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Thesis projects of the Biosystematics Group

Below you can find a list of potential research topics that students can work on. We may also be able to accommodate research on your own topic of choice if it matches our expertise.

Our thesis projects

Thesis subject A hitch-hikers guide to egg parasitism

Thesis subject Natural selection of (anti-) sex pheromones by egg parasitoids

Thesis subject Biodiversity on Wageningen Campus

Thesis subject Biodiversity of green roofs

Thesis subject Are grasses with low genetic diversity more susceptible to infection by fungal pathogens?

Thesis subject Exploring the effect of intercropping on root traits and AMF colonization in Brassica-Allium intercropping (from a breeding perspective)

Thesis subject Fluorescence microscopy of insect embryos

Thesis subject Occurrence survey of rust fungi in threatened populations of Yellow star of Bethlehem (Gagea lutea, Bosgeelster) and related species

Thesis subject Comparative genomics and trait evolution of lettuce wild relatives

Thesis subject Elucidating the evolution of symbiosis genes across plant genomes

Thesis subject Bioinformatics & Insect evolutionary development

Thesis subject Resurrecting the past: characterization and evolution of cannabis enzymes

Thesis subject Dissecting Xanthomonas black rot resistance in cabbage

Thesis subject Herbarium genomics to assess wild and landrace diversity in Cannabis sativa

Thesis subject Distribution and variation of downy mildew resistance genes in natural populations of wild lettuce

Thesis subject Ecotypic variability in wild Lambs lettuce populations (Valerianella spp. L - Veldsla)

Thesis subject Evolution of biosynthesis genes in cannabis and hop

Thesis subject How do plants kill butterfly eggs?

Thesis subject Mapping the genes controlling flowering time and vitamin content in the orphan vegetable Gynandropsis gynandra (Cleomaceae)

Thesis subject The black pages of colonial history investigated through the genomic analysis of African rice

Thesis subject Itchy Tropical Tubers -- diversity and evolution of taro [Colocasia esculenta (L.)] and its itchiness

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Water binding and water release by plant-based meat analogues

• Food Technology

Research output : Thesis › internal PhD, WU

The sustainability of the human diet could be improved by lowering meat consumption and offering consumers plant-based meat substitutes as an alternative. Consumers are thought to prefer meat substitutes with a high similarity to real meat. Therefore, meat analogues that accurately mimic the different textural properties of real meat are being developed. Recent advancements in high-moisture extrusion cooking and shear cell processing have enabled the production of fibrous, meat-like products from plant-based ingredients. This has resulted in a wider research scope, which includes other textural properties such as the juiciness. For meat, the juiciness is associated with the water holding capacity (WHC). We have aimed to better understand the uptake, distribution, and release of water of meat analogues. Since these properties relate to the water holding capacity (WHC), this work could help the development of juicier meat analogues.

Meat analogues were simplified to gels consisting of two protein phases, such as soy protein isolate (SPI) and gluten. In Chapter 2 we studied the WHC of two-phase gels with different ratio's between SPI and gluten. The WHC of single-phase SPI gels as a function of applied pressure could be described adequately with Flory-Rehner theory. The WHC of gluten gels was very low and could not be described with Flory-Rehner theory as the WHC did not depend on the applied pressure. Therefore, the WHC of gluten was approximated as a constant when describing the WHC of the two-phase gels. The WHC of SPI gels was found to depend on the polymer content at gelation. This was accounted for by determining the water partitioning before gelation using Flory-Rehner theory. The WHC of SPI in the two-phase gels decreased as gluten content increased. This was explained as the result of a mechanical interaction by which the continuous gluten network lowers the WHC of the entrapped SPI phase. In Chapter 3 the effect of gluten on the WHC was further studied using protein isolates from soy, pea and fababean (SPI, PPI, FPI resp.). Gels made from these protein isolates differed in terms of WHC, with SPI having the highest WHC and FPI the lowest. When combined with gluten, the relative reduction in WHC as a function of gluten content was the same for all three proteins. This suggested that the interaction between gluten and leguminous proteins is universal. A reduction in WHC with increasing gluten content was also observed after thermo-mechanical processing in a shear cell, albeit to a lesser degree. Visual inspection of the structures obtained after thermo-mechanical processing indicated that gluten should contribute ≥ 50% to the total protein content to obtain fibrous structures. Since fibres were also obtained after processing hydrated gluten, we hypothesized that gluten is primarily responsible for fibre formation. The second protein might merely act as a filler and could be easily replaced. The WHC experiments suggested that a continuous gluten network could form already at low gluten contents. Since no fibres were observed at low gluten contents it was suggested that the fraction of gluten should be high enough for them to be observed as fibres.

In Chapter 4 we studied whether the WHC of meat analogues could be controlled during post-processing by varying the pH and ionic strength of the marinade, or by altering the cross-link density. Our experiments showed that the WHC can be increased by lowering the ionic strength or increasing the pH of the marinade. Lowering the cross-link density also led to an increase of the WHC. Similar results were obtained from qualitative simulations using a model based on Flory-Rehner and an extension to account for charge effects. The simulations showed that the difference between the iso-electric point (pI) and the internal pH of the meat analogue strongly affects the WHC. At low ionic strengths, the meat analogue's internal pH can deviate from the pH of the marinade due to the buffering effect of proteins and the requirement of electro-neutrality inside and outside the protein network. The results showed that marinade pH and ionic strength offer control over the WHC and that low-salt marinades might improve juiciness. %, which do not have internal cavities, , which do have internal cavities.

The release of water during mastication is considered essential to the perception of juiciness. In Chapter 5 we developed a confined compression cell to measure the dynamics of juice release for SPI gels and meat analogues. The release rates for SPI gels were in good agreement with model simulations based on Flory-Rehner theory and Darcy's law. The release rates for meat analogues were greatly underestimated by the model, especially for low applied pressures. Time domain nuclear magnetic resonance (TD-NMR) results indicated the presence of water-filled cavities within the meat analogue. This water was expelled at a lower pressure than the water inside the protein matrix. The water-filled cavities can provide a path of low resistance, which explains the higher measured water release rates. The porous structure of meat analogues, therefore, appears to be important for their water release properties. Control over the porous structure of meat analogues could, therefore, offer an additional tool to control the juiciness.

Since the WHC of meat analogues is related to their structure, control over the WHC, and presumably the juiciness, will require a good understanding of their production process. Meat analogues are most commonly produced through thermo-mechanical processing with high moisture extrusion cooking (HMEC) or with a shear cell. In Chapter 6 we reviewed these two processes by describing the physicochemical changes induced during the different processing steps. The processes consist of the same three steps: mixing and hydration, thermo-mechanical treatment, and cooling. Knowledge gaps were identified concerning the effect of thermo-mechanical treatment on protein-protein interactions and the formation of the fibrous structure. Filling these gaps will require more experimentation at process conditions and could improve control of the process and product. The use of food and non-food model systems could support this by allowing for more controlled experimentation.

In Chapter 7 we reflect on our findings in a broader context. The different underlying assumptions of Flory-Rehner theory are discussed. Most assumptions are considered plausible for protein-based meat analogues, although the physical meaning of the model parameters might be limited. The use of physical models is expected to contribute to the development of better meat analogues in the future. Some suggestions are made on how to produce a juicy meat analogue under the assumption that the juiciness largely depends on the WHC. Although the relation between the WHC and the sensory juiciness is yet to be confirmed, we propose that juiciness could be considered a structure-function relationship. The juiciness is a complex sensory attribute with several contributing factors. Since we have only focused on the WHC, future research should explore the relative importance of the WHC as well as the other contributing factors, such as flavour, texture and salivating action. Given the interconnectedness of the different factors and the possibility of cross-modal perception, a high level of control over the product properties will be required. The level of control will largely depend on the level to which we understand the relations between ingredient properties, process parameters, and product properties.

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• 10.18174/539894

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• Water Holding Capacity Food Science 100%
• Water Binding Food Science 100%
• Meat Analog Food Science 60%
• Juiciness Food Science 35%
• Soy Protein Food Science 35%
• Meat Food Science 17%
• Cooking Food Science 7%
• Diet Food Science 3%

Projects per year

Towards a next generation meat analogues

Cornet, S., van der Goot, A. J. & van der Sman, R.

13/02/17 → 26/03/21

Project : PhD

• Water Binding 100%
• Water Holding Capacity 100%
• Meat Analog 60%
• Soy Protein 35%
• Juiciness 35%

T1 - Water binding and water release by plant-based meat analogues

AU - Cornet, Steven H.V.

N1 - WU thesis 7765 Includes bibliographical references. - With summary in English

PY - 2021/3/26

Y1 - 2021/3/26

N2 - The sustainability of the human diet could be improved by lowering meat consumption and offering consumers plant-based meat substitutes as an alternative. Consumers are thought to prefer meat substitutes with a high similarity to real meat. Therefore, meat analogues that accurately mimic the different textural properties of real meat are being developed. Recent advancements in high-moisture extrusion cooking and shear cell processing have enabled the production of fibrous, meat-like products from plant-based ingredients. This has resulted in a wider research scope, which includes other textural properties such as the juiciness. For meat, the juiciness is associated with the water holding capacity (WHC). We have aimed to better understand the uptake, distribution, and release of water of meat analogues. Since these properties relate to the water holding capacity (WHC), this work could help the development of juicier meat analogues.Meat analogues were simplified to gels consisting of two protein phases, such as soy protein isolate (SPI) and gluten. In Chapter 2 we studied the WHC of two-phase gels with different ratio's between SPI and gluten. The WHC of single-phase SPI gels as a function of applied pressure could be described adequately with Flory-Rehner theory. The WHC of gluten gels was very low and could not be described with Flory-Rehner theory as the WHC did not depend on the applied pressure. Therefore, the WHC of gluten was approximated as a constant when describing the WHC of the two-phase gels. The WHC of SPI gels was found to depend on the polymer content at gelation. This was accounted for by determining the water partitioning before gelation using Flory-Rehner theory. The WHC of SPI in the two-phase gels decreased as gluten content increased. This was explained as the result of a mechanical interaction by which the continuous gluten network lowers the WHC of the entrapped SPI phase. In Chapter 3 the effect of gluten on the WHC was further studied using protein isolates from soy, pea and fababean (SPI, PPI, FPI resp.). Gels made from these protein isolates differed in terms of WHC, with SPI having the highest WHC and FPI the lowest. When combined with gluten, the relative reduction in WHC as a function of gluten content was the same for all three proteins. This suggested that the interaction between gluten and leguminous proteins is universal. A reduction in WHC with increasing gluten content was also observed after thermo-mechanical processing in a shear cell, albeit to a lesser degree. Visual inspection of the structures obtained after thermo-mechanical processing indicated that gluten should contribute ≥ 50% to the total protein content to obtain fibrous structures. Since fibres were also obtained after processing hydrated gluten, we hypothesized that gluten is primarily responsible for fibre formation. The second protein might merely act as a filler and could be easily replaced. The WHC experiments suggested that a continuous gluten network could form already at low gluten contents. Since no fibres were observed at low gluten contents it was suggested that the fraction of gluten should be high enough for them to be observed as fibres.In Chapter 4 we studied whether the WHC of meat analogues could be controlled during post-processing by varying the pH and ionic strength of the marinade, or by altering the cross-link density. Our experiments showed that the WHC can be increased by lowering the ionic strength or increasing the pH of the marinade. Lowering the cross-link density also led to an increase of the WHC. Similar results were obtained from qualitative simulations using a model based on Flory-Rehner and an extension to account for charge effects. The simulations showed that the difference between the iso-electric point (pI) and the internal pH of the meat analogue strongly affects the WHC. At low ionic strengths, the meat analogue's internal pH can deviate from the pH of the marinade due to the buffering effect of proteins and the requirement of electro-neutrality inside and outside the protein network. The results showed that marinade pH and ionic strength offer control over the WHC and that low-salt marinades might improve juiciness. %, which do not have internal cavities, , which do have internal cavities.The release of water during mastication is considered essential to the perception of juiciness. In Chapter 5 we developed a confined compression cell to measure the dynamics of juice release for SPI gels and meat analogues. The release rates for SPI gels were in good agreement with model simulations based on Flory-Rehner theory and Darcy's law. The release rates for meat analogues were greatly underestimated by the model, especially for low applied pressures. Time domain nuclear magnetic resonance (TD-NMR) results indicated the presence of water-filled cavities within the meat analogue. This water was expelled at a lower pressure than the water inside the protein matrix. The water-filled cavities can provide a path of low resistance, which explains the higher measured water release rates. The porous structure of meat analogues, therefore, appears to be important for their water release properties. Control over the porous structure of meat analogues could, therefore, offer an additional tool to control the juiciness.Since the WHC of meat analogues is related to their structure, control over the WHC, and presumably the juiciness, will require a good understanding of their production process. Meat analogues are most commonly produced through thermo-mechanical processing with high moisture extrusion cooking (HMEC) or with a shear cell. In Chapter 6 we reviewed these two processes by describing the physicochemical changes induced during the different processing steps. The processes consist of the same three steps: mixing and hydration, thermo-mechanical treatment, and cooling. Knowledge gaps were identified concerning the effect of thermo-mechanical treatment on protein-protein interactions and the formation of the fibrous structure. Filling these gaps will require more experimentation at process conditions and could improve control of the process and product. The use of food and non-food model systems could support this by allowing for more controlled experimentation.In Chapter 7 we reflect on our findings in a broader context. The different underlying assumptions of Flory-Rehner theory are discussed. Most assumptions are considered plausible for protein-based meat analogues, although the physical meaning of the model parameters might be limited. The use of physical models is expected to contribute to the development of better meat analogues in the future. Some suggestions are made on how to produce a juicy meat analogue under the assumption that the juiciness largely depends on the WHC. Although the relation between the WHC and the sensory juiciness is yet to be confirmed, we propose that juiciness could be considered a structure-function relationship. The juiciness is a complex sensory attribute with several contributing factors. Since we have only focused on the WHC, future research should explore the relative importance of the WHC as well as the other contributing factors, such as flavour, texture and salivating action. Given the interconnectedness of the different factors and the possibility of cross-modal perception, a high level of control over the product properties will be required. The level of control will largely depend on the level to which we understand the relations between ingredient properties, process parameters, and product properties.

AB - The sustainability of the human diet could be improved by lowering meat consumption and offering consumers plant-based meat substitutes as an alternative. Consumers are thought to prefer meat substitutes with a high similarity to real meat. Therefore, meat analogues that accurately mimic the different textural properties of real meat are being developed. Recent advancements in high-moisture extrusion cooking and shear cell processing have enabled the production of fibrous, meat-like products from plant-based ingredients. This has resulted in a wider research scope, which includes other textural properties such as the juiciness. For meat, the juiciness is associated with the water holding capacity (WHC). We have aimed to better understand the uptake, distribution, and release of water of meat analogues. Since these properties relate to the water holding capacity (WHC), this work could help the development of juicier meat analogues.Meat analogues were simplified to gels consisting of two protein phases, such as soy protein isolate (SPI) and gluten. In Chapter 2 we studied the WHC of two-phase gels with different ratio's between SPI and gluten. The WHC of single-phase SPI gels as a function of applied pressure could be described adequately with Flory-Rehner theory. The WHC of gluten gels was very low and could not be described with Flory-Rehner theory as the WHC did not depend on the applied pressure. Therefore, the WHC of gluten was approximated as a constant when describing the WHC of the two-phase gels. The WHC of SPI gels was found to depend on the polymer content at gelation. This was accounted for by determining the water partitioning before gelation using Flory-Rehner theory. The WHC of SPI in the two-phase gels decreased as gluten content increased. This was explained as the result of a mechanical interaction by which the continuous gluten network lowers the WHC of the entrapped SPI phase. In Chapter 3 the effect of gluten on the WHC was further studied using protein isolates from soy, pea and fababean (SPI, PPI, FPI resp.). Gels made from these protein isolates differed in terms of WHC, with SPI having the highest WHC and FPI the lowest. When combined with gluten, the relative reduction in WHC as a function of gluten content was the same for all three proteins. This suggested that the interaction between gluten and leguminous proteins is universal. A reduction in WHC with increasing gluten content was also observed after thermo-mechanical processing in a shear cell, albeit to a lesser degree. Visual inspection of the structures obtained after thermo-mechanical processing indicated that gluten should contribute ≥ 50% to the total protein content to obtain fibrous structures. Since fibres were also obtained after processing hydrated gluten, we hypothesized that gluten is primarily responsible for fibre formation. The second protein might merely act as a filler and could be easily replaced. The WHC experiments suggested that a continuous gluten network could form already at low gluten contents. Since no fibres were observed at low gluten contents it was suggested that the fraction of gluten should be high enough for them to be observed as fibres.In Chapter 4 we studied whether the WHC of meat analogues could be controlled during post-processing by varying the pH and ionic strength of the marinade, or by altering the cross-link density. Our experiments showed that the WHC can be increased by lowering the ionic strength or increasing the pH of the marinade. Lowering the cross-link density also led to an increase of the WHC. Similar results were obtained from qualitative simulations using a model based on Flory-Rehner and an extension to account for charge effects. The simulations showed that the difference between the iso-electric point (pI) and the internal pH of the meat analogue strongly affects the WHC. At low ionic strengths, the meat analogue's internal pH can deviate from the pH of the marinade due to the buffering effect of proteins and the requirement of electro-neutrality inside and outside the protein network. The results showed that marinade pH and ionic strength offer control over the WHC and that low-salt marinades might improve juiciness. %, which do not have internal cavities, , which do have internal cavities.The release of water during mastication is considered essential to the perception of juiciness. In Chapter 5 we developed a confined compression cell to measure the dynamics of juice release for SPI gels and meat analogues. The release rates for SPI gels were in good agreement with model simulations based on Flory-Rehner theory and Darcy's law. The release rates for meat analogues were greatly underestimated by the model, especially for low applied pressures. Time domain nuclear magnetic resonance (TD-NMR) results indicated the presence of water-filled cavities within the meat analogue. This water was expelled at a lower pressure than the water inside the protein matrix. The water-filled cavities can provide a path of low resistance, which explains the higher measured water release rates. The porous structure of meat analogues, therefore, appears to be important for their water release properties. Control over the porous structure of meat analogues could, therefore, offer an additional tool to control the juiciness.Since the WHC of meat analogues is related to their structure, control over the WHC, and presumably the juiciness, will require a good understanding of their production process. Meat analogues are most commonly produced through thermo-mechanical processing with high moisture extrusion cooking (HMEC) or with a shear cell. In Chapter 6 we reviewed these two processes by describing the physicochemical changes induced during the different processing steps. The processes consist of the same three steps: mixing and hydration, thermo-mechanical treatment, and cooling. Knowledge gaps were identified concerning the effect of thermo-mechanical treatment on protein-protein interactions and the formation of the fibrous structure. Filling these gaps will require more experimentation at process conditions and could improve control of the process and product. The use of food and non-food model systems could support this by allowing for more controlled experimentation.In Chapter 7 we reflect on our findings in a broader context. The different underlying assumptions of Flory-Rehner theory are discussed. Most assumptions are considered plausible for protein-based meat analogues, although the physical meaning of the model parameters might be limited. The use of physical models is expected to contribute to the development of better meat analogues in the future. Some suggestions are made on how to produce a juicy meat analogue under the assumption that the juiciness largely depends on the WHC. Although the relation between the WHC and the sensory juiciness is yet to be confirmed, we propose that juiciness could be considered a structure-function relationship. The juiciness is a complex sensory attribute with several contributing factors. Since we have only focused on the WHC, future research should explore the relative importance of the WHC as well as the other contributing factors, such as flavour, texture and salivating action. Given the interconnectedness of the different factors and the possibility of cross-modal perception, a high level of control over the product properties will be required. The level of control will largely depend on the level to which we understand the relations between ingredient properties, process parameters, and product properties.

UR - https://edepot.wur.nl/539894

U2 - 10.18174/539894

DO - 10.18174/539894

M3 - internal PhD, WU

SN - 9789463956918

PB - Wageningen University

CY - Wageningen

BSc-MSc Thesis and Internship Projects, Wageningen University

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International Students blog

Master thesis in wageningen – part 1.

By Arun Krishna

At the heart of every two-year master’s degree offered in Wageningen is the master’s thesis which starts in the second year. I started mine two months ago, in September. In this article, I will briefly take you through the important things to know before starting a thesis in Wageningen. 

Compulsory Courses

If you are new to Wageningen or are planning to start your masters here, then you should probably know that the academic departments in Wageningen offer a few compulsory courses to students in order to start a thesis with them. Once you join Wageningen, you will be assigned a study advisor. Take their help to find out more about the compulsory courses that you will have to take for the departments that interest you. I would suggest to do it as soon as you arrive here.

Most of the time, students end up taking these courses towards the end of their first year. So, you still will have lots of time in choosing the department where you wish to do your thesis.  If these courses are not completed on time, it could potentially delay the start of your thesis within a department.

Finding a topic of interest

While this might also seem straight forward, it might often not be the case. A student can easily get lost in the many options that are available to him/her.  Each department in Wageningen(for example Environmental Technology) has different chair groups that work on specific societal goals(like reusing water, recovering metals). I looked at the societal goal that appealed to the most and applied to that chair group. This might be a nice way to filter out topics, especially for confused brains. It is also good to talk to people(seniors, student peers, professors, PhDs ) who are studying or have studied similar topics before you to gain more insight into what topics are currently relevant to research on.

Each department also has a thesis coordinator that helps students find topics. Another way to look at the topics is by searching on the department website. Always look out for department thesis markets, where various topics are put in display and are often presented by the people working with them.

Try to start finding topics that interest you around four to six months in advance . For students that start their thesis in September, that is around March-April. There might be situations where more than one student might be interested in one particular topic, and in that case, students might have to compete with each other. So it is always better to start early, to get the topic that you like. Once you find out topics that interest you, find out how the application for the department of your interest works. The application for every department works very differently .

Thesis Contract

This is very important! Once you have completed your prerequisite courses and found a topic of interest, the next step is to find a supervisor who can supervise your thesis on the very same topic. Contact t hem at least three months prior to the start of your thesis (I did just before the summer vacations, starting my thesis on September).

Your supervisors are generally PhDs and their supervisors (professors) who are working on the same topic. You will have to sign a thesis contract before you start your thesis. This contract contains the starting date and finishing date of your thesis. It also contains the signatures of your supervisors and the study advisor assigned to you.

Tips from my Experience

In a thesis, you not only learn about your topic. You also about other important things like time and project management. If you can develop your scientific writing skills beforehand, it will be very helpful for you when you start a thesis. Learning how to use Microsoft Word properly can come in handy especially while writing your thesis proposal and final report. I have also attached a youtube link if you wish to learn a few tricks that can help you write reports in Word.

Stay tuned for more about a thesis in Wageningen in part 2 🙂

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Hi there, I come from Chennai, India. I joined Wageningen for my masters in September 2018 and I study Environmental Technology here. My journey has been incredible so far and I wish to share a few of my stories with you :-)

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There are 2 comments.

Hi Arun I’m Anjana I would like to do my masters in organic agriculture from WUR.can u plz tell about the scholarship and funding.

Hey my brother mam looking great. Help me push for masters biotech

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