NAPIC: Microbubbles stabilised by plant protein-polysaccharide complexes: from oral processing to rational design of sustainable food foams

One full scholarship is available in the School of Food Science and Nutrition in 2025/26. This scholarship is open to Home fee rated and International applicants and covers UK tuition fees plus a maintenance grant (&pound;19,237 in 2024/25) for full-time study. Please note that international applicants would have to pay the difference between Home and International student tuition fees.<br /> <br /> This fully funded PhD place provides an exciting opportunity to pursue postgraduate research in a range of fields relating to Food Science, Physical Chemistry and Material Science with an industry partner.

<p>Incorporating gas bubbles and creating foams is a powerful strategy to improve the nutritional and sensory attributes of food products. Foams help to reduce the calorific content and improve food nutritional quality by decreasing the amount of unhealthy saturated fat. With the increasing emphasis on environmental sustainability factors, there is a growing demand to design foams stabilised by plant proteins or to at least partially replace conventional animal protein foaming agents, such as whey proteins (WP) or egg white proteins (EWP), with plant-based alternatives.  The key challenge lies in the unique foam stabilising effectiveness of WP and, in particular, EWP. Even partial replacement with plant proteins presents significant technological challenges. There is strong evidence that production of plant proteins results in one- to two-orders lower greenhouse gas emissions compare to animal proteins. Therefore, designing plant protein-based foods is the only possible way to accelerate the transformation to a healthier, sustainable and equitable food system. However, achieving successful foam design with plant proteins remains a distant goal. Another key barrier to this transition is the mouthfeel unacceptability, which has two aspects (a) astringency, hypothesized to be associated with the failure of plant proteins to support oral lubrication, and (b) instability of bubbles under oral processing conditions involving high shear and mechanical pressure, which leads to greater oral surface adhesion rather than separation. One alternative approach to achieve lubrication benefits is to consider foaming with less pure plant proteins i.e. plant protein concentrates which inherently contain remnants of plant polysaccharides which simultaneously benefits from less processing and cost. We hypothesise that the polysaccharides may act as a lubricating agent by providing hydration lubrication simply by viscosity modification without sacrificing the appearance of ‘clean-label’ and offer a dual benefit of improving the stabilization of the foams via enhanced bubble surface coverage. However, the true mechanism of potentially achieving such mouthfeel enhancement and how interaction of these sustainable plant protein-polysaccharide-stabilised bubbles occurs with orally-relevant surfaces to form a mesoscopic bubble-enriched tribofilm remains elusive due to lack of in situ-opto-mechanical tools.</p> <p paraeid="{bc2f43e0-58dd-48b3-a4df-d444a4ed74a8}{223}" paraid="925174612">Informed by emerging viscoelastic multiscale lubrication theories, this PhD project within the National Alternative Protein Innovation Centre (NAPIC) aims to create the next generation of sustainable microbubble-filled foods with an unprecedented lubrication performance. To rationally design such lubricating plant protein-based sustainable foams, the underpinning mechanism of action needs to be elucidated first. Lubricity of such plant protein polysaccharide-based foams on soft compliant surfaces coated with saliva is poorly understood in terms of the physicochemical characteristics of their boundary tribofilm, and interfacial interactions. To probe this, we will employ novel experimental approaches, combining dynamic friction measurement using 3D tongue-like rough deformable surfaces with in situ high-speed fluorescence imaging of the bubble-enriched films and the interfacial film will be resolved using atomic force microscopy (AFM). The boundary lubrication performance at low speeds will be observed using a bespoke reciprocating tribometer that will be attached to a high-resolution fluorescence microscope (in the Wolfson imaging facility at Bragg Centre). The project will employ biomimetic surfaces of human oral tissues inspired by our work on 3D biomimetic tongue model emulating the topography of real human tongue with accurate spatial distribution of tongue papillae (hundreds-of-micron-scale features) obtained using soft lithography by coating with human saliva to achieve appropriate wettability modification and thickness of oral films. The mouth coating properties of the bubbles will be further quantified using quartz crystal microbalance with dissipation monitoring (QCM-D) to probe affinity of these bubbles coated by protein-polysaccharide to weakly polar surfaces representative of oral conditions. Combining theoretical models including surface deformation theories, we aim to validate that stable a tribofilm composed of sustainable  microbubbles are able to facilitate creamy-foamy mouthfeel. Overall, this PhD will contribute to new approaches of making sustainable foams by focusing on mouthfeel as a key benefit. </p> <p paraeid="{68ebe95d-9551-4600-aeeb-af9f974868d2}{131}" paraid="1012948632">In addition to the bulk of the experimental work carried out at Leeds, there will be also an exciting opportunity for the student to do a short placement at an industry R&D facility. The PhD student will get excellent opportunities to do placements with our industrial partners and the wider community in UK and abroad within NAPIC – please see the website for partners of NAPIC: <a aria-label="Link https://napic.ac.uk/partners/" href="https://napic.ac.uk/partners/" id="menurm75" rel="noreferrer noopener" target="_blank" title="https://napic.ac.uk/partners/">https://napic.ac.uk/partners</a>.</p> <p paraeid="{68ebe95d-9551-4600-aeeb-af9f974868d2}{131}" paraid="1012948632"><strong>Information about the Award</strong></p> <ul> <li paraeid="{68ebe95d-9551-4600-aeeb-af9f974868d2}{131}" paraid="1012948632">We are offering 1 full-time PhD scholarship in the School of Food Science and Nutrition covering UK tuition fees and maintenance grant (£19,237 in 2024/25) for 3.5 years, subject to satisfactory progress. <strong>Please note that international applicants are welcome to apply but would need to cover the difference between UK and International tuition fees. The maintenance stipend is paid monthly and cannot be used to pay your fees. You can read more about research degree fees <a href="https://www.leeds.ac.uk/research-fees/doc/research-degrees-fees">here</a>.</strong></li> </ul> <p><strong>Duration of the Award</strong></p> <ul> <li>Full-time (3.5 years).  The award will be made for one year in the first instance and renewable for a further period of up to three years, subject to satisfactory academic progress.</li> </ul> <p><strong>Other Conditions</strong></p> <ul> <li>Applicants must not have already been awarded or be currently studying for a doctoral degree.</li> <li>Awards must be taken up by 1^st October 2025.</li> <li>Applicants must live within a reasonable distance of the University of Leeds whilst in receipt of this scholarship.</li> </ul>

<p>Formal applications for research degree study should be made online through the <a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University's website</a>. You will need to create a login ID with a username and PIN.</p> <ul> <li>For ‘Application type’ please select ‘Research Degrees – Research Postgraduate’.</li> <li>The admission year for this project is 2025/26 Academic Year.</li> <li>For ‘Planned Course of Study’ please select ‘PhD Food Science and Nutrition Full-time’.</li> <li>For ‘Proposed Start Date of Research’ please select 1 October 2025.</li> <li><strong>In the research information section, you must state clearly that the project you wish to be considered for is ‘NAPIC: Microbubbles stabilised by plant protein-polysaccharide complexes: from oral processing to rational design of sustainable food foams’ and name <a href="https://environment.leeds.ac.uk/food-nutrition/staff/7151/professor-anwesha-sarkar">Professor Anwesha Sarkar</a> as your proposed supervisor. If you do not do this, your application may not be considered.</strong></li> </ul> <p>If English is not your first language, you must provide evidence that you meet the University'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. Across all Faculties 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. Applicants will always be selected based on merit and ability.</em></p>

Applicants to this scholarship in the School of Food Science and Nutrition are expected to hold a bachelor degree in a relevant subject (2.1 or above or equivalent) or a good honours degree together with a Masters degree. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the Postgraduate Research Admissions team prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.5 overall with at least 6.0 in each component (reading, writing, listening and speaking) or equivalent. 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 further information please contact Prof Anwesha Sarkar (<a href="mailto:A.Sarkar@leeds.ac.uk" rel="noreferrer noopener" target="_blank">A.Sarkar@leeds.ac.uk</a>).</p>