Effect of l-cysteine on functional properties and fibrous structure formation of 3D-printed meat analogs from plant-based proteins

The development of three-dimensional (3D) printed meat analogs with fiber, texture, and sensory resembling meat remains challenging. This study investigated the effect of l-cysteine on functionality enhancement and fibrous structure formation in mixtures of mung bean protein isolate (MBPI) and wheat gluten (WG) for meat analog production. 3D printing was used to construct fibrous filaments. Raw MBPI-WG mixtures decreased rheological properties when increasing l-cysteine contents (0.0%-0.6%), promoting ink extrudability. The cys-0.4% ink exhibited the highest printing resolution and structural stability, correlated with its higher mechanical strength and increased disulfide cross-links. After cooking, the cys-0.4% sample showed a pronounced fibrousness in agreement with its microstructure image. This meat analog displayed a muscle-meat-like structure, improved texture, and reduced beany odor and bitter taste. Excessive cysteine contents (0.5%-0.6%) negatively affected the functionality of meat analogs. This study provides guidance for optimizing the amount of l-cysteine in meat analogs to improve product quality.

Effect of peptide formation during rapeseed fermentation on meat analogue structure and sensory properties at different pH conditions

This study aimed to modify the sensory properties of rapeseed protein concentrate using a combination of fermentation and high-moisture extrusion processing for producing meat analogues. The fermentation was carried out with Lactiplantibacillus plantarum and Weissella confusa strains, known for their flavour and structure-enhancing properties. Contrary to expectations, the sensory evaluation revealed that the fermentation induced bitterness and disrupted the fibrous structure formation ability due to the generation of short peptides. On the other hand, fermentation removed the intensive off-odour and flavour notes present in the native raw material. Several control treatments were produced to understand the reasons behind the hindered fibrous structure formation and induced bitterness. The results obtained from peptidomics, free amino ends, and solubility analyses strongly indicated that the proteins were hydrolysed by endoproteases activated during the fermentation process. Furthermore, it was suspected that the proteins and/or peptides formed complexes with other components, such as hydrolysis products of glucosinolates and polysaccharides.

Protein digestibility of textured wheat protein (TWP)-based meat analogs: (II) Effects of sodium tripolyphosphate

In this study, the effects of adding sodium tripolyphosphate during the extrusion of textured wheat protein (TWP)-based meat analogs were investigated. Five TWPs (TWP-C0, TWP-C0.10, TWP-C0.25, TWP-C0.50, and TWP-C0.75) were prepared with sodium tripolyphosphate concentrations of 0%, 0.10%, 0.25%, 0.50%, and 0.75%, respectively. The fibrous structure of TWPs was analyzed by determining their textural properties, degree of texturization, microstructure, and protein bonds. When the concentration of sodium tripolyphosphate increased from 0% to 0.75%, the fibers in TWPs became more regular and finer with smaller pores, the degree of texturization increased from 2.10 ± 0.09 to 2.73 ± 0.07, and the proportions of solubilized protein from the breaking of hydrophobic bonds and disulfide bonds increased from 2.06 ± 0.14% and 1.38 ± 0.11% to 3.42 ± 0.12% and 1.74 ± 0.05%, respectively. The results of particle size, soluble nitrogen content, and free amino acids of samples during digestion indicated that the disintegration rate and protein digestibility of TWPs increased with the increase in the concentration of sodium tripolyphosphate. After gastrointestinal digestion, the total free amino acids released in TWP-C0, TWP-C0.10, TWP-C0.25, TWP-C0.50, and TWP-C0.75 were 391.5 ± 2.2, 403.9 ± 1.5, 430.0 ± 3.6, 473.8 ± 2.9 and 485.3 ± 5.73 mg/10 g digesta, respectively. Sodium tripolyphosphate may improve the protein digestibility of TWPs by forming a finer fibrous structure with a more unfolded protein structure and more hydrophobic groups being exposed to enzymes.

Algorithm to determine orientation distribution function from microscopic images of fibrous networks: Validation with X-ray microtomography

Quantitative analysis of fibre orientation in a random fibrous network (RFN) is important to understand their microstructure, properties and performance. 2D fibre orientation distribution presents an in-plane fibre orientation without any information on fibre orientation in thickness direction. This research introduces a fully parametric algorithm for computing 3D fibre orientation as thickness is important for high-density or thick fibrous networks. The algorithm is tested for 3 major classes of nonwoven fabrics called low- (L), medium- (M) and high-density (H) ones. H fabric density is 6-8 times larger than the L fabric density. M fabric density (traditional intermediate fabric density) is 3-4 times larger than the L fabric density. Voxel models of experimental nonwoven webs were generated by an X-ray micro-CT (µCT) system and evaluated with the algorithm. Statistical results showed that a fraction of fibres orientated along the thickness direction increases as fibre density grows. To validate the accuracy of findings, deterministic voxelated virtual fibrous structures, created using mathematical functions were used. This novel algorithm is able to produce a 3D orientation distribution function (ODF) for any RFN including, models of nonwovens produced with various manufacturing parameters, experimentally verified and validated with X-ray µCT. Also, it can compute 2D ODFs of various types of RFNs to evaluate 2D behaviour of fibrous structures. The obtained results are useful for applications in many fields including finite element analysis, computational fluid dynamics, additive manufacturing, etc.

Egg white protein addition induces protein aggregation and fibrous structure formation of textured wheat gluten

The effect of egg white protein addition on the fibrous structure and protein aggregation of textured wheat gluten (TWG) extrudates was investigated. The hardness, springiness, chewiness, and degree of texturization of TWG significantly increased with the addition of egg white protein. Analysis of morphological characteristics showed a positive effect of egg white protein on the formation of the fibrous structure of TWG. The results of size-exclusion high performance liquid chromatography (SE-HPLC) indicated that the egg white protein improved the degree of wheat gluten aggregation, and the analysis of the protein intermolecular forces proved that disulfide bonds were the main contributor to the cross-linking of protein. In addition, an increase in the β-sheets also indicated an increase in protein aggregation induced by egg white protein. The addition of egg white protein promoted protein interactions and improved the fibrous structure of TWG.

Biomechanical impact of the porous-fibrous tissue behaviour in the temporomandibular joint movements. An in silico approach

The movement of the temporomandibular joint (TMJ) is a function of its complex geometry and its interaction with the surrounding soft tissues. Owing to an increase in the prevalence of temporomandibular joint disorders (TMDs), many computational studies have attempted to characterize its biomechanical behaviour in the last 2 decades. However, most such studies are based on a single computational model that markedly simplifies the complex geometry and mechanical properties of the TMJ's soft tissues. The present study aims to computationally evaluate in a wider sample the importance of considering their complex anatomy and behaviour for simulating both damping and motion responses of this joint. Hence, 6 finite element models of healthy volunteers' TMJ were developed and subjected to both conditions in two different behavioural scenarios. In one, the soft tissues' behaviour was modelled by considering the porous-fibrous properties, whereas in the other case they were simplified assuming isotropic-hyperelastic response, as had been traditionally considered. The damping analysis, which mimic the conditions of an experimental test of the literature, consisted of applying two different compressive loads to the jaw. The motion analysis evaluated the condylar path during the mandible centric depression by the action of muscular forces. From the results of both analyses, the contact pressures, intra-articular fluid pressure, path features, and stress/strain values were compared using the porous-fibrous and isotropic-hyperelastic models. Besides the great differences observed between patients due patient-specific morphology, the porous-fibrous approach yielded results closer to the reference experimental values and to the outcomes of other computational studies of the literature. Our findings underscore, therefore, the importance of considering realistic joint geometries and porous-fibrous contribution in the computational modelling of the TMJ, but also in the design of further joint replacements or in the development of new biomaterials for this joint.

Evaluating the hierarchical, hygroscopic deformation of the Daucus carota umbel through structural characterization and mechanical analysis

Many physically immobile plants develop passive yet ingenious strategies for active seed dispersal through self-deformation in response to external stimuli, such as humidity. These hygroscopic deformations are usually driven by the internal heterogeneous architecture, which provides valuable, inspiring information for the development of novel actuating systems. The Daucus carota compound umbel is an interesting structure showing a distinct hygroscopic deformation that operates at hierarchical levels among these plants. Here, we investigate the structure of the primary and secondary rays of the umbel associated with their deformation through mechanical analyses. We reveal that through controlling both the cellulose microfibril angle (MFA) and lignification, the multi-level bending behavior of the umbel is achieved, which contributes to efficient seed protection and dispersal. The primary rays generally show more significant bending curvature changes than the secondary rays, and within each level, the outer rays exhibit a larger motion amplitude than the middle and inner rays. Mechanical testing and theoretical analysis support that adjusting the lignin content within the ray structure compensates for the effect of the small differences in cellulose MFA on its bending behavior, which contributes to the overall hygroscopic deformation. Findings also show that the primary outer ray can generate reaction forces that are more than 700 times its weight, which is higher than that for the pine cone scales. The new insights from this work are instructive for bioinspired designs of complex, self-deforming structures and devices. STATEMENT OF SIGNIFICANCE: The carrot (Daucus carota) compound umbels exhibit a unique hierarchical, hygroscopic deformation for seed dispersal among immobile plants. In this work, we elucidate that the multi-level bending behavior of the umbel is achieved through manipulating the cellulose microfibril angle (MFA) and lignification of the primary and secondary rays for the first time. We also discover that adjusting the degree of lignification compensates for the effect of small cellulose MFA differences on the bending behavior theoretically and experimentally. The primary outer rays deform in a highly efficient manner, in which reactions forces about more than 700 times its weight are generated. The findings presented are instructive for bioinspired designs of complex, self-deforming structures and devices.

Approach towards the porous fibrous structure of the periodontal ligament using micro-computerized tomography and finite element analysis

The periodontal ligament (PDL) is a porous and fibrous soft tissue situated around the tooth, which plays a key role in the transmission of loads from the tooth to the alveolar bone of the mandible. Although several studies have tried to characterize its mechanical properties, the behaviour of this tissue is not clear yet. In this study, a new simulation methodology based on a material model which considers the contribution of porous and fibrous structure with different material model formulations depending on the effort direction is proposed. The defined material model was characterized by a non-linear approximation of the porous fibrous matrix to experimental results obtained from samples of similar species and was validated by rigorous test simulations under tensile and compressive loads. The global PDL response was also validated using the parameters of the characterization in a finite element model of full human canine tooth obtained by micro-tomography. The results suggest that the porous contribution has high influence during compression because the bulk modulus of the material depends on the ability of interstitial fluid to drain. On the other hand, the collagen fibres running along the load direction are the main responsible of the ligament stiffness during tensile efforts. Thus, a material model with distinct responses depending of the load direction is proposed. Furthermore, the results suggest the importance of considering 3D finite element models based of the real morphology of human PDL for representing the irregular stress distribution caused by the coupling of complex material models and irregular morphologies.