Effects of κ-Carrageenan and Guar Gum on the Rheological Properties and Microstructure of Phycocyanin Gel

Impact of Saturated and Unsaturated Oils on the Nonlinear Viscoelasticity, Microstructure, and 3D Printability of Fish Myofibrillar-Protein-Based Pastes and Gels

The effect of oil incorporation (soybean oil [SO] and coconut oil [CO] at 0, 1, 3, and 5 g/100 g) on the rheological, structural, and 3D printing properties of fish myofibrillar protein (MP, also known as surimi) paste and gel was investigated. Small-amplitude oscillatory shear (SAOS) tests showed that increasing oil concentration reduced the storage modulus (G'), weakening the gel network. Large-amplitude oscillatory shear (LAOS) analysis revealed strain-stiffening shifts and nonlinearity at γ = 5%. CO-containing gels exhibited higher hardness and gumminess, particularly at lower concentrations, due to enhanced protein-lipid interactions. In contrast, SO-containing gels showed reduced strength at higher concentrations, indicating phase separation. SEM confirmed that CO promoted a denser network, while SO led to a more porous structure, especially at 5% oil. Three-dimensional printing analysis demonstrated that both oils improved extrusion flowability by reducing nozzle friction. However, CO-containing samples maintained post-extrusion stability at 85% moisture, whereas SO-containing samples collapsed after multiple layers due to excessive softening. These findings highlight oil's dual role in MP gels, enhancing lubrication and flowability while compromising rigidity. The results offer valuable insights for developing soft, texture-controlled foods using 3D printing, especially for personalized nutrition applications such as elderly care or dysphagia-friendly diets.

Preparation of sodium alginate / quaternary ammonium-functionalized chitosan adsorbents: For the removal of high-molecular-weight invert sugar alkaline degradation products

The composite adsorbent consisting of sodium alginate (SA) and quaternary ammonium-functionalized chitosan (QACS) was prepared using the calcium slow-release method to remove high-molecular-weight invert sugar alkaline degradation products (HISADPs) from the beet juice. The SA/QACS composite adsorbent has a honeycomb porous structure. Comparing the single-component QACS dispersion and SA adsorbent, the incorporation of SA increased the storage/elastic modulus (G') and loss/viscous modulus (G'') of the SA/QACS composite hydrogels, while the incorporation of QACS enhanced the adsorption capacity of the SA/QACS composite adsorbents. Specifically, when 5 % QACS and 2 % SA were added, both G' and G" of the SA/QACS adsorbent were approximately 100 times greater than those corresponding to the QACS dispersion. Concurrently, its maximum adsorption capacity attained 164.5 mg/g, which was superior to that of the SA adsorbent. The adsorption isotherms and adsorption kinetics further demonstrated that the Langmuir model and the pseudo-second-order (PSO) model were congruent with the adsorption data of the SA/QACS composite adsorbent concerning HISADPs. Overall, these findings highlight the potential of the SA/QACS adsorbent as an effective adsorbent for the removal of HISADPs from beet juice.

Composite gel based on κ-carrageenan-soybean isolate protein/soy protein fibrils: Focus on structural differences and gel properties

The effects of different concentrations of κ-carrageenan (κC) on the structure and gel properties of soybean protein isolate (SPI) and soybean protein fibrils (SPF) were investigated in this work. The interaction between κC and SPI/SPF was explored by SDS-PAGE, FTIR, fluorescence spectroscopy, surface hydrophobicity (H0). Results indicated that the binding of κC to SPI and SPF is mainly hydrogen bonding and hydrophobic interactions. With the increase of κC concentration, the fluorescence intensity and H0 of SPI/SPF-κC decrease. When κC was 8 mg/mL, the H0 of SPI/SPF-κC decreased by 53.56 % and 57.23 % respectively. The addition of κC increased the particle size and turbidity of SPI, while the opposite results for SPF. The gel properties of SPI/SPF-κC were evaluated by texture, rheology and LF-NMR. The results showed that the gel properties of SPF were better than those of SPI, and the addition of κC significantly increased the G', apparent viscosity and resistance to denaturation of the gel. When κC concentration was 8 mg/mL, the hardness of SPI/SPF-κC was 127.2 ± 5.82 g and 134.23 ± 5.89 g, respectively. In conclusion, the fibrillation of proteins and κC can effectively improve the gel properties of SPI gels, which provides a theoretical basis for expanding the high-value utilization of SPI and SPF.

Gellan Gum Enhances the Quality of Egg-Based Yoghurt by Changing the Water Phase Distribution and Improving the Gel Texture

Egg-based yoghurt (EBY) is a novel yoghurt fermented by lactic acid bacteria with high nutritional and health values, serving as a potential alternative to milk-based yoghurt. However, the hardness, adhesiveness, and water-holding capacity of egg-based yoghurt need to be further improved. In this study, the improvement in EBY quality by gellan gum and its underlying mechanism were investigated. The results showed that gellan gum significantly improved the quality of EBY (p < 0.05). Among the five concentration gradients tested, the EBY supplemented with 0.045% gellan gum exhibited the best quality with the highest sensory score of 83.57. With the increasing amount of gellan gum, hydrogen bonding interactions in the yoghurt significantly increased, while ionic bonding remained unchanged, but hydrophobic interactions and disulphide bonding gradually decreased. Low-field NMR assay results demonstrated that gellan gum significantly raised the amount of strongly bonded water while decreasing the amount of immobile water in the yoghurt. Confocal laser scanning microscopy revealed that EBY with 0.045% gellan gum had a better texture, whereas too much or too little gellan gum led to a coarser structure. In summary, gellan gum altered the water phase state and enhanced the water holding capacity through increased hydrogen bonding interactions, which consequently improved the yoghurt's texture and sensory qualities. This study provides a reference for the development and application of EBY.

Ultrasonic treatment of emulsion gels with different soy protein-hemp protein composite ratios: Changes in structural and physicochemical properties

To improve the emulsion gel system of single soybean isolate protein (SPI) and to broaden the application field of hemp protein isolate (HPI), ultrasonic treatment and HPI were introduced to improve the properties of SPI emulsion gel and to explore the mechanism. The results showed that the gel strength (218.6 g) and water-holding capacity (86.24 %) of the emulsion gels were improved under ultrasonic treatments when the ratio of SPI:HPI was >6:4, and the reticulation structure of the gels was enhanced. When the ratio of SPI:HPI was <6:4, the gel structure was loose and formless. Ultrasonic treatment has a significant effect on the emulsion gel with the ratio of SPI:HPI was >6:4. Appropriate ultrasonic treatment (400 W) changed the protein structure, improved the rheological properties of emulsion gels to form the protein-oil-coated network structure. However, excessive ultrasonic treatment (600 W) will destroy the conformation of the protein, reducing the stability of the structure. The effect of ultrasonic treatment on emulsion gels with the ratio of SPI:HPI was <6:4 is low, but improved the gel protein digestibility. This study provides a theoretical basis for the application of ultrasonic in composite protein emulsion gels systems and the development and application of HPI.

Microencapsulation and nanoencapsulation of bacterial probiotics: new frontiers in Alzheimer's disease treatment

Alzheimer's disease, a progressive neurodegenerative disorder marked by cognitive decline, affects millions worldwide. The presence of amyloid plaques and neurofibrillary tangles in the brain is the key pathological feature, leading to neuronal dysfunction and cell death. Current treatment options include pharmacological approaches such as cholinesterase inhibitors, as well as non-pharmacological strategies like cognitive training and lifestyle modifications. Recently, the potential role of probiotics, particularly strains, such as Lactobacillus and Bifidobacterium, in managing neurodegenerative diseases through the gut-brain axis has garnered significant attention. Probiotics can modulate inflammation, produce neurotransmitters, and support neuronal health, potentially slowing disease progression and alleviating symptoms, such as stress and anxiety. Optimizing the pharmacotherapeutic effects of probiotics is critical and involves advanced formulation techniques, such as microencapsulation and nanoencapsulation. Microencapsulation employs natural or synthetic polymers to protect probiotic cells, enhancing their viability and stability against environmental stressors. Methods like extrusion, emulsion, and spray-drying are used to create microcapsules suited for various applications. Nanoencapsulation, on the other hand, operates at the nanoscale, utilizing polymeric or lipid-based nanoparticles to improve the bioavailability and shelf life of probiotics. Techniques, such as nanoprecipitation and emulsification, are employed to ensure stable nanocapsule formation, thereby augmenting the therapeutic potential of probiotics as nutraceutical agents. This study delves into the essential formulation aspects of microencapsulation and nanoencapsulation for beneficial probiotic strains, aimed at managing Alzheimer's disease by optimizing the gut-brain axis. The insights gained from these advanced techniques promise to enhance probiotic delivery efficacy, potentially leading to improved health outcomes for patients suffering from neurodegenerative disorders.

Effect of the Ratio of Protein to Water on the Weak Gel Nonlinear Viscoelastic Behavior of Fish Myofibrillar Protein Paste from Alaska Pollock

The linear and nonlinear rheological behaviors of fish myofibrillar protein (FMP) paste with 75%, 82%, and 90% moisture content were evaluated using small-amplitude oscillatory shear (SAOS) and large-amplitude oscillatory shear (LAOS) tests. SAOS revealed pastes with 75% and 82% moisture exhibited solid-like behavior, characterized by higher storage modulus (G') than loss modulus (G″), indicative of weak gel properties with a strong protein interaction. In contrast, the 90% moisture content showed more viscous behavior due to weakened protein-protein entanglements. The frequency exponent (n' and n″) from the power law equation varied slightly (0.24 to 0.36), indicating limited sensitivity to changes in deformation rate during SAOS. LAOS tests revealed significant structural changes, with Lissajous-Bowditch curves revealing early nonlinearities at 10% strain for 90% moisture content. Decomposed Chebyshev coefficients (e3/e1, v3/v1, S, and T) indicated strain stiffening at lower strains for the 75% and 82% moisture pastes (i.e., < 50% strain for 75% and < 10% strain for 82%), transitioning to strain thinning at higher strains. Additionally, numerical model confirmed the predictability of the 3D printing process from the nonlinear rheological data, confirmed the suitability of the 75% and 82% moisture pastes for applications requiring structural integrity. These insights are essential for optimizing processing conditions in industrial applications. The findings suggest that the 75% and 82% moisture pastes are suitable for applications requiring structural integrity, while the 90% moisture paste is ideal for flow-based processes. These insights are essential for optimizing processing conditions in industrial applications.

Investigating the Synergistic Effects of Carvacrol and Citral-Edible Polysaccharide-Based Nanoemulgels on Shelf Life Extension of Chalkidiki Green Table Olives

Modern bioeconomy and sustainability demands lead food technology in the development of novel biobased edible food preservatives. Herein, the development and characterization of novel polysaccharide (xanthan gum and kappa-carrageenan)-based nanoemulgels (NGs) enhanced with essential oil derivatives; pure citral (CT); pure carvacrol (CV); and various CT:CV ratios (25:75, 50:50, and 75:25) are presented. The obtained NGs are applied as active edible coatings for extending the shelf life of Protected Designation of Origin (PDO) green table olives of Chalkidiki. The zeta potential demonstrated the high stability of the treatments, while light scattering measurement and scanning electron microscopy images confirmed the <100 nm droplet size. EC50 indicated high antioxidant activity for all the tested samples. The fractional inhibitory concentration (FIC) confirmed the synergistic effect of NG with a CT:CV ratio at 50:50 against Staphylococcus aureus and at CT:CV ratios 25:75 and 75:25 against E. coli O157:H7. NG coatings with CT:CV ratios at 50:50 and at 25:75 effectively controlled the weight loss at 0.5%, maintained stable pH levels, and preserved the visual quality of green olives on day 21. The synergistic effect between CT and CV was confirmed as they reduced the spoilage microorganisms of yeasts and molds by 2-log [CFU/g] compared to the control and almost 1 log [CFU/g] difference from pure CT and CV-based NGs without affecting the growth of beneficial lactic acid bacteria crucial for fermentation. NGs with CT:CV ratios at 50:50 and at 25:75 demonstrated superior effectiveness in preventing discoloration and maintaining the main sensory attributes. Overall, shelf life extension was achieved in 21 compared to only 7 of the uncoated ones. Finally, this study demonstrates the potential of polysaccharide-based NGs in mixtures of CT and CV for the shelf life extension of fermented food products.

Incorporation of amylose improves rheological and textural properties of Moringa oleifera seed salt-soluble protein

The interactions between corn amylose (CA) and Moringa oleifera seed salt-soluble protein (MOSP) were explored to improve the gel properties of MOSP. With increasing CA content, the MOSP-CA gel network structure was improved but the size of the gel porosity decreased firstly and then increased; the water holding retention (WHR) of MOSP-CA was decreased from approximately 94 % to 85.43 ± 2.54 %. The MOSP-CA-2.5 gel exhibited the best water holding stability (WHS), with a value of 37.1 ± 0.33 %. The MOSP-CA gel hardness increased with CA concentration, and MOSP-CA-2.5 showed relatively optimal cohesiveness, elasticity, adhesiveness, and chewiness. Meanwhile, MOSP-CA-2.5 exhibited gel strength. Incorporation of CA significantly increased the exposure of hydrophobic residues and the concentration-dependent increase in disulfide bonds in MOSP-CA gel. Thus, hydrophobic interactions, hydrogen bonds, and disulfide bonds collectively stabilized the structure of MOSP-CA gel. The findings would broaden the application of MOSP and improve the utilization value of MOSP in various industries.

A review of phycocyanin: Production, extraction, stability and food applications

This paper aims to review the production, extraction, stability and food application of phycocyanin. Currently, light source modulation and organic solvent cultivation of high biomass phycocyanin is an important research direction. The development of nitrogen oxygen balanced system-assisted culture environments to raise production will become a trend, the green and sustainable characteristics of which compensate for the drawbacks of the former. Microfiltration, ultrafiltration, and ultrasonic cell rupture technologies address the drawbacks of solvent extraction and achieve a significant increase in purity. Biorefining technology may become the trend to achieve the highest purity and efficiency in large-scale production of phycocyanin. For the stability of phycocyanin, the development of complexes is a trend, but it should consider the suitability of the materials complex with them for production as foodstuffs. Phycocyanin is mainly developed as a natural pigment, and the main point is the coloring power and stability of natural pigments.

Comparison of Soy and Pea Protein for Cultured Meat Scaffolds: Evaluating Gelation, Physical Properties, and Cell Adhesion

Cultured meat is under investigation as an environmentally sustainable substitute for conventional animal-derived meat. Employing a scaffolding technique is one approach to developing cultured meat products. The objective of this research was to compare soy and pea protein in the production of hydrogel scaffolds intended for cultured meat. We examined the gelation process, physical characteristics, and the ability of scaffolds to facilitate cell adhesion using mesenchymal stem cells derived from porcine adipose tissue (ADSCs). The combination of soy and pea proteins with agarose and agar powders was found to generate solid hydrogels with a porous structure. Soy protein-based scaffolds exhibited a higher water absorption rate, whereas scaffolds containing agarose had a higher compressive strength. Based on Fourier transform infrared spectroscopy analysis, the number of hydrophobic interactions increased between proteins and polysaccharides in the scaffolds containing pea proteins. All scaffolds were nontoxic toward ADSCs, and soy protein-based scaffolds displayed higher cell adhesion and proliferation properties. Overall, the soy protein-agarose scaffold was found to be optimal for cultured meat production.

Highly swellable, cytocompatible and biodegradeable guar gum-based hydrogel system for controlled release of bioactive components of liquorice (Glycyrrhiza glabra L.): Synthesis and evaluation

Glycyrrhiza glabra Linn (liquorice) has been widely used for therapeutic purposes to treat digestive disorders, immunomodulatory disorders, inflammatory disorders, diabetes, viral infections, and cancer. Liquorice contains a wide variety of bioactive compounds, including glycyrrhizin, flavonoids, and terpenoids. Several factors compromise their therapeutic efficacy, such as poor pharmacokinetic profiles and physicochemical properties. Therefore, to improve its overall effectiveness, liquorice solid dispersion (LSD) was incorporated into biopolymer-based guar gum-grafted-2-acrylamido-2-methylpropane sulfonic acid (Guar gum-g-AMPS) hydrogels designed for controlled delivery via the oral route and characterized. The qualitative analysis of LSD revealed 51 compounds. Hydrogel structural properties were assessed for their effect on swelling and release. The highest swelling ratio (6413 %) and drug release (84.12 %) occurred at pH 1.2 compared to pH 7.4 (swelling ratio of 2721 % and drug release of 79.36 %) in 48 h. The hydrogels exhibited high porosity (84.23 %) and biodegradation (9.30 % in 7 days). In vitro hemolysis tests have demonstrated the compatibility of the hydrogel with blood. CCK-8 assay confirmed the biocompatibility of the synthesized hydrogel using osteoblasts and RIN-m5f cells. LSD exhibited good anti-inflammatory activity when loaded into hydrogels after being subjected to protein denaturation experiments. Moreover, LSD-loaded hydrogels have good antioxidant and antibacterial properties.

Narrative Review of the Current and Future Perspectives of Phycobiliproteins' Applications in the Food Industry: From Natural Colors to Alternative Proteins

Vivid-colored phycobiliproteins (PBPs) have emerging potential as food colors and alternative proteins in the food industry. However, enhancing their application potential requires increasing stability, cost-effective purification processes, and consumer acceptance. This narrative review aimed to highlight information regarding the critical aspects of PBP research that is needed to improve their food industry potential, such as stability, food fortification, development of new PBP-based food products, and cost-effective production. The main results of the literature review show that polysaccharide and protein-based encapsulations significantly improve PBPs' stability. Additionally, while many studies have investigated the ability of PBPs to enhance the techno-functional properties, like viscosity, emulsifying and stabilizing activity, texture, rheology, etc., of widely used food products, highly concentrated PBP food products are still rare. Therefore, much effort should be invested in improving the stability, yield, and sensory characteristics of the PBP-fortified food due to the resulting unpleasant sensory characteristics. Considering that most studies focus on the C-phycocyanin from Spirulina, future studies should concentrate on less explored PBPs from red macroalgae due to their much higher production potential, a critical factor for positioning PBPs as alternative proteins.

Formulation and Characterization of Sustainable Algal-Derived Nanoemulgels: A Green Approach to Minimize the Dependency on Synthetic Surfactants

Phycocyanin (PC), a natural protein that is very interesting from the medical point of view due to its potent antioxidant and anti-inflammatory properties, is obtained from algae. This compound is gaining positions for applications in the food industry. The main objective of this work was to obtain nanoemulgels formulated with PC and k-carrageenan (a polymer that is obtained from algae as well). An optimization of the processing parameters (homogenization pressure and number of cycles) and the ratio of PC and a well-known synthetic surfactant (Tween 80) was developed using response surface methodology. The results of this optimization were 25,000 psi, seven cycles, and a 1:1 ratio of PC/Tween80. However, the necessity for the incorporation of a polymer that plays a thickener role was observed. Hence, k-carrageenan (k-C) was used to retard the creaming process that these nanoemulsions suffered. The incorporation of this biopolymer provoked the creation of a network that showed gel-type behavior and flow indexes very close to zero. Thanks to the combined use of these two sustainable and algae-obtained compounds, stable nanoemulgels were obtained. This work has proved that the combined use of PC and k-C has emerged as a sustainable alternative to stabilize dispersed systems for the food industry.

Carboxymethyl chitosan/polyvinyl alcohol double network hydrogels prepared by freeze-thawing and calcium chloride cross-linking for efficient dye adsorption

The discharge of dye wastewater resulting from rapid industrial development has become a serious environmental concern. Therefore, there is a pressing need to develop efficient methods and technologies for the removal of dye pollutants. This study introduced a double network hydrogel, with varying carboxymethyl chitosan (CMCS) contents and polyvinyl alcohol (PVA), employing a combination of freeze- thawing and calcium chloride cross-linking. The investigation focused on the rheological properties of the hydrogels and their removal ability of acidic blue 93 (AB). The results showed that the strength and viscoelastic modulus of composite hydrogels were positively correlated with the CMCS content, and all composite hydrogels exhibited the typical weak strain overshoot behavior. The pore size of the gel initially decreased and then increased, with the densest pores observed at 4 wt% CMCS, showing the optimal removal ability for AB. The adsorption process followed pseudo second-order kinetic model, dominated by external diffusion, and exhibited inhomogeneous multilayer adsorption. This study unveils the potential of CMCS/PVA gels as adsorbents, offering inspirations for the design and development of polyvinyl alcohol-based gels for applications in the food industry.

Effects of hydrocolloids as fat-replacers on the physicochemical and structural properties of salt-soluble protein isolated from water-boiled pork meatballs

Konjac glucomannan (KGM), xanthan gum (XG), guar gum (GG), and κ-carrageenan (KC), as substituent, are commonly used in ground pork products. Here, the content of these (0.5, 1.0, 1.5, and 2.0%, w/w) on the gel properties, thermal properties, and interaction forces of salt-soluble protein (SSP) isolated from water-boiled pork meatballs were investigated. We found 1.0% KGM, 0.5% XG, 0.5-2.0% GG, and 0.5-2.0% KC to water-boiled pork meatballs exerted a positive effect on the denaturation temperature, hydrogen bonds, hydrophobic interactions, disulfide bonds, α-helix, and β-sheet content of SSP, as well as the strength and storage modulus of the modified protein gel. The addition of these hydrocolloids with the addition of 1.0% aggregated myosin and actin, led to the enhancement of the bands corresponding to myosin heavy chain and actin. The prediction model of gel strength showed that the gel strength was negatively correlated with Tpeak1, Tpeak2, and ionic bond. This study provides theoretical guidance for improving the application of hydrocolloids in pork-based foods.

Drug delivery based on a supramolecular chemistry approach by using chitosan hydrogels

Microbial infections are a serious healthcare related problem, causing several complications and even death. That is why, the development of new drug delivery systems with prolonged effect represents an interesting research topic. This study presents the synthesis and characterization of new hydrogels based on chitosan and three halogenated monoaldehydes. Further, the hydrogels were used as excipients for the development of drug delivery systems (DDS) by the incorporation of fluconazole, an antifungal drug. The systems were structurally characterized by Fourier Transformed Infrared Spectroscopy and Nuclear Magnetic Resonance, both methods revealing the formation of the imine linkages between chitosan and the aldehydes. The samples presented a high degree of ordering at supramolecular level, as demonstrated by WXRD and POM and a good water-uptake, reaching a maximum of 1.6 g/g. The obtained systems were biodegradable, loosing between 38 and 49 % from their initial mass in the presence of lysozyme in 21 days. The ability to release the antifungal drug in a sustained manner for seven days, along with the high values of the inhibition zone diameter, reaching a maximum of 64 mm against Candida parapsilosis for the chlorine containing sample, recommend these systems as promising materials for bioapplications.

Controlled Release of Phycocyanin in Simulated Gastrointestinal Conditions Using Alginate-Agavins-Polysaccharide Beads

C-phycocyanin (CPC) is an antioxidant protein that, when purified, is photosensitive and can be affected by environmental and gastrointestinal conditions. This can impact its biological activity, requiring an increase in the effective amount to achieve a therapeutic effect. Therefore, the aim of this study was to develop a microencapsulate of a complex matrix, as a strategy to protect and establish a matrix for the controlled release of CPC based on polysaccharides such as agavins (AGV) using ionic gelation. Four matrices were formulated: M1 (alginate: ALG), M2 (ALG and AGV), M3 (ALG, AGV, and κ-carrageenan: CGN), and M4 (ALG, AGV, CGN, and carboxymethylcellulose: CMC) with increasing concentrations of CPC. The retention and diffusion capacities of C-phycocyanin provided by each matrix were evaluated, as well as their stability under simulated gastrointestinal conditions. The results showed that the encapsulation efficiency of the matrix-type encapsulates with complex composites increased as more components were added to the mixtures. CMC increased the retention due to the hydrophobicity that it provides by being in the polysaccharide matrix; CGN enabled the controlled diffusive release; and AGV provided protection of the CPC beads under simulated gastrointestinal conditions. Therefore, matrix M4 exhibited an encapsulation efficiency for CPC of 98% and a bioaccessibility of 10.65 ± 0.65% after the passage of encapsulates through in vitro digestion.

Conformational changes and physicochemical attributes of texturized pea protein isolate-konjac gum: With a new perspective of residence time during extrusion

The present study aimed to investigate the effects of different extrusion temperatures (110, 130 and 150 °C) and konjac gum addition (0.1 %, 0.2 %, and 0.3 %) on the flow behavior, physicochemical properties and microstructure of extruded pea protein isolate (PPI). The results showed that the textured protein could be improved by enhancing the extrusion temperature and adding konjac gum during extrusion. The water/oil holding capacity of PPI decreased and the SH content increased after extrusion. With temperature and konjac gum content increased, the β-sheet of extruded proteins transformed to other secondary structural components, and Trp residue transformed to a more polar environment, illustrating the changes in protein conformation. All extruded samples presented as yellow hue with little green and higher lightness, while excessive extrusion process reduced the brightness and promoted more formation of browning pigments. Extruded protein showed more associated layered with some air pores, and its hardness and chewiness increased with the increase of temperature and konjac gum concentration. Cluster analysis showed that the addition of konjac gum could effectively improve the quality characteristics of pea protein under low temperature extrusion, and the effect was similar to that of high temperature extrusion product. With the increase of konjac gum concentration, the flow pattern of protein extrusion gradually converted from plug flow to mixing flow, and the disorder degree of polysaccharide protein mixing system was enhanced. Moreover, Yeh-jaw model showed better fitting effect in F(θ) curves compared to Wolf-white.