Mildly refined fractions of legumes as novel sustainable food ingredients

Summary<br /> Food components, such as starch and other biopolymers and macromolecules (proteins), are being used in the food industry as thickeners, gelling agents, or emulsifiers in a variety of products. Plant-based proteins with high functionality with respect to the stabilization of multiphase systems are needed. There are many existing modification methods used to modulate plant proteins, which generally use harsh fractionation conditions, such as the use of water, corrosive chemicals or high physical stresses. This project will aim to investigate dry fractionation via milling and air classification as a milder and more sustainable processes in which protein functionality can be retained. The fractions will then be processed via electrospraying to produce particles of 200-1000 nm range . Electrospraying, is an emerging technology used to produce dried particles and shows great advantages over conventional spraying systems because it does not require heat and therefore consumes less energy.<br />

<p><strong>Background</strong></p> <p>Food components, such as starch and other biopolymers and macromolecules (proteins), are being used in the food industry as thickeners, gelling agents, or emulsifiers&nbsp;in a variety of products, including sauces, dressings, and ice-creams. The texture and stability of these products depend on the structure and function relationship of the added ingredients.&nbsp;&nbsp;</p> <p>The use of a wide range of plant protein sources in food formulation has raised a remarkable attention during the last decade. It is now clearly advocated that rebalancing diets by increasing the proportion of plant-based proteins, in so-called flexitarian diets, will be among the only options to achieve a sustainable global food system, combined with a substantial reduction of food waste.&nbsp;Some of the challenges faced in using plant proteins as emulsifiers or food ingredients result from the techniques used to isolate plant proteins from raw material (e.g.&nbsp;peas or pea flour) compared to those used to isolate animal proteins that affect the techno-functional properties such as solubility,&nbsp;texture&nbsp;and mouthfeel. Many plant proteins have poor solubility in water.</p> <p>Plant-based proteins with high functionality with respect to the stabilization of multiphase systems, such as foams and&nbsp;emulsions&nbsp;are needed.&nbsp;There are many existing modification methods used to modulate plant proteins. Most of the&nbsp;extraction&nbsp;methods&nbsp;generally&nbsp;use&nbsp;harsh fractionation conditions, such as the use of water, corrosive chemicals or high physical stresses. During the extraction process, the protein fractions are separated from the plant cell&rsquo;s oil, fibre or starch components employing wet treatment depending on the initial raw material properties. Wet decantation and isoelectric precipitation are used for oilseeds or membrane proteins extracted from green leaves, which leads to relatively pure protein isolate. The current generation of meat alternatives are produced from protein-rich ingredients obtained from such extraction procedures.</p> <p><strong>Aims and objectives</strong></p> <p>This project will aim to investigate dry fractionation&nbsp;via milling and air classification as a milder and more sustainable processes in which protein functionality can be retained.&nbsp;This involves the fine milling of the grains during which starch fragments are released from a protein matrix that break up into small fragments. This step follows an air classification process, during which the protein fragments are separated by the starch granules on the basis on their size. A protein concentrate is then obtained with 50 g protein/100 g of dry matter and a starch concentrate is obtained with up to 67 g starch/100 g of dry matter. It is hypothesized that both these fractions&#39; recovery, characterization, and gleaned understanding of the structure-fucntion relationships will underpin future applications and a more sustainable food production.&nbsp;</p> <p>The fractions will then be processed via electrospraying to produce particles of 200-1000 nm range. Electrospraying, is an emerging technology used to produce dried particles and shows great advantages over conventional spraying systems because it does not require heat and therefore consumes less energy. An electrical potential is created between the polymer solution or emulsion and a grounded collector, leading to a spray of particles. The particle sizes produced are much smaller than via other techniques, down to the nano-scale and with a more narrow size distribution (i.e., less aggregated) facilitating their solubility and functional properties.</p> <p>This PhD project will seek to develop this low carbon footprint fractionation process for legumes such as pea,&nbsp;fava&nbsp;bean, and lentil.&nbsp;The composition (fibre, protein and starch) of the produced fractions will be determined using a range of multi-scale techniques.&nbsp;Differential scanning calorimetry (DSC) will be used to measure the protein denaturation temperature and the starch gelatinization temperature for the grains, legumes, flour and the present fractions. Asymmetric flow field flow fractionation (AF4) with multidetection (DRI, MALS, UV-VIS) will enable to characterize the molecular weight distribution of the protein and polysaccharide fractions. The viscoelastic properties of the fractions in solution will be measured using small deformation rheology and&nbsp;the contact angle and interfacial tension will be measured by a tensiometer. Other biophysical properties, including size,&nbsp;structure, solubility, and zeta-potential, will be&nbsp;evaluated.&nbsp;For the first time, small angle X-ray scattering (SAXS) will be used to investigate the internal nanostructure and crystallinity of starch and proteins&nbsp;of the the ocurring fractions.&nbsp;The morphology of the obtained particles will be probed by microscopy (optical, scanning electron microscope) will be used, while their chemical structure will be characterized using Fourier-transform infrared spectroscopy (FT-IR), while their functional properties will be compared with the conventional powders.</p>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University&#39;s website</a>. Please state clearly in the research information section&nbsp;that the research degree you wish to be considered for is&nbsp;<strong>Mildly refined fractions of legumes as novel sustainable food ingredients</strong><strong>&nbsp;</strong>&nbsp;&nbsp;as well as&nbsp; <a href="https://environment.leeds.ac.uk/faculty/staff/9827/dr-evi-paximada">Dr. Evi Paximada</a> as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education.&nbsp;Within the School of Food Science we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+; and people with disabilities.&nbsp;Applicants will always be selected based on merit and ability.</em></p>

Applicants to research degree programmes in the School of Food Science and Nutrition should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline, or a good honours degree together with a Masters degree.<br /> The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study in the School of Food Science and Nutrition is:<br /> - IELTS - an overall band of 6.5 with no individual skill band below 6.0 in all components<br /> - iBT TOEFL - (Internet-based Test of English as a Foreign Language): a score of 92 overall with Listening 21; Reading 21; Speaking 23; Writing 22.<br /> <br /> The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<p>For queries regarding the project, please contact <a href="mailto:E.Paximada@leeds.ac.uk">Dr. Evi Paximada</a></p> <p>Any enquiries about the application procedure can be sent to the Graduate School Office admissions team<br /> e:&nbsp;<a href="mailto:EMAIL@leeds.ac.uk">maps.pgr.admissions@leeds.ac.uk</a></p>