L AB OR AT ORY
of
F OOD
CHE MI S TRY
Information on
BSc and MSc thesis projects
at the Laboratory of Food Chemistry
Last update 2/3/2017
Go to www.fch.wur.nl ( education)
BSc and MSc thesis projects – Laboratory of Food Chemistry
Table of Contents
CHOOSING AND PERFORMING A THESIS RESEARCH PROJECT AT THE LABORATORY OF FOOD CHEMISTRY ..... 2
PART 1: QUALITY AND/OR PROCESSING OF FOOD (RAW) MATERIALS ............................................................. 4
EFFECT OF THE MAILLARD REACTION ON PROTEIN DIGESTIBILITY (DAIRY SUBJECT) ................................................................. 4
THE ROLE OF MAILLARD REACTIONS IN PROTEIN FOAM STABILITY (DAIRY SUBJECT) ............................................................... 4
INGREDIENTS, INTERFACES AND ICE CREAM (DAIRY SUBJECT) ............................................................................................ 5
FREE RADICAL INTERMEDIATES PRODUCED DURING PRIMARY LIPID OXIDATION IN O/W FOOD EMULSIONS ................................. 6
NEW ANALYTICAL TECHNIQUES FOR RESEARCH ON FOOD.................................................................................................. 6
PART 2: ENZYMATIC OR FUNGAL UPGRADING OF FOOD (RAW) MATERIALS .................................................... 7
UPGRADING LIGNIN – FUTURE AS NATURAL INGREDIENT FOR FOOD & FEED OR NATURAL CHEMICALS? ...................................... 7
CAN LACCASE-MEDIATOR SYSTEMS UPGRADE LIGNIN: NEW NATURAL INGREDIENTS? ............................................................. 8
PART 3: HEALTH ASPECTS OF FOOD ................................................................................................................. 9
ENHANCING THE PRODUCTION OF PLANT METABOLITES WITH ANTIMICROBIAL ACTIVITY ......................................................... 9
STRUCTURE ACTIVITY RELATIONSHIPS OF ISOFLAVONOIDS AS ANTIMICROBIAL AGENTS .......................................................... 10
ANTIMICROBIAL PHYTOCHEMICALS FROM BRASSICA ..................................................................................................... 11
EFFECTS OF PROCESSING OF PROTEINS ON THEIR IMMUNOGENICITY: ALLERGY AS A MODEL (DAIRY SUBJECT) ............................ 12
THE FATE OF HUMAN MILK OLIGOSACCHARIDES (HMO) IN INFANT GUT (DAIRY SUBJECT) .................................................. 13
N-GLYCANS IN BOVINE AND HUMAN MILK (DAIRY SUBJECT) ........................................................................................... 13
TOWARD CONTROLLED STEERING OF MICROBIOTA AND IMMUNITY IN INFANTS BY NON-DIGESTIBLE CARBOHYDRATES ................. 14
BEHAVIOUR AND DIGESTIBILITY OF STARCH IN PIGS ....................................................................................................... 15
CARBS CAN MAKE THE DIFFERENCE: HOW PECTINS FUEL IMMUNITY .................................................................................. 16
THE EFFECT OF PROTEIN STRUCTURE ON DIGESTION DYNAMICS (DAIRY SUBJECT) ................................................................. 17
THE EFFECT OF DAIRY PROTEIN COMPOSITION ON PROTEIN DIGESTION KINETICS.................................................................. 18
PART 4: NEW AND/OR IMPROVED INGREDIENTS FOR FOOD.......................................................................... 19
USE OF ENZYMATIC CROSSLINKING TO PRODUCE PROTEIN NANOPARTICLES (DAIRY SUBJECT) ................................................. 19
UNDERSTANDING POLYSACCHARIDE INTERACTIONS IN FRUITS AND VEGETABLES .................................................................. 20
ISOMALTO/MALTO-POLYSACCHARIDES (IMMPS): NOVEL POLYSACCHARIDES FROM STARCH. .............................................. 21
PART 5: EDUCATIONAL DEVELOPMENT .......................................................................................................... 22
DESIGN AND/OR EVALUATION OF DIGITAL LEARNING MATERIAL FOR FOOD CHEMISTRY ........................................................ 22
DEVELOPING NEW LEARNING ACTIVITIES OR IMPROVING EXISTING LEARNING ACTIVITIES ....................................................... 22
1
BSc and MSc thesis projects – Laboratory of Food Chemistry
Choosing and performing a thesis research project at the
Laboratory of Food Chemistry
Purpose of a thesis research project
Your thesis research project is an important part of your
study. In the past years you have gained knowledge in
food science with the aid of teachers and supervisors
during lectures, laboratory classes, computer classes,
etc. You learned obtaining information by literature
searches, internet searches, performing experiments,
evaluating your results and writing reports and/or giving
presentations. Also, you have started to a certain extent
to develop a scientific way of reasoning on how to solve
problems. The purpose of a thesis project is to further
develop this skill to analyse and solve a problem in a
scientific way. In addition, a thesis project also perfectly
serves the objective of obtaining knowledge/insight in a
specific area of research.
A thesis research project at the Laboratory of Food Chemistry
After you have chosen a research project, you will start-up this project together with
your supervisor. The supervisor is usually a researcher from our Laboratory. In short,
you will make a research plan, perform experiments by using our equipment and give
some presentations to your fellow-students. The project is finalised with a report and a
final presentation (colloquium).
A thesis research project in Food Chemistry is related to a specific (bio)chemical food
product or biomass conversion issue, which on its turn is related to an industrial
application. In this way we do not solve an industrial problem, as this is the task of our
graduates once they work in industry. Instead, we aim at understanding the mechanisms
behind the problems and we aim to approach this in an academic way. With this
knowledge/insight students are enabled to address (yet unknown) future problems, once
they are graduated.
Within the Laboratory of Food Chemistry we focus our research on a limited number of
topics. By doing so we are able to maintain our internationally well recognized position.
This is also of benefit for students, as on the one hand their research project is well
embedded and on the other hand it is a good reference regarding future employment. As
a consequence the number of areas of research possible for thesis projects is somewhat
restricted. In addition, to guarantee an optimal supervision, it is not always possible to
choose the subject of your interest. This can be due to the fact that other students have
already chosen the subject and for optimal supervision we want to restrict the number of
students per supervisor.
The main research topics of our Laboratory are (see also Table of Contents):
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Part
Part
Part
Part
Part
1:
2:
3:
4:
5:
Quality and/or processing of food (raw) materials
Enzymatic or fungal upgrading of food (raw) materials
Health aspects of food
New and/or improved ingredients for food
Educational development
Within these topics we deal with several foods and food raw materials such as dairy
products, cereals, fruits, vegetables, legumes, beverages (coffee, tea, beer), etc.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Choosing a thesis research project
First, formulate for yourself what specific knowledge/skills you want to learn during the
thesis project. If you are e.g. interested in enzymology use this aspect for making your
choice.
Second, is the background of the subject motivating you? If you do not like the
background of the subject it will decrease the chance of success. Be aware that although
it might be interesting to work on an industrial problem or product, it is the underlying
way of performing research that is most important. By doing this you are, as stated
above, enabled to address any industrial future problem. In order to acquire a solid
background in food chemistry this can usually be trained better if one works with specific
components of food rather than with the complete food product itself.
On the following pages you can find the description of the research topics followed by
information on specific thesis projects.
I am sure you will be able to find a subject that fits you. Many students have preceded
you and enjoyed their thesis projects.
prof.dr.ir. Harry Gruppen.
Chair of Food Chemistry
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Part 1: Quality and/or processing of food (raw) materials
Effect of the Maillard reaction on protein digestibility (dairy subject)
The Maillard reaction occurs during thermal processing of food such as baking, roasting,
brewing and etc. It can also happen by design to improve the techno-functional
properties of proteins, e.g. emulsion and foam stability. In the early stage of the
reaction, the Maillard reaction is between the amino group of a protein and the reducing
end of a carbohydrate (glycation). In the later stage, the Maillard reaction can lead to
protein cross-linking (aggregation). Previous research showed that both phases influence
the protein enzymatic hydrolysis. Proteases are characterized by specificity and
selectivity. It is expected that the trypsin hydrolysis (specific for lysine/arginine, the
same as glycation) will be negatively affected by glycation. Other proteases (nonlysine/arginine specific) might also be affected by glycation and/or aggregation. We
would like to study how much the Maillard reaction influences protein enzymatic
hydrolysis and to understand the mechanism of it at a molecular level.
In vitro enzymatic hydrolysis is used to
mimic gastrointestinal digestion.
Analytical tools such as pH-stat and LCMS are used to identify and quantify the
glycation/aggregation and peptide
formation.
Thesis project:
• The effect of substrate concentration on protein enzymatic hydrolysis
The role of Maillard reactions in Protein Foam stability (dairy subject)
The foam stability of proteins is of relevance to many food products. While many studies
have been performed to find the link between the properties of the proteins and the
resulting foam such a link has not yet been established. In recent research evidence was
found for the effect of Maillard induced aggregation of proteins in the formation and
stabilization of foam. In this way the functional properties of the proteins could be
boosted significantly in a relatively simple process.
The Maillard reaction starts by linking one saccharide to a free amino-group of a
protein. We observed that as a result of this reaction the proteins started to form
oligomers and small aggregates. Exactly these oligomers and aggregates will be the
subject of study. By selective treatment, or modification of proteins well-defined ‘model’
systems will be produced. These systems should be characterized to the type of
aggregation that was obtained (size, size-distribution, charge or hydrophobicity).
Thesis projects:
 Firstly the effect of conditions (protein type, sugar type, temperature / time) will
be studied. Also other reactions than the Maillard reaction could be used to induce
oligomer formation. After formation and characterization of the chemical
properties, some assays can be used to test the changes in foam properties of the
modified variants.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Ingredients, Interfaces and Ice cream (dairy subject)
Ice cream consists for 50 % of air. The air bubbles are stabilised by mixtures of dairy
proteins and low molecular weight (LMW) surfactants. In the production, first the LMW
surfactants adsorb to the interface. Later in the process, the LMW surfactants are
displaced from the interface by the adsorption of proteins. If novel ingredients are used,
this subtle balance between adsorption and desorption is easily disturbed, which can lead
to undesired product properties.
Ingredients
Interfaces
Ice cream
T0
T1
To control the stability of foam in mixed protein – surfactant systems, the interactions of
proteins and surfactants in the interface needs to be understood. In this project, you will
investigate how the chemical properties of proteins and LMW surfactants alter the
adsorption and desorption of these compounds in mixed systems and relate it to the
stability of foam made from mixed solutions.
Thesis projects:
 Investigation of interactions of mixed systems of proteins and LMW surfactants in
bulk solution
o Structure and physico-chemical properties of proteins (e.g. CD, DSC and
protein charge)
o Foam and interfacial properties of mixed systems
You will determine these properties in a well-defined system of dairy proteins and a nonionic surfactant in order to investigate the formation of hydrophobic complexes of protein
and surfactants.
The project will involve techniques to determine foam properties (FoamScan), interfacial
properties (automated drop tensiometer) and bulk characteristics (CD, ESI-MS,
Nanosizer).
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Free radical intermediates produced during primary lipid oxidation in O/W food
emulsions
Food emulsions (O/W) such as mayonnaise and salad dressing are very prone to
deterioration caused by lipid oxidation. The dispersed oil droplets contain unsaturated
fatty acid chains that can be readily oxidized via diverse mechanisms.
The first pathway of this oxidation is a free radical chain reaction, leading to
hydroperoxide formation. Degradation of these hydroperoxides leads to the formation of
so-called secondary oxidation products (e.g. aldehydes, epoxides), which are responsible
for the rancidity and off-flavor of O/W food emulsion products. The mechanistical
pathways of lipid oxidation have been partly unraveled in bulk oils. However, in food
emulsions, both chemical and colloidal effects come into play. Unravelling of these
mechanisms is hampered by lack of knowledge on unstable radical intermediates.
This project will focus on the initial stage of primary oxidation and the transition stage
between primary and secondary oxidation. Here we will aim to identify and quantify the
radical intermediates by Electron Spin Resonance (ESR). This technique allows for the
detection of stable radicals. In lipid oxidation, formed radicals are very reactive and
short-lived, making it impossible to analyze them as such. To tackle this problem, socalled spin-traps can be used. The emulsion matrix adds significant complexity to the
applicability of a spin-trap, which needs to be considered when selecting the right spintrap. Ultimately, the ESR-method will be applied in shelf-life tests, where we want be
able to resolve the formation of specific radicals in time.
ESR-facilities are located in the Helix building at the WUR-campus. Samples will be
generated in collaboration with Unilever R&D Vlaardingen.
Thesis projects
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Identification and quantification of free radical intermediates produced during
primary lipid oxidation in O/W food emulsions by ESR
Isolation and identification of hydroperoxides (LC-MS + NMR)
New analytical techniques for research on food
During the last years a lot of new techniques and technologies were introduced which
allows the food chemist to monitor reactions which take place in agricultural products
during storage and processing. Nowadays it is possible to monitor chemical reactions in
food products which was impossible only a few years ago. The discipline of proteomics
would not have evolved so quickly without the development of advanced mass
spectrometry techniques. Therefore, it is now possible to determine the structure of
complex mixtures of bio molecules.
The techniques which are available and used at the Laboratory of Food Chemistry are
described well. But for the introduction of these new techniques for the monitoring of
different components it is sometimes necessary to carry out methodology research. For
example: the quantification of components when new HPLC detectors are used, the
better understanding of the fragmentation reactions which take place during the
ionization of oligosaccharides in the LC-MS or the improvement of HPLC separation of
complex mixtures of polysaccharides. The student should have a good perception of
analytical techniques.
Thesis projects:
 Application of LC-MS, MALDI-TOF MS, HPLC.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Part 2: Enzymatic or fungal upgrading of food (raw) materials
Upgrading lignin – future as natural ingredient for food & feed or natural
chemicals?
Upgrading lignin, one of the most abundant polymers in nature, has already been a challenge for
decades. Excitingly, with recent and new analytical possibilities, revealing the black box of lignin
comes into reach! Hence, now, possibilities to upgrade lignin may open up new ways towards natural
ingredients for food & feed products or as natural chemicals, e.g. as anti-oxidants or anti-microbials.
Biological conversion of lignin, or lignin-rich raw
materials, plays a role during the cultivation of
mushrooms. Vice versa, fungi are an interesting
tool to modify, degrade or convert lignin. The
exact effect of (various) fungi on the lignin
structure is unknown. In addition, it is known that
certain fungal species produce enzymes, which
may alter or degrade lignin structures – however,
underlying mechanisms are unknown.
To accommodate development of new ingredients
from lignin, the relation between the lignin
structure and possible enzyme or fungal effects
on this structure needs to be fully understood.
Hereto, the chemical structure and quantification
of lignin is required for which isolation of
(various) lignin fractions, a highly challenging
task, is aimed at.
In this project a newly developed method for lignin analysis (pyrolysis coupled to gas chromatography
with mass spectrometric detection (py-GC/MS)) is employed as tool for both quantification and
structural characterisation of lignin. While py-GC/MS-characterisation of lignin is in place,
quantification requires further development of the method.
Different strategies might be employed to upgrade/alter lignin, such as enzyme incubation, fungal
growth and chemical degradation.
Thesis projects:
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Mild isolation and characterisation of lignin from various raw materials, including
mapping lignin/ phenolic compounds-like structures in the various fractions obtained.
Method development for quantitative lignin analysis with py-GC/MS.
Effect of fungal growth or enzymes for upgrading/altering lignin (examples of relevant
analytics are py-GC/MS, HPSEC or UPLC-MS).
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Can laccase-mediator systems upgrade lignin: new natural ingredients?
Lignin is a polymeric aromatic structure in plant cell walls, and is one of the most
abundant polymeric materials in nature. Its insolubility and recalcitrance to enzymatic
breakdown make lignin breakdown one of the largest challenges in biorefinery.
Although challenging, enzymatic breakdown of lignin may open up new ways towards
natural ingredients for food & feed products or as natural chemicals, e.g. as anti-oxidants
or anti-microbials.
Laccases are among the few enzymes that show activity towards lignin. These enzymes
couple the reduction of O2 to the one-electron oxidation of aromatic substrates. For the
oxidation of the majority of the lignin subunits, it is necessary to combine laccase with a
mediator (a small molecule that acts as electron carrier between enzyme and substrate).
The initial oxidation of lignin by laccase-mediator systems has been suggested to result
in a competition between lignin depolymerization, ketone formation at the C α atoms, or
lignin polymerization. Currently, it is poorly understood how this competition is balanced.
O2
Mediator·
H2O
Mediator
Polymerization?
Depolymerization?
Ketone formation?
Before laccase-mediator systems (LMS) can be applied to result in new natural
ingredients, we need to be able to predict the effect of these systems on the substrate
structure.
This project aims at understanding how laccase-mediators act on lignin or lignin-like
structures. The focus is on the competition between polymerization, depolymerization
and Cα oxidation of lignin, as initiated by laccase-mediator systems.
Attention is paid to the influence of mediator types, lignin structure and reaction
conditions.
Thesis projects:
 Understand the effect of LMS on model dimers, that represent structures of
industrial lignins (UHPLC-MS).
 Understand the influence of mediator type on LMS reactions, including product
profiling (UHPLC-MS, O2 consumption).
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Part 3: Health aspects of food
Enhancing the production of plant metabolites with antimicrobial activity
Prenylation as a tool to diversify and enhance antimicrobial properties of phenolic compounds
Plants of various species are known to produce defence compounds when they are
exposed to stress. These defence compounds can possess antimicrobial activity. The
process of prenylation, substitution with a
prenyl-group (C5), can be performed in vivo or in vitro. We are working with plants of
the family Leguminosae, currently focussed on peanuts which produce prenylated
stilbenoids during micro-malting combined with fungal stress. Prenylation plays a key
role in the functionality of phenolic compounds and has been shown to modulate
antimicrobial activity of flavonoids and stilbenoids. In addition, we are applying similar
methodologies on benzoxazinoids, a class of defence compounds found in several species
of grains (e.g. wheat, rye, barley).
To summarise, we will employ different approaches to produce antimicrobial (prenylated)
compounds:
In vivo:
- Micro-malting: germination of plant seeds combined with exposure of seedlings to
fungal growth.
In vitro:
- Prenyltransferases (PTs): Prenyltransferase enzymes can be produced by
genetically modified E. coli. PTs can then be used to attach prenyl-groups to
various phenolic compounds.
- Chemical prenylation: Prenylation of flavonoids and stilbenoids via organic
synthesis.
Germinator used in micro-malting,
normally used in the beer brewing
industry for pilot-scale malting
Example of a prenylation reaction, the
stilbenoid resveratrol is substituted with a
prenyl-group.
Thesis projects:
Thesis projects will include a combination of practical work in the fields of chemistry and
microbiology.
 Micro-malting seeds with the germinator combined with fungal challenging. This
will be followed by extraction, fractionation, purification, and characterisation of
phenolic compounds by (preparative) liquid chromatography (LC) and mass
spectrometry (MS).
 Targeted production of prenylated phenolic compounds with microbial
prenyltransferases (PTs). This will involve practical work in genetic modification of
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BSc and MSc thesis projects – Laboratory of Food Chemistry
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bacteria and purification of the produced PTs. Prenylated phenolics will be
analysed by LC-MS.
Organic synthesis of prenylated phenolic compounds. Optimisation of the
production of (specific) prenylated flavonoids or stilbenoids. Products will be
analysed by LC-MS and NMR. The product molecules will be purified using
preparative LC.
Antimicrobial testing of the aforementioned compounds, and investigation of the
structure-activity relationship and mechanism of antimicrobial activity.
Structure activity relationships of isoflavonoids as antimicrobial agents
At present there is a great concern about
the emergence of multidrug resistant
bacterial strains, and continuous research
efforts are being devoted for the
development of new and effective
antimicrobial agents. Many plants from the
Leguminosae family have been used for
medicinal purposes since ancient times in
many parts of the world. Therefore,
substantial attention has been focused on
the exploration and utilization of legume
phytochemicals as alternatives of traditional
antimicrobial agents.
Previous studies have found these plants to be rich in isoflavonoids. Isoflavonoids are
phenolic plant secondary metabolites, and are produced as part of the plant defence
system. Isoflavonoids have been shown to exhibit interesting biological and
pharmacological properties, such as antioxidant, antibacterial, antiviral and antiinflammatory activity. These properties seem to be highly structure-dependent.
Prenylation is a type of substitution commonly found in bioactive isoflavonoids. Some
prenylated isoflavonoids have shown strong inhibitory activity towards antimicrobial
resistant strains, as well as synergy with traditional antimicrobials. However, the exact
relation between chemical structure (e.g. number, type and position of substituents in
the isoflavonoid skeleton) and bioactivity is not yet well understood.
In order to develop novel and effective antimicrobials it is necessary to fully understand
these structure-activity relationships (SAR), and elucidate the main chemical features
necessary to have good antimicrobial activity. Different strategies might be employed to
enhance the antimicrobial potential of these compounds (e.g. fermentation, enzymatic
prenylation).
Thesis projects
In general, thesis projects will include practical work from both chemistry and
microbiology.
 Characterization and purification of antimicrobial isoflavonoids present in seed
extracts by chromatographic techniques, such as UPLC-MS and preparative HPLC,
in order to determine the main structure-activity relationships.
 Elucidation of the mode of action of the main antimicrobial compounds using
different biochemical assays.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Antimicrobial Phytochemicals from Brassica
There is a growing interest in finding novel antimicrobial agents because of the increasing
incidence of antibiotic resistance. Nonetheless, finding new potential antimicrobial agents
against pathogenic Gram-negative bacteria is a challenge due to their specific feature,
called efflux pump system. Previous research in Laboratory of Food Chemistry has shown
that prenylated (iso)flavonoids from elicited legume sprouts do not show growth
inhibition in Gram-negative bacteria, e.g. Escherichia coli when there is no efflux pump
inhibitor being used.
Therefore, we are now investigating antimicrobial property of other types of plant
secondary metabolites from different plant family, namely Brassicaceae. We are also
extending the investigation on antimicrobial activity against yeast and fungi which cause
food spoilage.
Brassica is characterized by glucosinolates (GSL) and sulfur-containing alkaloid. Both are
involved in the plant defense giving an indication that they are potentially antimicrobial.
Furthermore, GSL is hydrolysed in a presence of myrosinase, a thioglucosidase. In
neutral pH, it forms isothiocyanates (ITC) which have been reported to have
antimicrobial property. However, there is lack of systematic study on their mode of action
as well as structure-activity relationship.
Besides, we are also interested in studying the hydrolysis of GSL and the stability of ITC
being formed. For this, we need to design an analytical procedure to monitor the
presence of ITC both qualitatively and quantitatively using UHPLC-MS analysis.
Thesis projects
In general, thesis projects will include practical work from both chemistry and
microbiology.
 Develop an analytical method to simultaneously monitor GSL, ITC, and sulfurcontaining alkaloids both qualitatively and quantitatively using UHPLC-MS
 Study the GSL hydrolysis by myrosinase and the stability of ITC in aqueous
solution upon different temperatures and pHs
 Study the mode of action of the main antibacterial compounds
 Study the antifungal activity of ITC, GSL, and alkaloids against yeast and fungi
and their mode of action
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Effects of processing of proteins on their immunogenicity: allergy as a model
(dairy subject)
Food allergy develops in two phases: a sensitisation phase and an elicitation phase, the
latter resulting in clinical symptoms of allergic disease. Sensitisation is the phase during
which immunological priming to the inducing allergen occurs, leading to the evolution of
aTh2-biased immune response and the production of IgE-antibody.
Skewing of adaptive immune response to a Th2-type phenotype and IgE-antibody
production necessarily are preceded by an innate immune response to the allergen.
Activation of receptors on cells of the innate arm of the immune system is crucial for the
initiation of adaptive immune responses.
Processing changes the structural and chemical properties of proteins, and hence of
allergens. Proteins denature, aggregate, bind to lipid structures, and undergo
glycosylation and or glycation (Maillard reaction). These processing-related structural and
chemical changes will influence how the immune system will respond, possibly leading to
eventual allergenicity.
The aim of this project is to study the effect of processing-induced alterations in proteins
(unfolding, fibril formation, aggregation, Maillardation) on the response that they provoke
in (innate) immune cells, such as macrophages and dendritic cells.
Thesis projects:
 Characterisation of processing-induced structural alterations in (model) food
proteins (fluorescence, circular dichroïsm, size, electrophoretic behaviour, etc.)
 Analysis of immune response to such alterations by exposing model cell cultures
to the proteins by immunologic methods such as phagocytosis and cytokine
production
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BSc and MSc thesis projects – Laboratory of Food Chemistry
The Fate of Human Milk Oligosaccharides (HMO) in Infant Gut (dairy subject)
Milk is the first food to fulfil the need for
the neonates. It provides some potentially
significant physiological and biological
functions such as prebiotic, antipathogenic
and immunomodulatory activities that are
partly resulted from oligosaccharides.
Thesis project:
Oligosaccharides present in human milk
and infant faeces will be identified and
quantified by CE-LIF, MALDI-TOF-MS,
HILIC-MS, etc. Mechanisms of
metabolisation, conversion and utilisation
of HMO in infant gut will be proposed.
N-Glycans in bovine and human milk (dairy subject)
Milk is the first source of nutrition for newborns. Newborns have an immature immune
system and milk contains many biofunctional components, such as human milk
oligosaccharides (HMOs) and proteins, that are known to be involved in the development
of the immune system. HMOs not only provide nutrition to the infants but also have
shown to influence the composition of the gut microbiome, modulate the immune
system, and help protect against pathogens. Proteins play a pivotal role in protecting the
gut mucosa against pathogens and are also known to play an important role in the
protection of the mammary gland. Since the proteins in milk are highly glycosylated,
glycans are considered to be a major contributor to this immune system development.
Thesis project:
This project will focus on the release of glyco-tails from the proteins. Recently, there is a
method developed in our lab for the glycation of cow milk proteins which needs
validation. After this the method will be used to analyse the glycosylation patterns of
proteins present in milk from different mothers during lactation.
N-glycans can be detected/identified in bovine milk by LC-MS and MALDI-TOF-MS
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Toward controlled steering of microbiota and immunity in infants by nondigestible carbohydrates
Bacteria colonizing the infant mucosa guide the development of a balanced immune
system and also support maturation of the gut-barrier. Mother-milk has been considered
the golden standard for guiding this colonization. Mother-milk contains energy sources
for microbiota and also supports immune function directly. For those infants where
mother-milk is not a feasible option, cow-milk formulas
supplemented with non-digestible carbohydrates (NDC)
are used. An important function of these NDCs is a
preferred support of Th1-responses responsible for
fighting infections. However, recently it has been found
that not all NDCs currently applied support Th1-responses
and that induced responses are dependent on the
composition of NDCs.
The goal of this project is the design of tailored NDCsupplements for healthy and disease-prone infants who
do not receive mother-milk. In this way the immune
response development with respect to T-cell skewing and
epithelial barrier function will be supported. As a result
the risk of developing allergies or gastrointestinal
disorders in a later stadium of life will be lowered.
Thesis projects:
 Characterization and quantification of NDCs by MALDI-TOF-MS, HILIC-MS etc.
Additional fractionation using AEC, SEC or preparative HILIC-MS will be performed
to unravel the different structures present in the highly complex mixtures.
 Following the fate of selected (fractions of) NDCs during in vitro batch
fermentation using infant faecal inoculum by HILIC-MS and SCFAs analysis using
HPLC and GC. Unknown glycosidic NDC products will be identified by HILIC-MS.
 Analysis of NDCs, their degradation products and SCFAs produced after incubation
in a co-culture system mimicking the infant-gastrointestinal tract (UMC
Groningen)
14
BSc and MSc thesis projects – Laboratory of Food Chemistry
Behaviour and digestibility of starch in pigs
In a world with a rapidly growing population with
a higher demand for animal protein, the global
meat consumption is on the rise. To meet these
increasing demands, efficient and sustainable use
of raw ingredients becomes more and more
important.
Starch is the main storage carbohydrate in plants
and forms an important source of energy in the
diet of humans and animals. Many different
sources of starch are used in food and feed. This
project focusses on studying the chemical and
physical properties of starch from different
sources, and their physical behaviour and
digestibility in a pig model. By gaining a better
insight in the types of starch and their relations
to pig digestibility, more precise models can be
developed to predict the feeding value of the
starch, which will lead to a more efficient use of
the energy in starch.
The main questions to be answered in this project, is how and where different starches
that are present in (processed) feed are digested within a pigs digestive tract, and how
this effects the pig's performance. This project consist of a combination of in vitro (lab)
digestion trials, which will be done to adapt human digestible and resistant starch assays
to the animal situation, and in vivo experiments (in pigs), where digesta of differently fed
animals will be analysed.
Thesis topics:
Within this project various thesis topics are available for BSc as well MSc students.
 Analysis of the effect of the feed matrix and feed processing on starch
digestibility, using newly developed in vitro digestion models.
 Study chemical characteristics of partly digested starch samples from an in vivo
digestibility trial with pigs (February 2016).
 Comparing in vivo intestinal samples from a starch digestibility trial with pigs with
samples from an in vitro digestibility assays (February 2016).
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Carbs can make the difference: how pectins fuel immunity
A disbalance in microbiota communities in the intestine is implicated in a large number of
Western diseases. This correlates with low intake of dietary fibre in Western diets. Pectin
is a dietary fibre that might be essential for prevention of Western diseases. Recently,
evidence has been found that beneficial effects of pectin are highly dependent on its
chemical structure and the effects go beyond prebiotic effects. Earlier research has been
demonstrated that low methyl esterified pectins have direct, microbiota-independent
effects due to their direct interaction with TLRs in the small intestine. High methyl
esterified pectins mainly impact the microbiota in the colon to enhance formation of
pectic oligosaccharides and SCFA.
The aim of our research is to fully characterize bioactive pectins and their intermediate
degradation products upon fermentation by enzymatic fingerprinting techniques.
Pectin molecules from various sources will be applied and enzymatically tailored with a
combined beneficial effect. The already available data on pectin health effects will serve
to produce a mixture of pectins with a desired molecular weight and methyl esterification
pattern, which will be tested (in collaboration with the University Medical Center
Groningen) in mice with a temporary disrupted small-intestinal barrier-function and mice
with a disrupted colonic-integrity. Results obtained will be used to further tailor pectin
structure to yield optimal bioactivity.
This study will contribute to the understanding of the structure-function relationship of
pectins.
Thesis



topics:
Enzymatic tailoring bioactive pectic polymers.
Chemical characterization of tailored pectins using enzymatic fingerprinting.
Identifying and quantifying intermediate fermentation products from mice digesta
& faeces of pectin fed mice.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
The effect of protein structure on digestion dynamics (dairy subject)
Enzymatic protein hydrolysis finds its interest in protein digestion and availability in the
digestive tract as well as in industrial application of protein hydrolysates as food
ingredient. To be able to predict the exact outcome (hydrolysate composition) of an
enzymatic hydrolysis and thereby predict the bio- and techno-functional properties, the
activity of the proteases should be well understood. Nowadays, the activity of proteases
is mainly explained by its specificity, which indicates after which amino acids the
protease can cleave the peptide bond (e.g. trypsin can cleave after lysine and arginine).
However, in practice it was observed that not all the possible cleavage sites are
hydrolysed to the same extent or some even not at all (DHmax,theoretical≠DHmax,experimental).
This phenomena can be explained by the selectivity of the protease, which indicates the
preference for certain possible cleavage sites within a given specificity (Butré, 2014).
As the selectivity can have a significant influence on the final outcome of the protein
hydrolysis, it is important to understand the mechanism behind selectivity in order to
predict the outcome. It is hypothesized
that in general selectivity can be
explained by the ‘accessibility of’ and
‘affinity to’ a certain cleavage site. It is
thought that the accessibility can be
related to the tertiary structure of the
substrate protein as well as possible
aggregation, and affinity can be
explained by the primary structure
together with possible exposed charges.
The aim of this study is to investigate
the mechanistic factors determining the
selectivity of proteases by performing in vitro protein hydrolysis, using commercially
available proteases and mainly milk proteins as substrate. After hydrolysis, the
hydrolysate composition (peptides and/or intact protein) will be analysed using RP-UPLCUV-MS. From the composition over time, the selectivity can be calculated which can then
be related to the starting conditions/substrate properties.
Thesis projects:
 Describing the relation between tertiary structure of the substrate protein and the preference for
intact protein (zipper-) or released peptides (one-by-one mechanism).
One-by-one
Zipper

Describing the effect of tertiary structure as well as primary structure of different
substrate proteins on the selectivity of trypsin.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
The effect of dairy protein composition on protein digestion kinetics
Proteins are digested in the gastrointestinal tract by proteases, ultimately leading to triand di-peptides and free amino acids (AA) that can be absorbed by the intestinal
epithelium. The epithelium releases free AA into the blood stream. The kinetics of protein
digestion and absorption appear to influence the fate of the AA systemically, i.e.
incorporation in protein or oxidation and secretion as urea.
Protein digestion and absorption kinetics appear to depend on the protein composition. For
example it has been shown in healthy volunteers that the postprandial AA plasma peak
after whey protein ingestion is higher than after casein ingestion. This is usually attributed
to the differences in gastric emptying between the proteins due to their distinct
physicochemical behavior in the stomach. However, we have shown previously that in an
in vitro digestion model enzymatic protein hydrolysis kinetics are also different between
whey and casein proteins. This may contribute to the overall protein digestion and
absorption kinetics as reflected in postprandial AA peak as well.
Enzymatic protein hydrolysis depends on the primary structure of the proteins. Whey and
casein milk fractions are mixtures of proteins with unique primary structures. It is of
interest to further the understanding of the effect of protein composition of protein
mixtures on the overall enzymatic protein hydrolysis kinetics.
Thesis project:

In vitro digestion experiments will be perfomed to simulate gastrointestinal
conditions. Protein hydrolysis kinetics of dairy protein (mixtures) will be monitored
by SDS-PAGE, OPA, HP-SEC and UPLC.
Experiments will be performed at the life-science lab at Nutricia Research on Utrecht
Science Park.
The life-science lab is a ML-II laboratory, therefore vaccination (Hep A+B, DTP) is
mandatory. Not having valid vaccinations means they need to be arranged, via Nutricia
Research, at the latest 6 wks before start.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Part 4: New and/or improved ingredients for food
Use of enzymatic crosslinking to produce protein nanoparticles (dairy subject)
To obtain good product properties, one can choose different types of proteins, coming
from different sources. An alternative is to ‘pre-process’ the proteins to produce protein
isolates with altered functionality. In addition to traditional steps (heating, Maillard),
enzymatic crosslinking can be used in this way.
Currently, peroxidase enzymes have been used to crosslink different
types of proteins. Initial experiments have shown that protein nanoparticles of different sizes (10-80 nm) can be obtained. For these
nanoparticles a significant increase in foam stability was observed. One
of the possible reasons for this is that the particles get stuck between
air-bubbles in a foam, similar to fat globules as in for instance ice-cream.
The aim of this project is to obtain insight in how the size and structure
of crosslinked protein nanoparticles (1) can be controlled by the reaction conditions, and
(2) affect the foam stabilizing properties of the protein.
Thesis projects:
 Comparison of heat-induced aggregates to enzymatically cross-linked proteins.
 Understanding the relation between reaction conditions and the structure / size of
the formed products (protein nanoparticles)
 Study the use of alternative enzymes / substrates in the formation of protein
nanoparticles with different properties.
19
BSc and MSc thesis projects – Laboratory of Food Chemistry
Understanding polysaccharide interactions in fruits and vegetables
The primary plant cell wall in fruits and vegetables is composed of a complex mixture of
pectin, hemicellulose and cellulose. It is proposed that in the current cell wall model two
separate networks co-exist: a
pectic network and a
hemicellulose/cellulose
network. For long time it was
believed that these two
networks are independent but
more and more evidence is
found that interactions
between these 2 networks
exist. However, the nature of
the interactions and the cell
wall components involved are
unknown, species-dependent,
and both hints for covalent and
non-covalent interactions are
found.
Therefore the aim of this project is to understand the architecture of the plant cell wall:
are these polysaccharides linked to each other and if they are, by what kind of linkage?
Thesis projects:
In this project we will address this question in several approaches:
 Enzymatic degradation: by using purified enzymes we degrade the hypothesized
crosslink between the pectin and hemicellulose/cellulose network and characterise
solubilised polysaccharides.
 Chemical extraction: degrading specific linkages by cross-link degradation and
characterisation of solubilised polysaccharides
Both topics are addressed by characterisation of the extracted material with techniques
such as HPSEC, HPAEC, UPLC-MS and MALDI-TOF-MS.
20
BSc and MSc thesis projects – Laboratory of Food Chemistry
IsoMalto/Malto-Polysaccharides (IMMPs): novel polysaccharides from starch.
Starch is a natural polysaccharide that makes up a large part of the human diet. The
compound itself is biodegradable and used in a wide variety of applications. Due to its
relatively low price and its high availability starch is an attractive substrate for
(enzymatic) modification.
The discovery of the GtfB enzyme (4,6-α-glucanotransferase) opens up a new way to
modify starch. This enzyme is able to alter the intrinsic properties of starch by cleaving
α-1,4 glycosidic linkages and introducing α-1,6 glycosidic linkages into the
polysaccharide.
The products of this enzymatic modification are named IsoMalto/Malto-Polysaccharides
(IMMPs), due to the nature of their linkage composition. IMMPs can be considered as a
new generation of polysaccharides with added functionality for products in and outside
the food industry, such as: food fibres, nutraceuticals, texturizers, replacement of
synthetic polymers, biomedical materials and many other possible applications.
The aim of this project is to make the carbohydrates, to map the properties and to
design optimal products for further applications.
Thesis projects:
 In depth chemical analysis of novel polysaccharides, including; molecular weight,
ratio of α-1,4: α-1,6 linkages and directed (enzymatic) modification.
 Physical analysis of novel polysaccharides, including; viscosity, elasticity, gel
strength, glass transition point and directed (enzymatic) modification.
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BSc and MSc thesis projects – Laboratory of Food Chemistry
Part 5: Educational development
Design and/or evaluation of digital learning material for Food Chemistry
Since 2000, the Laboratory of Food Chemistry has been designing and developing digital
learning materials. These materials are used in different courses in the field of food
chemistry. With computer applications, learning material can be designed that can reach
certain learning goals in a more efficient way compared to traditional teaching methods.
The possibilities of digital techniques are amongst others easy visualization, incorporation
of movies or animations, the possibility to personalize the computer program, giving
immediate feedback or hints, and interaction, motivation and activation of students.
This project deals with three different fields: Food Chemistry, Didactics, and Information
and Communication Technology (ICT). It is the combination of these three fields that
makes this project interesting. The goal is to design and/or evaluate useful digital
learning materials. You will learn about educational theories, about using computer
technologies and about a certain subject within food chemistry.
Thesis project:
 Designing digital learning material for a course in the field of food chemistry.
Depending on the interest of the student and the needs of the teachers we can
describe the topic for the thesis project together. Contact [email protected] if
you want to know more about this project.
Developing new learning activities or improving existing learning activities
The Laboratory of Food Chemistry is continuously working to improve our education. One
important development is to develop activating learning activities. Learning activities are
for example laboratory activities, group work, class room activities during lectures,
training questions within readers, etc.
This thesis subject deals with two different fields: Food Chemistry and Didactics. You will
learn how to design and evaluate useful learning activities, by incorporating education
theories, for a certain subject within the field of food chemistry. This means that you will
also gain knowledge about that specific food chemistry subject
Thesis project:
 Designing learning material for activating learning activities for a course in the
field of food chemistry. Depending on the interest of the student and the needs of
the teachers we can describe the topic for the thesis project together. Contact
[email protected] if you want to know more about this project.
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