Impact of processing conditions on the multiscale structure of high moisture extrudates of plant proteins as seen by multi-modal imaging

Impact of processing conditions on the multiscale structure of high moisture extrudates of plant proteins as seen by multi-modal imaging

 

Camilla Terenzi^1,*, Sam Kuijpers¹, Ekaterina D. Garina², Martijn Gobes¹, Wim Bouwman², Johannes Hohlbein¹, John P.M. van Duynhoven^1,3

¹ Laboratory of Biophysics, Wageningen University and Research, Wageningen, The Netherlands

²Department of Radiation Science and Technology, Delft University of Technology, Delft, The Netherlands

³Unilever Global Foods Innovation Centre, Wageningen, The Netherlands

*camilla.terenzi@wur.nl

 

Protein-rich foods originating from animals are the major contributor to the environmental impact of food. This has made it necessary to explore alternative, plant-based, protein- and nutrient-rich food solutions, e.g. based on soy ingredients. High-moisture extrusion (HME), which involves cooling of a hot protein melt in the presence of shear and temperature gradients, has become an established approach for converting proteins and polysaccharides into phase-separated fibrous structures used in the industrial production of meat analogues with animal meat-like texture¹. The latter is considered as a key success factor for consumer appreciation of those products. Yet, currently exploited imaging, spectroscopic or mechanical methods fail providing, ex situ or in situ, a robust, unified, quantitative and multi-scale, characterization of the correlation between hierarchical macro-/micro-structure of the final products, and the synergistic/competitive protein network modifications, namely phase separation and denaturation/re-assembly, upon extrusion processing.¹

This talk will present recent multi-modal methodological advances in the multiscale measurement of process–structure–function relationships of plant-based soy protein extrudates, with primary focus on the dependence of anisotropic structure formation upon inline pH shifting before  HME. Results from conventional analysis techniques, e.g. based on laser anisotropy index (AI) measurements and hardness testing of extrudates, will be compared with the characterization of extrudates and deadstop samples provided by non-invasive, spatially-resolved, and in-situ-translatable advanced NMR and MRI methods. Stemming from the necessary quantification of phase-separated protein- and water-rich domains by means of spatially-unresolved ¹H time-domain NMR (TD-NMR) in soy protein concentrates (SPCs),² the performance of T₂-weighted, Diffusion Tensor Imaging (DTI), and Chemical Exchange Saturation Transfer (CEST) mapping for probing molecular-to-macroscopic-level details of the anisotropic structure formation is shown. By means of advanced image analysis approaches, based on Fourier Transform and optimized on super-resolution optical imaging data, spatially resolved MRI information about fiber alignment can be quantitatively unveiled by means of the structural order parameter and DTI fractional anisotropy maps. NMR/MRI results are also compared with the respective nano-scale information provided from Small-Angle-Scattering (SAS) of neutrons and X-rays.³

Future perspectives regarding the translatability of the proposed ex situ methods to in situ applications, including other protein products such as dairy, will be discussed.

 

Acknowledgments: NWO OTP-TTW program and “Measurement and Modelling of Multiscale Processed Protein Products” (MP3) project (18744). The uNMR-NL Grid: “A distributed, state-of-the-art Magnetic Resonance facility for the Netherlands” (NWO grant 184.035.002).

 

 

References:

1. Ruud van der Sman & Atze-Jan van der Goot. Current Res. Food Sci., 6 100510 (2023).
2. Sam Kuijpers; et al. In preparation for Food Res. Intern.
3. Ekaterina D. Garina; et al. Food Hydrocoll. In press (2024).