Water release kinetics from soy protein gels and meat analogues as studied with confined compression

Binary Pea Protein-Psyllium Hydrogel: Insights into the Influence of pH and Ionic Strength on the Physical Stability and Mechanical Characteristics

Food hydrogels, used as delivery systems for bioactive compounds, can be formulated with various food-grade biopolymers. Their industrial utility is largely determined by their physicochemical properties. However, comprehensive data on the properties of pea protein-psyllium binary hydrogels under different pH and ionic strength conditions are limited. The aim of this research was to evaluate the impact of pH (adjusted to 7, 4.5, and 3) and ionic strength (modified by NaCl addition to 0.15 and 0.3 M) on the physical stability, color, texture, microrheological, and viscoelastic properties of these hydrogels. Color differences were most noticeable at lower pH levels. Inducing hydrogels at pH 7 (with or without NaCl) and pH 4.5 and 3 (without NaCl) resulted in complete gel structures with low stability, low elastic and storage moduli, and low complex viscosity, making them easily spreadable. Lower pH inductions (4.5 and 3) in the absence of NaCl resulted in hydrogels with shorter linear viscoelastic regions. Hydrogels induced at pH 4.5 and 3 with NaCl had high structural stability, high G' and G" moduli, complex viscosity, and high spreadability. Among the tested induction conditions, pH 3 with 0.3 M NaCl allowed for obtaining a hydrogel with the highest elastic and storage moduli values. Adjusting pH and ionic strength during hydrogel induction allows for modifying and tailoring their properties for specific industrial applications.

The Potential of Soluble Proteins in High-Moisture Soy Protein-Gluten Extrudates Preparation

In this study, the effects of different soluble proteins, including collagen peptides (CP), soy protein hydrolysate (HSPI), whey protein isolate (WPI), sodium caseinate (SC), and egg white protein (EWP), on the structural and mechanical properties of blends containing soy protein isolate (SPI) and wheat gluten (WG) were investigated using high-moisture extrusion. The addition of CP and HSPI resulted in a more pronounced fibrous structure with increased voids, attributing to their plasticizing effect that enhanced polymer chain mobility and reduced viscosity. WPI, SC, and EWP acted as crosslinking agents, causing early crosslink formation and decreased polymer chain mobility. These structural variations directly influenced the tensile properties of the extrudates, with CP displaying the highest anisotropic index. Moreover, the presence of soluble proteins impacts the permeability of the extrudates. These insights shed light on how soluble proteins can be used to modify the properties of SPI-WG blends, making them suitable for meat analogue production.

Effect of Process Variables and Ingredients on Controlled Protein Network Creation in High-Moisture Plant-Based Meat Alternatives

The market has observed a rapid increase in the demand for plant-based foods as an alternative to animal meat products. Technologies such as high-moisture extrusion (HME) have the potential to develop anisotropic structures using alternative protein ingredients. This article discusses the different possible mechanisms responsible for structure formation and the effect of extrusion process parameters and outlines the recent advances in the long cooling dies (LCDs) used for meat alternative development. The role of different protein ingredients and the impact of combining them with other biopolymers were also evaluated. The underlying mechanism behind anisotropic structure formation during HME is a synergistic effect, with substantial dependence on the source of ingredients and their processing background. Formulation including proteins derived from plants, insects, animals, and microalgae with other biopolymers could pave the way to develop structured meat alternatives and fill nutritional interstices. Dynamic or rotating annular gap cooling dies operating at freely controllable shear and static annular gap dies are recent developments and assist to produce layered or fibrous structures. The complex chemical sites created during the HME of plant protein favour flavour and colour retention. This paper summarises the recent information published in the scientific literature and patents, which could further help researchers to fill the present knowledge gaps.

Hypotheses concerning structuring of extruded meat analogs

In this paper, we review the physicochemical phenomena occurring during the structuring processes in the manufacturing of plant-based meat analogs via high-moisture-extrusion (HME). After the initial discussion on the input materials, we discuss the hypotheses behind the physics of the functional tasks that can be defined for HME. For these hypotheses, we have taken a broader view than only the scientific literature on plant-based meat analogs but incorporated also literature from soft matter physics and patent literature. Many of these hypotheses remain to be proven. Hence, we hope that this overview will inspire researchers to fill the still-open knowledge gaps concerning the multiscale structure of meat analogs.

Effect of Wheat Gluten and Peanut Protein Ratio on the Moisture Distribution and Textural Quality of High-Moisture Extruded Meat Analogs from an Extruder Response Perspective

Wheat gluten (WG) and peanut protein powder (PPP) mixtures were extruded at high moisture to investigate the potential application of this mixture in meat analog production. Multiple factors, including the water absorption index (WAI), water solubility index (WSI), rheological properties of the mixed raw materials, die pressure, torque and specific mechanical energy (SME) during high moisture extrusion, texture properties, color, water distribution, and water activity of extrudates were analyzed to determine the relationships among the raw material characteristics, extruder response parameters, and extrudate quality. At a WG ratio of 50%, the extrudates have the lowest hardness (2.76 kg), the highest springiness (0.95), and a fibrous degree of up to 1.75. The addition of WG caused a significant rightward shift in the relaxation time of hydrogen protons in the extrudates, representing increased water mobility and water activity. A ratio of 50:50 gave the smallest total color difference (ΔE) (about 18.12). When the added amount of WG was 50% or less, it improved the lightness and reduced the ΔE compared to >50% WG. Therefore, clarifying the relationship among raw material characteristics, extruder response parameters, and extruded product quality is helpful in the systematic understanding and regulation of the fiber textural process of binary protein meat analogs.

Developments of Plant-Based Emulsion-Type Sausage by Using Grey Oyster Mushrooms and Chickpeas

Plant-based (PB) meat alternatives are developing due to the consumer's demand, especially those who are mainly health-concerned. Soy proteins (SP) are commonly used as the main ingredients for PB meat analogues; however, SP may have adverse effects on the cognitive function and mood of humans. This study aimed to use grey oyster mushroom (GOM) and chickpea flour (CF) as an alternative source of SP to prepare emulsion-type sausages (ES). The effect of different hydrocolloids and oil on the quality of sausage was also investigated. The sausage was prepared using different concentrations of GOM and CF (20:20, 25:15, and 30:10 w/w). The GOM to CF ratio 25:15 was selected for the ES based on protein content, textural properties, and sensory attributes. The result indicated that sausage containing konjac powder (KP) and rice bran oil (RBO) provided a better texture and consumer acceptability. The final product showed higher protein (36%, dry basis), less cooking loss (4.08%), purge loss (3.45%), higher emulsion stability, and better consumer acceptability than the commercial sausage. The best recipe for mushroom-based ES is 25% GOM, 15% CF, 5% KP, and 5% RBO. In addition, GOM and CF could be an alternative option to replace SP in PB meat products.

Construction of 3D printed meat analogs from plant-based proteins: improving the printing performance of soy protein- and gluten-based pastes facilitated by rice protein

Additive technology (3D printing) is increasingly being used to produce plant-based meat analogs. However, there are several challenges to fabricating meat analogs using this technology: (i) the protein content in the final printed product is often too low to match the nutritional profile of real meat; (ii) it is often difficult to accurately mimic the textural and structural attributes of real meat using existing plant protein edible inks. In this study, the rheological properties and printing performance of edible inks produced from soy protein isolate (SPI), wheat gluten (WG), and rice protein (RP) were investigated. Our goal was to mix SPI, WG, RP powders to develop a high-protein edible ink (25% of total dry matter content) that can be used to create 3D-printed meat analogs. The rheological properties, moisture distribution, texture, microstructure, and printing performance (fidelity and stability) of protein pastes with different SPI-WG-to-RP ratios were measured. These protein-enriched inks exhibited pseudoplastic behavior with viscoelastic properties. The apparent viscosity and storage modulus of these pastes decreased with increasing rice protein proportion, which improved their 3D printing performance, such as hardness, support force, and plasticization. These edible inks prepared by mixed protein may be useful for 3D printing of plant-based foods.

Meat Analogues: Relating Structure to Texture and Sensory Perception

The transition from animal to plant proteins is booming, and the development of meat analogues or alternatives quickly progressing. However, the acceptance of meat analogues by consumers is still limited, mainly due to disappointing organoleptic properties of these foods. The objective of this study was to investigate possible relationships among structure, textural characteristics, consumer acceptance, and sensory evaluation of commercially available meat analogues. The microstructure and texture of 13 chicken analogue pieces and 14 analogue burgers were evaluated with confocal laser scanning microscopy (CLSM) and texture profile analysis (TPA). The moisture of the samples was related to cooking losses and release of liquid upon compression after cooking. Meat products were included as references. A sensory panel (n = 71) evaluated both flavour and texture characteristics. For the chicken analogue pieces, samples with more added fibres had a harder and chewier texture but were less cohesive. No other relations between composition and structure/texture could be found. In the sensory evaluation, lower hardness and chewiness were only seen in products with more fat. A lower sensory hardness was found to be related to the presence of small air pockets. For analogue burgers, there was no clear relation between composition and structure/texture. However, instrumentally measured hardness, chewiness, and cohesiveness correlated well with the corresponding sensory attributes, even though they could not be clearly linked to a structural feature. Next to this, fat content showed a clear correlation to perceived fattiness. CLSM images of burgers with high perceived fattiness showed large areas of fat. Therefore, the release of large fat pools from the meat was most likely responsible for the perception of this attribute. However, perceived fattiness was not related to liking, which was the case also for chicken analogue pieces. For both pieces and burgers, even if some of the measured textural attributes could be linked to the sensory profile, the textural attributes in question could not explain the liking scores. Liking was related to other aspects, such as meaty flavour and juiciness, which were not directly linked to compositional or textural features. Juiciness was not directly related to the moisture loss of the products, indicating that this attribute is rather complex and probably involves a combination of characteristics. These results show that to increase the appreciation of meat analogues by consumers, improving simple texture attributes is not sufficient. Controlling sensory attributes with complex cross-modal perception is probably more important.

Influence of wet extrudates from pumpkin seed proteins on drying, texture, and appearance of dry-cured hybrid sausages

Hybrid meat products represent a promising, more sustainable alternative to all-meat formulations. However, differences among plant- and animal-based proteins may alter traditional handling and final product properties. In this study, pork meat was partially replaced with texturized pumpkin seed proteins at 12.5, 25, 37.5, and 50% to obtain dry-cured hybrid meat sausages and their ripening (acidification, drying) during 21 days and final product properties (texture, sensory) were characterized and compared to a control (all-meat formulation). The drying behavior and distribution of moisture and free water of hybrids with extrudate contents of 12.5 and 25% were comparable to the sample made with meat and no significant (p > 0.05) differences in proximate composition were found. In contrast, higher meat replacement levels resulted in distinct changes of compositional and textural attributes i.e. chewiness was decreasing by up to 70%. Results suggested 25% of extrudates as an important threshold in manufacture of hybrid dry-cured sausages due to alterations in their ability to bind or release water. Results may be used to understand the influence of alternative texturized proteins in hybrid formulations and help product developers to understand related process and product relevant changes.

Removal of phenolic compounds from de-oiled sunflower kernels by aqueous ethanol washing

Selective removal of phenolic compounds (PCs) from de-oiled sunflower kernel is generally considered a key step for food applications, but this often leads to protein loss. PC removal yield and protein loss were assessed during an aqueous or aqueous ethanol washing process with different temperatures, pH-values and ethanol contents. PC yield and protein loss increased when the ethanol content was < 60% or when a higher temperature was applied. Our main finding is that preventing protein loss should be the key objective when selecting process conditions. This can be achieved using solvents with high ethanol content. Simulation of the multi-step exhaustive process showed that process optimization is possible with additional washing steps. PC yield of 95% can be achieved with only 1% protein loss using 9 steps and 80% ethanol content at 25℃. The functional properties of the resulting concentrates were hardly altered with the use of high ethanol solvents.