encapsulation and release of amino acids in double

63 Pages·2017·1.7 MB·English

by  Ricardo Uribe

ENCAPSULATION AND RELEASE
OF AMINO ACIDS IN DOUBLE
(W/O/W) EMULSION

Ricardo Uribe Alvarez
Student number: 01508487

Promotor: Prof. dr. ir. Paul Van der Meeren
Tutor: ir. Mathieu Balcaen

Master’s Dissertation submitted to Ghent University in partial fulfilment of the requirements for the
degree of Master of Science in Food Technology

Academic Year: 2016 - 2017

The author and the promoters give the permission to consult and copy parts of this work for personal

use only. Any other use is under the limitations of copyrights laws, more specifically it is obligatory
to specify the source when using results from this thesis.

Gent, August 2017

The promotor The author
Prof. dr ir. Paul Van der Meeren Ricardo Uribe Alvarez

Acknowledgments
I would like to thank my promoter, Prof. dr. ir. Paul Van der Meeren, for his support and knowledge
throughout this research. Also, my sincere thanks to my tutor, Mathieu Balcaen, for his continuous
guidance, support and advice through the learning process of this master thesis. And deep gratitude
to the members of the department of Applied Analytical and Physical Chemistry for their help and
support.
I would also like to thank the National Council on Science and Technology of Mexico and the State
Council on Science and Technology of Jalisco (CONACYT and COECYTJAL, according to its
Spanish abbreviation) for providing me the necessary means to focus on my studies throughout these
two years. And I extend my gratitude to Ghent University and KU Leuven for giving me the
opportunity to pursue my master’s degree.
Finally, I must express my very profound gratitude to my parents, my sister and friends for providing
me with unfailing support and continuous encouragement throughout my years of study and through
the process of researching and writing this thesis.

Table of contents

Abstract 1

Chapter 1 Literature review
1.1 Colloidal systems 2
1.2 Emulsions 3
1.3 Double emulsions 3
1.3.1 Preparation 4
1.3.2 Instability 6
1.3.3 Release of entrapped compounds 7
1.3.4 Potential uses 9
1.4 Amino acids 10
1.4.1 Hydrophobicity 11
1.4.2 Chemical reactivity 12
1.4.3 Quantification 13
1.4.4 Encapsulation 13

Chapter 2 Materials and methods
2.1 Materials 14
2.2 Absorbance spectrum analysis 14
2.3 Composition of the water-in-oil-in-water (W /O/W ) emulsions 15
1 2
2.3.1 W /O/W emulsions with low amino acid concentration 15
1 2
2.3.2 W /O/W emulsions with high amino acid concentration 15
1 2
2.3.3 W /O/W emulsions with varying hydrophilic surfactant concentration 16
1 2
2.4 Preparation of W /O/W emulsion 16
1 2
2.4.1 Water in oil (W /O) emulsions preparation 16
1
2.4.2 W /O/W emulsions preparation 16
1 2
2.5 Characterization of W /O/W emulsions 16
1 2
2.5.1 Determination of average droplet size 16
2.5.2 Water yield determination 17
2.5.3 Microscopy 18
2.6 Determination of released amino acid 18
2.6.1 Collection of the external phase 18
2.6.2 Reaction with TNBS 18
2.6.3 Method of determination 18
2.6.3.1 Standard curve determination 18
2.6.3.2 Determination considering turbidity effect 19
2.7 Model of released amount of amino acids 20
2.8 Statistical analysis 20

Chapter 3 Results and discussion
3.1 Method development for the determination of amino acids in the external phase
of W /O/W emulsions 21
1 2
3.1.1 Absorbance spectrum test of L-leucine in external phase 21
3.1.2 Amino acid quantification tests 23
3.1.2.1 Test with low amino acid concentration in the internal phase 23
3.1.2.2 Test with high amino acid concentration in the internal phase 25
3.1.2.2.1 Standard curve method 25
3.1.2.2.2 Method considering turbidity effect 26
3.1.2.2.3 Differences between determination methods 31
3.2 Encapsulation efficiency of amino acids in double emulsions 32
3.2.1 Release as function of amino acid properties 32
3.2.1.1 Double emulsion droplet size 32
3.2.1.2 Yield of entrapped water 34
3.2.1.3 Standard curves 35
3.2.1.4 Amino acids release profiles 36
3.2.1.5 Influence of the type of amino acid 38
3.2.2 Release as function of the high HLB emulsifier concentration 41
3.2.2.1 Double emulsion droplet size 41
3.2.2.2 Yield of entrapped water 42
3.2.2.3 Standard curve 43
3.2.2.4 Polysorbate 80 concentration influence in the release of L-leucine 43
3.2.3 Microscopy 45

General Conclusions 47

References 49