2017 - 2021
This PhD thesis describes the effect of mild aqueous fractionation processes on the functionality of pea protein, in terms of molecular and microstructural characteristics. The thesis is structured according to the type of model foods studied. The first part focuses on pea protein dispersions and gels. The second part reports on the stabilization of oil and air after incorporation in foams, emulsions, and emulsion-filled gels. The third part addresses hybrid plant-dairy protein dispersions and gels. The results from this research led to the realization that fractionation can be tailored to specific pea protein functionality.
2018 - 2021
Pea protein is a promising protein for meat-replacing products. In the high temperature shear cell, pea protein can be used to form fibrous structures in a blend with components like gluten or pectin, yielding similar textural properties as chicken; even though the elasticity is not yet the same. This thesis provided new insights into structure formation, especially by investigating the non-linear rheology at conditions that are directly relevant to thermomechanical processing, and compare the properties obtained with PPI, to other materials, such as SPI-based blends and meat. Heating at high temperature induces elasticity in the proteins during structuring, but the extent of this effect depended on the actual protein source. These insights will be important for further development of even better plant-based meat analogues, using more advanced formulations that will give the best possible consumer experience.
The juiciness of meat and meat analogue products is related to their ability to bind and release water. In this thesis, the hydration properties of plant protein gels and meat analogues produced with Shear Cell technology were studied using Flory-Rehner theory. This revealed that meat analogue structure plays an important role in both water binding and water release.
Patricia Duque Estrada
Meat analogues can help consumers to switch to a more plant-based diet. In this thesis, routes are investigated to include iron supplementation to meat analogues. Iron, though, can enhance protein and lipid oxidation. Therefore methods are developed to quantify the effect of iron addition and process conditions on the oxidative stability of (soy-based) ingredients and meat analogue products. It was found that oxidation plays a role, but oxidation levels found were within range reported for processed meat products.
Zhoajun (Fiona) Wang
This thesis describes the structure formation process of calcium caseinate in great detail. It revealed a number of important factors that govern fibrous structure formation and the resulting material properties. An unexpected finding was the importance of air (bubbles) as structure forming phase in protein dispersions. Besides, the importance of the how the calcium caseinate was dried when making the ingredient was demonstrated and explained.
Oil production from sun flower kernels lead to a large by-product stream that has potential to be used in human food application. Main barrier is the presence of high levels of phenolic compounds that give bitter taste and colour formation when interacting with proteins. This thesis provides new insights in mechanisms behind the complexation and how to mitigate effects when processing sun flower kernels.
This thesis describes the application of shear cell technology to make fibrous materials using soy protein isolate as main ingredient. The mechanical properties of the formed materials were successfully linked to their microstructure. Further, methods were developed to study the rheology of dense protein blends at high temperature. The thesis ends with a review of structuring technologies for current and future meat analogues.
In this thesis, a novel approach for the fractionation of plant materials is studied for pea and soy. Focus in not on purity, but on functionality. It was shown that partial or mild fractionation could be used to create protein-enriched ingredients with good functionality. An exergy analysis revealed that partial fractionation is a promising route to make food ingredients in a more sustainable manner.
Angelica Tamayo Tenorio
Leaves from sugar beets are produced in large quantities, but so far not used in foods. An interesting route for better utilizing sugar beet leaves is the extraction of the proteins, which can be used as food ingredients. In this thesis, route for total protein use are explored, the functional properties are characterized and conceptual process designs are evaluated. The thesis ends with discussing similarities and differences between protein extraction from conventional and herbaceous biomass, like sugar beet leaves.
Water binding by protein gels and particles is a very important food property. Here, the use of time domain NMR has been shown to be powerful tool to study water-protein interactions. Results were interpreted using Flory-Rehner theory. Whey protein was taken as model material, which properties were selectively changed though for example crosslinking. In the final chapter, proteinaceous dispersions of pea, soy and lupine were analyzed using the developed methodology and outcomes were compared with results obtained for whey.
This thesis bridges the science fields of exergy and food engineering. In this thesis, two industrial cases are studied in great detail, being the industrial bread and mushroom production. The cases were used to improve the method of exergy analysis. The outcomes were generalized in a number of rules to improve sustainability of current food processes through the use of so called “system archetypes”. One outcome that clearly stood out was the importance of avoiding waste and fully use of starting materials.
Laura van Donkelaar
Brewers spend grain is a major by-product from beer industry, which is produced in massive quantities. To reduce this by- product stream, it was investigated whether it is possible to remove the components forming the brewer spent grain before the actual brewing process. Barley was pearled to remove the hull, after which the remaining enzyme activity was tested. It turned out that pearling reduced the byproduct stream, but the remaining barley kernel still contained sufficient biological activity to allow use in a beer brewing.
Lupin is a potential new crop to provide protein-rich ingredients that can be used in novel food applications like meat analogues. To make such use possible, it is necessary to develop novel and efficient fractionation processes. In this thesis, the effect of complete and partial fractionation on the functional properties of lupin are described. The efficiencies of both processes are investigated using exergy analysis. The thesis ends with describing possible novel food applications for protein-rich ingredients derived from lupine.
Enzyme-assisted separation and hydrolysis of gluten
In this thesis the work of Elsbeth van der Zalm is continued and extended. Previously, it was shown that starch and gluten could be separated from wheat flour through shear induced separation. Key element was a high dry matter content. In this thesis, it is shown that hydrolysis of components like gluten and arabinoxylanes can also take place using high dry matte content. Combining those two research leads creates many new options for processes that aim at separation and hydrolysis of biomaterials.
Separation of isoflavones from okara
Okara is a by-product from the soy-milk industry. It is created when making milk from soy beans, and is currently not used for food applications. It contains a lot of valuable components including phenolic compounds, called isoflavones. In this thesis, it has been studied how isoflavones can be extracted from okara using a broad range of solvents. Besides, the potential of the use of solid adsorbents is explored. All insights are captured in a novel processing concept, of which the sustainability effects were studied using exergy analysis.
Towards sustainable fish feed production using novel protein sources
A route to make fish feed more sustainable is to replace fish meal by plant-based ingredients in fish feed pellets. It requires careful balancing of the nutritional profile and managing the differences in functional properties of fish meal compared to plant-based ingredients. Plant-based ingredients that have a low gelling capacity, such as lupine, turned out to be the most promising candidates for replacing fish meal. The effect of replacing fish meal has been studied using exergy analysis, in which the effect of eco-exergy was included.
Structuring high protein foods
Increase protein consumption by certain groups of consumers is thought to give rise to positive health effects such as improved body weight control and reduced chance of sarcopenia. However, protein rich foods are generally not attractive to eat. Here, an scientific review is given for possible causes and possible solutions are suggested. Experimentally, the effect of pre-gelation of part of the whey protein is studied to make high protein food products more attractive.
Elsbeth van der Zalm
Concentrated separation of wheat flour into starch and gluten
This thesis investigates a novel process principle for the separation of starch and gluten from wheat flour. It builds on a discovery made by Seyed Hadi Peighambardoust. Starch and gluten can be separated using high dry matter contents of up to 60 wt% using the concept of shear induced separation. This application of this process industrially will not only lead to major water and energy savings, but it also delivers wheat gluten with significantly better functional properties.
Lieke van Riemsdijk
The formation and deformation of protein structures with visco-elastic properties
This thesis describes a novel route to make gluten-free bread. Starting point of the work is the hypothesis that gluten functional properties result from the fact that gluten forms colloidal particles when mixed with water. Therefore, colloidal whey protein particles were produced and the resulting rheological properties were studied. In the second part of the thesis, the colloidal particles were used in model mixtures to make gluten-free dough and bread.
Edwin A. Habeych
Development of starch based materials
In the first part of the thesis, a model is presented to predict that gelatinization temperature of starch in mixtures of water and glucose. Then the structuring of starch when mixed with zein was studied using a next variant of the conical shearing device. It was clearly demonstrated that non-compatibility was an important factor during structuring. The use of fermented rice bran was demonstrated as interesting route to enhance interactions between starch and zein, leading to stronger materials.
Meat has a hierarchical structure, which means that large meat fibers consists of smaller fibrils. To precisely mimic such structure, it is important to be able to make nanofibrils. This thesis builds on previous work and revealed that conditions to make whey fibrils can also be used to make similar fibrils from soy proteins. Key finding in this thesis was that fibrils can be formed from proteins only after selective hydrolysis. Oligomers resulting from that hydrolysis turned out to be the building blocks of the nanofibril.
Flow-induced structuring of dense protein dispersions
This project investigate the potential of using enzymatic gelation under deformation to create novel food structures in protein-fat-water dispersions. The effect of the dispersed (fat) phase was investigated and the effect of changing processing steps on the resulted structure and rheological properties was quantified. In this project, it was discovered that the application of well-defined shear flow as applied by the shear cell could led to highly fibrous proteinaceous materials.
Seyed Hadi Peighambardoust
The first step in making bread is the creation of a good dough. A dough is normally produced using a mixing device, such as Farinograph. Here, dough was studied while being processed in shearing devices, both the conical shear cell and a couette device. Main finding was that dough becomes process tolerant when processed in a shearing device. The presence of elongational flow is probably responsible for dough weakening in regular dough mixers.
Mark van der Veen
A route to reduce energy and water consumption in food processes is to increase dry matter contents of materials being processed. This thesis describes research on dense starch dispersions. First the potential of microwave heating to sterilize starch powder was studied. Then, the hydrolysis of starch under extreme low water content is described. It was found that enzymatic hydrolysis was successful and that the effect of shear on enzyme activity was limited under those conditions.
René van de Einde
This project forms the basis for the research using shearing devices. Those devices were developed to better quantify the effect of thermo-mechanical processing on changes in dense biopolymer systems. Here, the thermomechanical breakdown of starch was studied. The torque-values as recorded by the shearing device could be connected to molecular properties of starch using a simple force-balance model. The thesis ends with a review of starch processing.