PETRA III Science Seminar | Exploring non-equilibrium nanoscale processes and spatio-temporal scaling laws in a heated egg yolk using coherent X-rays

by Nimmi das Anthuparambil (FS-PETRA-S (FS-PET-S Fachgruppe P10))

Tuesday 19 Sept 2023, 14:15 → 15:00 Europe/Berlin

Online

Nimmi Das Anthuparambil^1,2, Anita Girelli³, Sonja Timmermann², Marvin Kowalski²,
Mohammad Sayed Akhundzadeh², Sebastian Retzbach³, Maximilian D. Senft³, Michelle
Dargasz², Dennis Gutmüller³, Anusha Hiremath³, Marc Moron⁴, Özgül Öztürk²,
Hanna-Friederike Poggemann³, Anastasia Ragulskaya³, Nafisa Begam³, Amir Tosson²,
Michael Paulus⁴, Fabian Westermeier¹, Fajun Zhang³, Frank Schreiber³, Michael
Sprung¹, Christian Gutt²

¹Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
²Department Physik, Universität Siegen, 57072 Siegen, Germany.
³Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany.
⁴Fakultät Physik/DELTA, Technische Universität Dortmund, 44221 Dortmund, Germany.

Email: nimmi.das.anthuparambil@desy.de

Egg yolk is widely utilized as a culinary component due to its high nutritious value and excellent emulsifying and gelling abilities [1,2]. When heated, it undergoes a solutionto-gel transition. It is known that the texture and visco-elastic properties of the final gel are a result of the high concentration and diversity of proteins and lipids found in the yolk [2]. Despite its versatile use in the food industry [1,2] and pharmaceuticals [3], a little is known about the functional contribution of its constituents to the final gel microstructure. Using low-dose X-ray photon correlation spectroscopy [4] in ultra-small angle X-ray scattering geometry, we follow the time-resolved structural and dynamical evolution of multiple non-equilibrium processes occurring in a heated hen egg yolk. Following key structural and dynamical features, we identify non-equilibrium processes such as denaturation and aggregation of proteins, protein gelation, gel ageing, two-step aggregation of yolk low-density lipoproteins (LDLs), and gelation of yolk granules for wide time-temperature combinations. We find that the overall kinetics and dynamics governing protein denaturation, aggregation, and gelation follow Arrhenius-type time-temperature superposition (TTS). This implies an identical mechanism underlying these consecutive processes, with a temperature-dependent reaction rate. At high temperatures, TTS breaks down during gelation and temperature-independent gelation dynamics is observed. This indeed reflects the complex association of protein aggregates that results in a gel network. Furthermore, the two-step complex aggregation of LDLs contributes to the grainy microstructure of the yolk. Consolidating the evidence we create a time-temperature phase diagram that delivers a wealth of information about the physics of nanoscale processes occurring in an egg yolk during cooking. In a broader sense, our research provides an illustration of how to comprehend the fascinating non-equilibrium events in inherently complex, multi-component, thermally driven biological systems on length scales ranging from nanometers to micrometers in a time spectrum of milli-seconds to hours.

[1] M. Anton et al., J. Sci. Food Agric. 93, 2871–2880 (2013).
[2] Y. Zhao et al., Food Chem. 355, 129569 (2021).
[3] L. Gu et al., Food Sci. Biotechnol. 32, 121133 (2023).
[4] F. Perakis, and C. Gutt, Phys. Chem. Chem. Phys. 22, 19443 - 19453 (2020).