Starch-Pectin Matrices for Encapsulation of Ascorbic Acid

101 Pages·2014·0.91 MB·English

by  Yiwei Liu

University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Dissertations, Theses, & Student Research in Food
Food Science and Technology Department
Science and Technology
5-2014
Starch-Pectin Matrices for Encapsulation of
Ascorbic Acid
Yiwei Liu
University of Nebraska-Lincoln, [email protected]
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STARCH-PECTIN MATRICES FOR ENCAPSULATION OF ASCORBIC ACID

by

Yiwei Liu

A THESIS

Presented to the Faculty of
The Graduate College at the University of Nebraska
In Partial Fulfillment of Requirements
For the Degree of Master of Science

Major: Food Science and Technology

Under the Supervision of Professor Wajira S. Ratnayake

Lincoln, Nebraska

May, 2014
STARCH-PECTIN MATRICES FOR ENCAPSULATION OF ASCORBIC ACID
Yiwei Liu, M.S.
University of Nebraska, 2014
Advisor: Wajira S. Ratnayake
Starch and pectin are two food-grade carbohydrates widely utilized in the food
industry. Starch and pectin polymers have been investigated in encapsulating functional
food ingredients and in pharmaceutical applications. Resistance to enzyme hydrolysis,
differential solubilities, depending on the pH, and the ability to ‘protect’ unstable
molecules are considered some of the beneficial properties of starch and pectin polymers,
for encapsulation applications. Food ingredients could be delivered in a controlled
manner to a specific target by encapsulating in micro-scale particles, i. e.,
microencapsulation. Two studies were conducted to investigate the ability of selected
starch-pectin blends in microencapsulating ascorbic acid (vitamin C) by spray-drying.
The first study investigated the properties of heat-treated resistant starch and pectin based
microparticles; blends of 50% amylose and 70% amylose, and type 4 resistant (RS 4)
starches, were used with high methoxyl pectin at selected ratios. The second study
investigated the properties of gelatinized regular starch and pectin based microparticles
that were prepared by spray drying with a three-fluid nozzle, in encapsulating ascorbic
acid. The type of starch, as well as starch-pectin ratio influenced both physical and
functional properties of the microparticles.
iii

ACKNOWLEDGEMENTS

I wish to thank Dr. Wajira Ratnayake, my Major Advisor, for his support,
guidance, and patience throughout the course of my graduate program. My thanks are
also extended to my graduate committee members, Dr. Rolando Flores, Dr. Randy
Wehling, and Dr. Milford Hanna, for their support and advice on my research and study.
Sincere thanks are also extended to my colleagues, Hui (Mary) Wang, Lucia
Miceli-Garcia, Liya Mo, and Shreya Sahasrabudhe, for their collaboration and help in the
laboratory, stimulating discussions, friendship, and support.
I would like to thank Dr. Han Chen of the Morrison Microscopy Core Research
Facility, for the valuable assistance in electron microscopy.
I gratefully appreciate the love and care from my family and friends throughout
my studies at University of Nebraska-Lincoln.

Yiwei Liu
April 23, 2014

Lincoln, NE
iv

TABLE OF CONTENTS

ACKNOWLEDGEMENTS iii
LIST OF TABLES viii
LIST OF FIGURES ix
ABBREVIATIONS x
INTRODUCTION 1
OBJECTIVES AND HYPOTHESES 6
CHAPTER 1. LITERATURE REVIEW 7
1.1 Microencapsulation 7
1.2 Microencapsulation technique 8
1.2.1 Spray drying 8
1.3 Wall material selection 9
1.3.1 Starch 10
1.3.2 Pectin 13
1.4 Release mechanism 14
1.5 Ascorbic acid 15
1.6 Physicochemical characterization of microparticles 16
1.6.1 Particle size distribution 17
1.6.2 Morphology of microparticles 17
1.6.3 Encapsulation efficiency 18
1.6.4 In vitro release profiles 19
1.7 Conclusions 19
v

References 21
CHAPTER 2. ENCAPSULATION OF ASCORBIC ACID IN HEAT TREATED
RESISTANT STARCH-PECTIN BASED MICROPARTICLES 36
Abstract 36
2.1 Introduction 36
2.2 Materials and methods 39
2.2.1 Materials 39
2.2.2 Thermal properties of raw starches 39
2.2.3 Swelling factor of raw starches 40
2.2.4 Preparation of microparticles 40
2.2.4.1 Preparation of feed solutions 40
2.2.4.2 Spray drying with two-fluid nozzle 41
2.2.5 Analysis of physical properties of microparticles 41
2.2.5.1 Particle size distribution 41
2.2.5.2 Surface morphology 42
2.2.6 Evaluation of functional properties of microparticles 42
2.2.6.1 Encapsulation efficiency 42
2.2.6.2 In vitro release profiles 43
2.2.7 Statistical analysis 44
2.3 Results and discussion 44
2.3.1 Properties of raw starches 44
2.3.1.1 Thermal properties 44
2.3.1.2 Swelling factor 45
vi

2.3.2 Physical properties of microparticles 46
2.3.2.1 Particle size distributions 46
2.3.2.2 Surface morphology 47
2.3.3 Functional properties of microparticles 48
2.3.3.1 Encapsulation efficiency 48
2.3.3.2 In vitro release profiles 48
2.4 Conclusions 50
References 51
CHAPTER 3. ENCAPSULATION OF ASCORBIC ACID IN GELATINIZED
STARCH-PECIN MICROPARTICLES BY SPRAY DRYING WITH THREE-FLUID
NOZZLE 68
Abstract 68
3.1 Introduction 68
3.2 Materials and methods 70
3.2.1 Materials 70
3.2.2 Preparation of microparticles 70
3.2.2.1 Preparation of feed solutions 70
3.2.2.2 Spray drying with three-fluid nozzle 71
3.2.3 Analysis of physical properties 71
3.2.3.1 Particle size analysis 71
3.2.3.2 Surface morphology 72
3.2.4 Analysis of functional properties 72
3.2.4.1 Encapsulation efficiency 72
vii

3.2.4.2 In vitro release profiles 73
3.2.5 Statistical analysis 74
3.3 Results and discussion 74
3.3.1 Physical properties of microparticles 74
3.3.1.1 Particle size distributions 74
3.3.1.2 Surface morphology 75
3.3.2 Functional properties of microparticles 75
3.3.2.1 Encapsulation efficiency 75
3.3.2.2 In vitro release profiles 76
3.4 Conclusions 77
References 78
OVERALL SUMMARY 89
viii

LIST OF TABLES

Table 1.1. Comparison of microencapsulation techniques. 35
Table 2.1. Starch & pectin compositions of wall material formulations. 62
Table 2.2. DSC phase transition parameters of starches used for encapsulation. 63
Table 2.3. Swelling factors of raw starches. 64
Table 2.4. Size distributions of microparticles. 65
Table 2.5. Encapsulation efficiencies of microparticles. 66
Table 2.6. Cumulative ascorbic acid released by microparticles after 7 hours. 67
Table 3.1. Size distributions of microparticles. 86
Table 3.2. Encapsulation efficiencies of microparticles. 87
Table 3.3. Total ascorbic acid released by microparticles after 7 hours at selected pH
levels. 88
ix

LIST OF FIGURES

Figure 2.1. Size distribution profiles of microparticles. 59
Figure 2.2. SEM images of microparticles (3000x). 60
Figure 2.3. Release profiles of ascorbic acid at selected pH levels. 61
Figure 3.1. Preparation of microparticles. 82
Figure 3.2. Size distribution profiles of microparticles. 83
Figure 3.3. SEM images of microparticles (3000x). 84
Figure 3.4. Release profiles of ascorbic acid at selected pH levels. 85