TD-NMR Structural Profiling of Meat and Plant-Based Meat Analog Burgers

Abstract

The functional properties of food are closely linked to its atomic, molecular, and microstructural characteristics. This study evaluates the potential of time-domain nuclear magnetic resonance (TD-NMR) relaxometry as a non-destructive technique for profiling the internal microstructure of Soy-based plant-based meat analogs (PBMA) compared to Angus beef burgers. TD-NMR results were supported by measurements of water content, water release, and morphological analysis using visual and confocal microscopy. Microscopy revealed clear structural differences: Soy-PBMA burgers exhibited a gel-like, porous matrix, while Angus beef burgers showed compact, fibrous bundles characteristic of natural muscle tissue. Moisture analysis indicated lower total water content in Soy burgers, while water release tests demonstrated higher water-holding capacity in Angus burgers, suggesting stronger protein-water interactions. TD-NMR relaxation data reflected these structural distinctions. T₁ recovery times were longer in Angus burgers, while T₂ relaxation times were shorter and more narrowly distributed, consistent with tightly packed myofibrillar proteins. In contrast, Soy-PBMA burgers exhibited broader T₂ distributions, reflecting a looser, more porous plant-protein matrix. One-dimensional (1D) and two-dimensional (2D) T₁-T₂ spectral fingerprinting further highlighted differences in proton relaxation behavior, particularly between the myofibrillar proteins of meat and the globular proteins of plant-based formulations. These findings confirm TD-NMR relaxometry as a rapid, reliable, and non-destructive method for differentiating the internal structure of meat and plant-based products. This approach offers valuable insights for product development, quality assurance, and the design of next-generation plant-based meat alternatives.

Keywords: TD‐NMR relaxation; food quality control; meat burger; plant‐based meat analogs; structural analysis.

FIGURE 1

Comparison of fifteen replicates of TD‐NMR measurements showing 1D T₁ recovery curves (top) and T₂ decay curves (bottom) for Angus meat and Soy‐PBMA burger samples. A zoomed‐in view of the most relevant time interval (up to 500 ms) is included in each graph to highlight the early‐phase relaxation behavior.

SCHEME 1

Visual appearance and main structural components of Angus meat and Soy‐PBMA burgers. The Angus meat burger consists of fibrous proteins, structural polymeric collagen polypeptides, water (H₂O), saturated triacylglycerols (TAGs), salt, and spices. The Soy‐PBMA burger contains globular plant proteins, structural polymeric plant cellulose and methyl cellulose fibers, water (H₂O), unsaturated TAGs, salt, and flavorings. Images were obtained specifically for this study at PLBL.

FIGURE 2

Representative 1D T₁ recovery spectra of Angus meat and Soy‐PBMA burgers. These typical recovery profiles were selected from a database comprising 64 replicates. The main T₁ peak for the Angus meat burger appears at 502 ms, accounting for approximately 70% of the total signal intensity. In contrast, the Soy‐PBMA burger exhibits two major T₁ peaks: one at 99 ms (40%) and another at 259 ms (39%), reflecting the heterogeneous relaxation behavior of its plant‐based components.

FIGURE 3

Representative 1D T₂ decay spectra of Angus meat and Soy‐PBMA burgers. These typical decay profiles were selected from a comprehensive database comprising 64 replicates. The main T₂ peak for the Angus meat burger appears at 45 ms and constitutes approximately 81% of the total signal intensity. In contrast, the Soy‐PBMA burger exhibits three major T₂ peaks at 22 ms (20%), 66 ms (35%), and 144 ms (20%), reflecting a more with its plant‐based components.

FIGURE 4

Comparison of 2D T₁‐T₂ relaxation fingerprints of main components in Angus meat and Soy‐PBMA burgers. Thirty samples from each burger type were analyzed. Three major component groups—proteins, oils, and structural polymers—are identified. Albumin and soybean protein isolate spikes were used to locate Soy‐PBMA globular proteins. Mapping of Soy and Angus oils is based on the characteristic T₁ = T₂ diagonal. Plant cellulosic and starch structural polymers in Soy‐PBMA and collagen structural polymers in Angus meat were assigned based on their size and rigidity.

FIGURE 5

Confocal laser scanning microscopy (CLSM) images of Angus meat and Soy‐PBMA burger samples. The Angus meat burger exhibits an aggregated, bundle‐like structure with a broad distribution of spherical particle sizes. In contrast, the Soy‐PBMA burger displays a well‐dispersed pattern of emulsified spherical vesicles with varying sizes. Samples were diluted 1:10 and imaged at 63× magnification using super‐resolution CLSM to highlight microstructural differences between the two burger types.