, the application of a heat treatment can induce a partial
gelatinization of the starch at the oil-water interface, which leads to changes in interfacial properties
of the starch granule stabilized emulsions.
This thesis focuses on the development and application of starch Pickering emulsions and has
been carried out along three main lines of investigation where each line has its own section in the
thesis. In the first section, the preparation and properties of oil-in-water emulsions stabilized by
starch granules with small sizes, including quinoa, rice and amaranth, were investigated. In the
second section, the process and encapsulation stabilities of the emulsions were evaluated in the
context of simple oil-in-water and double water-in-oil-in-water emulsions, with or without heat
treatment. In the third section, the physical and encapsulation stabilities of the emulsions during in
vitro digestion were evaluated.
Quinoa starch granules showed to have higher emulsifying efficiency both in the initial state and
after accelerated stability testing. Moreover, the heat induced gelatinized layer showed to not only
contribute to initial general stability, but also increased the process and encapsulation stabilities of
the emulsions. Modified starch granules appeared to protect the emulsions against destabilization
mechanisms during processing (i.e. freezing and freeze-drying). It was possible to create powders
from starch stabilized Pickering emulsions with high oil content (up to 80%). Furthermore,
emulsions stabilized by starch granules showed high stability for encapsulation of bioactive
compounds during in vitro digestion. The results of this work can be used for the development of
lipid-based encapsulated systems, in both liquid and powder forms for the delivery of bioactive
compounds in food, pharmaceutical and cosmetic applications.
Key words: Starch granules, Pickering emulsions, Encapsulation, Freeze-thaw stability, Freeze-
drying, In vitro digestion, in vitro intestinal lipolysis
Classification system and/or index terms (if any)
Supplementary bibliographical information Language: English
ISSN and key title ISBN (print): 978-91-7422-575-4
ISBN (digital): 978-91-7422-576-1
Recipient’s notes Number of pages:101 Price
Security classification
I, the undersigned, being the copyright owner of the abstract of the above-mentioned dissertation, hereby
grant to all reference sources permission to publish and disseminate the abstract of the above-mentioned
dissertation.
Signature Date: February the 14th, 2018
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Starch Pickering Emulsions
Process and Encapsulation Stability

Ali Marefati

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Cover photo by Hisyalina Saari
Back cover by Stephen Hall

Copyright Ali Marefati

Faculty of Engineering, Lund University
Department of Food Technology, Engineering and Nutrition

ISBN (print) 978-91-7422-575-4
ISSN (digital) 978-91-7422-576-1

Printed in Sweden by Media-Tryck, Lund University
Lund 2018

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Two roads diverged in a wood, and I–
I took the one less traveled by,
And that has made all the difference.

Robert Frost (1874-1963)

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Contents

Abstract .................................................................................................................... 1
Popular science summary ......................................................................................... 3
List of publications ................................................................................................... 6
Additional publication not included in this thesis .................................................... 7
Author’s contribution to the publications ................................................................. 8
Contribution to conferences and workshops ............................................................ 9
Aim and objectives ................................................................................................. 11
Introduction ............................................................................................................ 12
Overview of design of the thesis work ......................................................... 13
Background ............................................................................................................ 14
Emulsions ..................................................................................................... 14
Multiple emulsions ....................................................................................... 15
Instability mechanisms ................................................................................. 16
Emulsion characteristics ............................................................................... 18
Pickering Emulsions ..................................................................................... 21
Starch............................................................................................................ 25
Size, shape and morphology of starch granules .................................. 25
Small granular starches ........................................................................ 25
Structure of starch granules ................................................................. 27
Bioavailability/digestibility ................................................................. 29
Gelatinization ...................................................................................... 29
Retrogradation ..................................................................................... 31
Modified starch ............................................................................................ 32
Starch as emulsion stabilizer ........................................................................ 33
Molecular starch .................................................................................. 33
Starch particles .................................................................................... 33
Functionality and application of Pickering emulsions ................................. 34
Process stability ................................................................................... 34
Encapsulation ...................................................................................... 35
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Lipolysis inhibition .............................................................................. 37
General Methods .................................................................................................... 39
Isolation, modification and characterization of starch granules ................... 39
Isolation of starch ................................................................................ 39
OSA modification ................................................................................ 40
Characterization of starch granules ..................................................... 41
Emulsification and characterization of emulsions ........................................ 42
Emulsification ..................................................................................... 42
Accelerated stability test ...................................................................... 43
Application of heat treatment .............................................................. 43
Emulsions droplet size characterization .............................................. 44
Assessment of functional properties of starch Pickering emulsions ............ 45
Process stability ................................................................................... 45
Encapsulation stability ......................................................................... 46
Physiological stability ......................................................................... 47
Summary of the main results .................................................................................. 51
Section I (papers I and II) ............................................................................. 51
Section II (papers III and IV) ....................................................................... 58
Section III (papers V and VI) ....................................................................... 64
Conclusions ............................................................................................................ 74
Section I (papers I and II) ............................................................................. 74
Section II (papers III and IV) ....................................................................... 75
Section II (papers V and VI) ........................................................................ 75
Future perspectives ................................................................................................. 77
Acknowledgements ................................................................................................ 79
References .............................................................................................................. 81

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