Effects of native starch and modified starches on the textural, rheological and microstructural characteristics of soybean protein gel

Effects of transglutaminase on the gelation properties and digestibility of pea protein isolate with resonance acoustic mixing pretreatment

Our previous research confirmed that resonance acoustic mixing (RAM) pretreatment effectively improved the emulsification and water retention of commercial pea protein isolate (PPI), but significantly reduced its gel performance. This study aimed to investigate the effect of transglutaminase (TGase, 0.1 %, 0.2 %, 0.3 %, 0.4 %, and 0.5 %) on the gel properties and digestibility of PPI with RAM pretreatment (RAM-PPI). Results showed that moderate TGase (0.1-0.3 %) significantly increased the α-helix/β-sheet ratio, surface hydrophobicity and covalent crosslinking of protein molecules, enhancing the texture and digestibility of RAM-PPI gels. The SEM imaging demonstrated a fine, uniform and dense network structure with many pores in these RAM-PPI gels. However, excessive TGase (0.5 %) reduced the water holding capacity and intestinal digestibility of the RAM-PPI gels, mainly due to the excessive protein cross-linking and re-aggregation. These findings suggest that the combined treatment of moderate TGase with RAM can be a promising approach for the modification of plant-based proteins.

Effects of pH shift and D-galactose on network structure of glycinin gel and diffusion behavior of non-network proteins

To reduce the content of non-network proteins in protein-based gels, a synergistic approach involving pH shift and D-galactose (DG) was developed herein to obtain elastic gels with dense networks. The results revealed that the combined effect of pH shift and DG promoted the formation of additional disulfide bonds and chemical bonds between molecules, resulting in a denser, and highly elastic gel network, which immobilized more aggregates, leading to a significant reduction in non-network protein content, and enhancing the functional properties of the gel. Moreover, non-network proteins primarily consisted of subunit A4 (mostly Glu and Asp), while the subunit B was the primary polypeptide forming the gel network. Therefore, the removal of the non-network protein has no significant effect on the microstructure, water holding capacity, elasticity, and recovery of the gel. Comprehensively, the combination of pH shift and DG generated a positive synergistic effect of the glycinin hydrogel network structure.

Effects of different binding strategies of D-galactose and glycinin on the thermal gelation behavior of the composite system

In this study, non-covalent and covalent interactions between D-galactose (DG) and glycinin (11S) were induced using a pH-shift method. This approach represents an innovative advancement in existing protein-monosaccharide binding strategies. Furthermore, the study investigated the resulting changes in gel behavior and the properties of the composite thermal gels. The solubility and Zeta-potential analysis showed that the non-covalent interaction (S-11S/DG) was more stable and less dispersed than the covalent interaction (S/DG-11S). Rheological results showed that S-11S/DG has higher viscosity and can form stable elastic gel after temperature program. FTIR and intermolecular force results indicated that both gels utilized disulfide bonds as the primary covalent force, with additional chemical bonds playing a secondary role in maintaining the stability of the gel network and surrounding water molecules. However, the S/DG-11S exhibits a looser structure, resulting in a less elastic and thinner network structure. In contrast, the S-11S/DG gel network demonstrated increased elasticity and support, enhancing its hardness, cohesion and water holding capacity. Thus, the pH-shifting-induced non-covalent gel system had more stable network structure and better properties than the pH-shifting-induced covalent gel system. This study offered new insights for constructing soybean protein gel systems and advancing the design of novel soybean protein products.

Effect of triple helix polysaccharides from foxtail millet bran on millet starch gel formation

Polysaccharides as modifiers can solve native starch gel problem of weaker gel strength and lower gelation trend. The key structures of foxtail millet bran polysaccharides (FMBPs) in improving millet starch gel properties were investigated. Results showed that FMBPs were high molecular weight (Mw) heteropolysaccharides and the distribution of total sugar, uronic acid and monosaccharides was non-uniform in four FMBPs. Structural analysis revealed triple helix polysaccharides (THPs) existed in independent triple helix (ITH) and aggregates forms. The redshift degree of Congo red-FMBP complexes illustrated that FMBP-S1 contain the most ITHs, followed by FMBP-S2 and FMBP-S4, and the least in FMBP-S3. The porous structure of FMBPs promoted the adsorption of Congo red, bringing about the increase in weight and volume of the complexes and eventual precipitation. Separation of THPs provided a new method to investigate its role in starch gel. The results showed FMBPs with more ITHs showed higher peak viscosity, breakdown and setback. The presence of ITHs could reduce gel point temperature (ΔT = 6.62-29.86 °C) and water holding capacity (from 50 to 66 ms to 231 ms), but improve the viscoelasticity of gel. The study not only improved the quality of starch-based gel but also achieved high-value utilization of foxtail millet bran.

Development and characterization of soy protein-based custard-like soft foods for elderly individuals with swallowing difficulties

There is growing interest in developing protein-rich foods for the elderly using plant proteins. The application of soy protein isolate (SPI) as a model protein to create protein-rich, custard-like soft foods presents a unique opportunity for innovative formulations tailored to those within the aging population suffering from swallowing difficulties. This study investigated the physicochemical and textural properties of custard-type soft food formulations developed using SPI for dysphagic elderly individuals, with the goal of achieving characteristics similar to those of optimal milk protein-based counterparts. The protein content in the SPI-based custards varied from 8.9 % to 13.9 % and the milk-protein based custards had 8.9 % protein content. There was a substantial difference in textural, rheological and creep resistance and other properties between SPI and milk protein-based formulations. The SPI-based custards also had lower water-holding capacity, looser structure, and higher level of insoluble protein aggregates. The SPI-based custards imparted a more spreadable mouthfeel suitable for the aging population. The custards containing 13.9 % SPI had higher gel strength, viscosity, texture, and product stability. All of these custards were classified as Level 6 - Soft & Bite-sized dysphagia diet, based on International Dysphagia Diet Standardisation Initiative (IDDSI) tests. Instrumental IDDSI tests for Level 6 foods corroborated these observations, yielding reliable and consistent data. This research provides insights for developing protein-rich plant-based soft foods intended for the elderly population that have characteristics close to milk protein-based custards and comply with IDSSI criteria.

Effect of ultrasonic pretreatment on physicochemical, thermal, and rheological properties of chemically modified corn starch

This study investigated the effects of ultrasonic and three chemical individual and dual modification treatments on corn starch's physicochemical, thermal, and rheological properties. Ultrasonication and the three chemical treatments disrupted the starch granules with a decrease in particle size and a significant increase in the ζ-potential. The hydrophilicity of ultrasonic-oxidized dual-modified starch (U-O-CS) was the highest, at 0.854 g/g. The lipophilicity of ultrasonic-esterified dual-modified starch (U-E-CS) was the highest, at 1.485 g/g. The gelatinization temperature of ultrasonic, oxidation, and cross-linking modified starches increased significantly, with cross-linking starches being the largest. Oxidative treatment significantly decreased the starch's G' and G" and weakened the textural properties. The rheological properties of U-O-CS were further weakened. The G' of the starch decreased after the esterification treatment, while the G" increased, and the textural properties were cut. The maximum rheological and textural properties were obtained for crosslinked modification, with a hardness value of 284.70 g.

The Viscoelastic Behavior of Legume Protein Emulsion Gels-The Effect of Heating Temperature and Oil Content on Viscoelasticity, the Degree of Networking, and the Microstructure

Legume proteins are increasingly used in structuring various foods under the influence of heating and stirring energy. Based on available studies, this structuring potential is not yet fully understood. This raises the question of the suitability of legume isolates and concentrates for structuring in emulsion gels and the effect of heat and oil on the gel properties. In this study, soy- and pea-based suspensions and emulsions were prepared with the least gelling concentration using different oil concentrations (0%, 7.5%, 15%, 22.5%, and 30%). The viscoelastic properties were measured before and after heating cycles (65 °C and 95 °C). Scanning electron microscopy images complemented the results. All gels measured showed viscoelastic solid behavior. Thermal treatment showed a positive effect on the gel properties for most samples, especially for concentrates (reduction in the loss factor and networking factor > 1). The concentrates showed much higher networking factors and tighter cross-linking than the isolates. The rheological and microstructural properties of the emulsion gels are influenced by a number of factors, such as carbohydrate content, protein chemistry, the protein purification method, and initial viscosity. Moreover, the influence of oil on the rheological properties depends on the material used and whether oil droplets act as an active or inactive filler.

The properties of potato starch with different moisture content treated by cold plasma:Structure, physicochemical and digestive properties

To investigate the effect and mechanism of water on the structure, physicochemical properties, and in vitro digestibility of starch treated with CP, different moisture content (16.7 %, 28.6 %, 37.5 %, 44.4 %, and 50 %, w/w) were used, followed by treatment with CP (40 V, 1 A, 3 mins). Results show that CP treatment preserves the Maltese cross pattern, crystal morphology, and Fourier transform infrared spectroscopy spectra of potato starch. However, significant changes were observed in molecular weight, chain length distribution, average particle size, ordered structure, and relative crystallinity. As moisture content increased, the etching effect on the particle surface intensified, leading to further reductions in molecular weight and ordered structure. Concurrently, amylose content, solubility, relative crystallinity, and resistant starch content increased. At higher water levels, water molecules exhibited protective effects, mitigating CP-induced structural damage by reducing etching and loss of molecular weight. These findings suggest that the role of water in CP treatment is complex and provide insights into the interaction between CP and water in starch properties, highlighting its potential applications in starch-based foods.

Optimization of cold-induced aerated gels formed by Maillard-driven conjugates of SPI-gellan gum as an oil substitute in mayonnaise sauce

This research aimed at characterization of composite cold-set aerated gels composed of SPI-gellan gum Maillard conjugates. The optimized gel was eventually incorporated in mayonnaise sauce as an oil substitute. The optimum conditions were statistically determined as 1.5% SPI, 300 mM CaCl2, and 90 min heating time. All of which resulted 35% glycation degree and high molecular weight conjugates on top of SDS-PAGE injection wells. Increasing CaCl2 concentration enhanced the adsorption of conjugates at air-water interface, decreasing the density but increasing the WHC and hardness. Increasing heating time facilitated gelation which improved gel hardness. The optimized gel was microstructurally homogeneous with increased overrun (20.8%) and H-bonds. The rheological measurements showed viscoelastic gel network which was thermally stable up to 90 °C, besides increasing G', G" and η∗ at 85 °C. Substitution of optimized gel in mayonnaise sauce improved the nutritional value and thermal stability (77.13%), but declined calorie. The substituted mayonnaise sauce was greatly accepted by panelists. Thus, the aerated gel formed at optimum conditions had great structural and mechanical characteristics and its usage as an oil analogue induced a low-calorie mayonnaise sauce with acceptable sensory properties.

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.

Effects of acetylated distarch phosphate on the physicochemical characteristics and stability of the oyster sauce system

In this study, the effect of different acetylated distarch phosphate (ADSP) ratios (0, 1%, 2%, 3%, 4%, 5%) on the physicochemical characteristics and stability of the oyster sauce (OS) system was investigated. The texture, water state, interactions, rheological properties, microstructure, and stability of OS samples were analyzed through the texture analyser, low-field nuclear magnetic resonance (LF-NMR), particle diameter and zeta potential, fourier-transform infrared spectroscopy (FTIR), rheometer, and microscopes. The results revealed that the addition of ADSP improved the firmness, consistency, cohesiveness, and water-holding capacity of OS. Moreover, ADSP reduced the average particle size and zeta potential of OS, indicating that electrostatic and steric stabilization existed in the ADSP-OS system. The addition of ADSP enhanced the hydrogen bonding and decreased water mobility for OS system, processing a more continuous and smooth structure. All ADSP-OS samples were typical non-Newtonian fluids with shear-thinning characteristics. In addition, the non-significant instability index changes of ADSP-OS over the whole storage period confirmed the excellent long-term stabilization capability of OS prepared with ADSP. This study provides a theoretical basis for starch-based sauce products and contributes to the development of sauce products.

Soybean protein isolate-sodium alginate double network emulsion gels: Mechanism of formation and improved freeze-thaw stability

Soybean protein isolate (SPI) is widely used in the food industry. However, SPI-based emulsion gels tend to aggregate and undergo oiling-off during freeze-thawing. In this study, emulsion gels were prepared by a combination of heat treatment and ionic cross-linking using SPI and sodium alginate (SA) as raw materials. The focus was on exploring the mechanistic effects of the SPI-SA double network structure on the freeze-thaw stability of emulsion gels. The results showed that the addition of SA could form different types of network structures with SPI, due to different degrees of phase separation. In addition, SA appearing on the SPI network indicated that the addition of Ca2+ shielded the electrostatic repulsion between SPI and SA to form SPI-SA complexes. The disappearance of the characteristic peaks of SA and SPI in Fourier transform infrared spectroscopy analysis also confirmed this view. Low-field nuclear magnetic resonance data revealed that SA played a role in restricting water migration within the emulsion gels, increasing bound water content, and thereby improving the water-holding capacity of the emulsion gels. Therefore, the incorporation of SA improved the freeze-thaw stability of SPI emulsion gels. These findings offer a theoretical basis and technical support for SPI application in frozen products.

Interactions between rice starch and flavor components and their impact on flavor

Flavor is considered one of the most significant factors affecting food quality. However, it is often susceptible to environmental factors, so encapsulation is highly necessary to facilitate proper handling and processing. In this study, the structural changes in starch encapsulation and their effects on flavor retention were investigated using indica starch (RS) as a matrix to encapsulate three flavoring compounds, namely nonanoic acid, 1-octanol, and 2-pentylfuran. The rheological and textural results suggested that the inclusion of flavor compounds improved the intermolecular interactions between starch molecules, resulting in a significant increase in the physicochemical properties of starch gels in the order: nonanoic acid > 1-octanol > 2-pentylfuran. The XRD results confirmed the successful preparation of v-starch. Additionally, the inclusion complexes (ICs) were characterized using FT-IR, SEM, and DSC techniques. The results showed that v-starch formed complexes with Flavor molecules. The higher enthalpy of the complexes suggested that the addition of alcohols and acids could improve the intermolecular complexation between starch molecules. The retention rates of three flavor compounds in starch were determined using HS-GC, with the values of 51.7 %, 32.37 %, and 35.62 %. Overall, this study provides insights into novel approaches to enhance the quality and flavor retention, improve the storability and stability, reduce losses during processing and storage, and extend the shelf life of starchy products.

Evaluation of the functional properties of a protein isolate from Arthrospira maxima and its application in a meat sausage

Arthrospira maxima is a microalga that has been collected in Lake Texcoco in the Valley of Mexico since pre-Hispanic times and has been a traditional food source due to its high biomass production and protein content (50-60 %), making it promising for protein extraction. In this context, a protein isolate was obtained from powdered biomass of Arthrospira maxima (PbAm) by alkaline solubilization (pH 11) and isoelectric precipitation (pH 4.2). Arthrospira maxima protein isolate (AmPI) presented higher protein content (82.58 %) and total amino acids compared to PbAm. Functional properties of AmPI were evaluated in comparison with PbAm and soy protein isolate (SPI). Protein extraction resulted in a significant increase in protein solubility (PS) and foaming capacity (FC) of up to 87.78 % and 238.10 %, respectively. Emulsifying capacity (EC) of AmPI was superior to that of PbAm and SPI in pH range 5-7. Inclusion of AmPI as a partial substitute for SPI in the formulation of meat sausages was evaluated by implementing four treatments: T1 (15 % AmPI, 85 % SPI), T2 (10 % AmPI, 90 % SPI), T3 (5 % AmPI, 95 % SPI) and T4 (0 % AmPI, 100 % SPI). Although the texture attributes remained unchanged, a significant reduction in color parameters was observed as the concentration of AmPI increased. An inclusion of 15 % AmPI significantly enhanced the nutritional quality of meat sausages. Results highlight the excellent properties of AmPI, confirming Arthrospira maxima as a promising protein source in the food industry.

Effect of dielectric barrier discharge (DBD) plasma treatment on physicochemical and 3D printing properties of wheat starch

In recent years, the focus has shifted towards carbohydrate-based hydrogels and their eco-friendly preparation methods. This study involved an investigation into the treatment of wheat starch using dielectric barrier discharge (DBD) plasma technology over varying time gradients (0, 2, 5, 10, 15, and 20 min). The objective was to systematically examine the impact of different treatment durations on the physicochemical properties of wheat starch and the suitability of its gels for 3D printing. Morphology of wheat starch remained intact after DBD treatment. However, it led to a reduction in the amylose content, molecular weight, and crystallinity. This subsequently resulted in a decrease in the pasting temperature and viscosity. Moreover, the gels of the DBD-treated starch exhibited superior 3D printing performance. After a 2-min DBD treatment, the 3D printed samples of the wheat starch gel showed no significant improvements, as broken bars were evident on the surface of the 3D printed graphic, whereas DBD-20 showed better printing accuracy and surface structure, compared to the original starch without slumping. These results suggested that DBD technology holds potential for developing new starch-based gels with impressive 3D printing properties.

A composite gel formed by konjac glucomannan together with Nano-CF obtained by FeCl3-citric acid hydrolysis as a potential fat substitute

This study aims to fabricate composite gels using nano citrus fiber (Nano-CF) derived from the hydrolysis process of citric acid (CA) with FeCl3, with a simultaneous exploration of its potential as an substitute to fats. Investigation of varying FeCl3 concentrations (0.01 to 0.03 mmol/g of CA) revealed a significant enhancement in the water-holding and oil-retention capacity of the Nano-CF. The meticulous synthesis of the composite gels involved integrating nano citrus fibers with konjac glucomannan (KGM) through high-speed shearing, followed by a comprehensive evaluation of its microstructure and physicochemical attributes. Increasing the Nano-CF concentration within the gels led to a synergistic interaction with KGM, resulting in enhanced viscosity, improved thermal stability, and restricted water molecule mobility within the system. The gels initially displayed reduced firmness, resilience, and adhesive characteristics, followed by subsequent improvement. When the ratio of Nano-CF to KGM was 0.5:1, the composite gels exhibited texture parameters, viscosity, and viscoelastic stability comparable to whipped animal cream formulations. These findings provide a new idea for the application of Nano-CF/KGM composite gels in whipped cream.

Microstructural studies of imitation cheese with a shift in continuous phase

When casein is replaced with starch in imitation cheese, the functionality changes. Three different microscopy methods were applied to understand the microstructural differences in the product depending on which component dominates the microstructure. Confocal Laser Scanning Microscopy (CLSM) for component identification. Scanning Electron Microscopy (SEM) and Cryogenic Scanning Electron Microscopy (Cryo-SEM) for studying surface structures. Differences in the surface structures were detected between SEM and Cryo-SEM. In SEM, starch appeared rough and protein smooth, while in Cryo-SEM no starch roughness of the surface was found. A change in starch modification and effects of protein prehydration was also analysed. Adding octenyl succinic anhydride (OSA) modified starch for emulsifying properties resulted in a microstructure with fragmented protein at a protein level of 7 %, but not at 9 or 12 %. Protein prehydration had limited effect on microstructure. On a macrostructural level, the change to an emulsifying starch increased hardness in imitation cheese with 7 and 9 % protein. Protein prehydration slightly decreased the hardness, but the difference was not significant at all concentrations. This research provides valuable information about the microstructure of imitation cheese at a 50/50 composition, how the microstructure changes with an emulsifying starch and what occurs after a protein prehydration was included in the production.

The addition of resistant starch and protein to the batter reduces oil uptake and improves the quality of the fried batter-coated nuts

The batter compositions can affect the oil uptake and texture of fried batter-coated nuts. In this study, the oil uptake and quality of fried batter-coated peanuts and sunflower seeds added with resistant starch and protein were investigated. The results demonstrated that the addition of resistant starch increased the batter hardness and fracturability of the fried batter-coated peanuts by 34.36 % and 33.73 %, respectively. The oil content of fried batter-coated peanuts and sunflower seeds were decreased by 17.98 % and 15.69 %, respectively, with the addition of protein. The microstructure and roughness of the batter revealed that the batter added with protein became denser and uniform. Furthermore, the protein in the batter added with 6 % soy protein isolate had a high surface hydrophobicity. In summary, the addition of resistant starch and protein in batter will be a promising strategy for reducing the oil content and improving the quality of fried batter-coated nuts.

Modulation of starch structure, swallowability and digestibility of 3D-printed diabetic-friendly food for the elderly by dry heating

Elderly people often experience difficulty in swallowing and have impaired regulation of the nervous system. Furthermore, their blood glucose level can rise easily after eating. Therefore, functional foods that are easy to swallow and can maintain blood glucose at a lower level have been an important research topic in recent years. In this study, 3D printing was combined with dry heating to modify the starch in white quinoa and brown rice to develop whole grain foods with Osmanthus flavor that meet the dietary habits of the elderly. The samples were tested for printability, swallowing performance, and in vitro digestion. The results showed that after dry heating, all samples had shear-thinning properties and could pass through the extrusion nozzle of the printer smoothly. Both white quinoa and brown rice showed improved printability and self-support compared to the control. B45 (white quinoa, dry heating for 45 min) and C45 (brown rice, dry heating for 45 min) had significant elasticity and greater internal interaction strength during swallowing to resist disintegration of food particles during chewing. B45, C30, and C45, conformed to class 4 consistency and were characterized by easy swallowing of the diet. Further, dry heating resulted in greater resistance to enzymatic degradation of white quinoa and brown rice starch, with overall in vitro digestibility lower than the control.

Assembly of soy protein-corn starch composite gels by thermal induction: Structure, and properties

The effect of different corn starch (CS) concentrations on the gel formation of soybean isolate protein (SPI) was investigated. Moreover, the texture, rheological properties of the gel were determined, and the spatial structure and interactions of the composite gel system were analyzed. The composite system transitioned from liquid to solid-like with an increase in the CS concentration and did not backflow when inverted for 24 h. With the addition of CS, the gel strength, water holding capacity (WHC), G', and G'' increased significantly. The maximum was reached at 10 % starch concentration with gel strength of (228.96 ± 29.86) g and WHC of (98.93 ± 2.02)  %. According to low-field 1H nuclear magnetic resonance (LF-NMR) results, CS has a high water absorption capacity, which improved the WHC. The scanning electron microscopy results revealed that composite gels with a high CS concentration had a more dense and small void network structure. According to the results of molecular force interaction, infrared spectroscopy, Raman spectroscopy, and free sulfhydryl group analysis, the added starch promoted the unfolding of SPI molecules, exposure of hydrophobic groups, transformation of free sulfhydryl groups into disulfide bonds, and hydrogen bond formation. Hydrophobic interactions, disulfide bonding, and hydrogen bonding function together to form the SPI-CS composite gel system. The study results provide the basis for applying soy protein and CS gels.

Formulation and characterization of 3D printed chickpea protein isolate-mixed cereal dysphagia diet

The feasibility study of making 3D printed dysphagia diet was undertaken. A mixture of corn flour and buckwheat flour was used as the model cereal and chickpea protein isolate (CPI) was used as the model protein. Printing gels (inks) of the mixed cereal (control) and CPI-cereal mixture were produced by heating the formulations at 95 °C for 30 min and then cooling them to room temperature. The results showed that all the ink formulations containing CPI had higher apparent viscosity, preferable shear thinning behavior and shape supporting characteristics than that of the control. The cohesiveness and shape supporting ability of 10%CPI-cereal and 20%CPI-cereal formulations were poor and could not produce stable printing shape. The 30%CPI-cereal and 40%CPI-cereal formulations had suitable apparent viscosity, shear thinning behavior, storage modulus, yield stress and printing accuracy and the 3D printed products were stable. The control ink and 10%CPI-cereal ink had low cohesion and also could not pass the spoon tilt test. The 50%CPI-cereal formulation had high hardness and also could not pass the fork pressing test. The 30 % to 40 % CPI-cereal formulations were found to be suitable as dysphagia products as they could be classified as level 5 dysphagia diet.

Improvement of kefir fermentation on rheological and microstructural properties of soy protein isolate gels

Soy protein isolate (SPI) has become a promising plant-based material as an animal protein products alternative. However, its application was limited due to the weak gelling properties. To investigate the effect of kefir fermentation on SPI gels properties, SPI-polysaccharide gels was produced by unfermented and kefir-fermented SPI using different concentration of KGM, chitosan, and calcium chloride in this study. Characterization of fermented SPI gels showed that fermentation by kefir grains can be applied to improve the textural strength, mechanical structure, and thermal characteristics of SPI gels. Compared to unfermented SPI gels, the water-holding capacity was remarkably enhanced to 63.11% and 65.71% in fermented SPI-chitosan gels. Moreover, the hardness of fermented SPI-KGM gels were significantly increased to 13.43 g and 27.11 g. And the cohesiveness and resilience of fermented-KGM gels were also improved than unfermented samples. Results of rheological characterization and thermogravimetric analysis revealed the strengthened mechanical features and higher thermal stability of fermented SPI gels. Additionally, the main role of hydrophobic interactions and secondary structure variations of SPI gels were demonstrated by intermolecular force measurements, Fourier-transform infrared spectroscopy, and X-ray diffraction. Moreover, the network structure was observed more compact and homogeneous performed by microstructural images in fermented SPI gels. Therefore, this research provided a novel approach combining multi-species fermentation with protein gelation to prepare SPI gel materials with improved nutrition and structural properties.

Effect and Mechanism of Soluble Starch on Bovine Serum Albumin Cold-Set Gel Induced by Microbial Transglutaminase: A Significantly Improved Carrier for Active Substances

Soluble starch (SS) could significantly accelerate the process of bovine serum albumin (BSA) cold-set gelation by glucono-δ-lactone (GDL) and microbial transglutaminase (MTGase) coupling inducers, and enhance the mechanical properties. Hardness, WHC, loss modulus (G″) and storage modulus (G') of the gel increased significantly, along with the addition of SS, and gelation time was also shortened from 41 min (SS free) to 9 min (containing 4.0% SS); the microstructure also became more and more dense. The results from FTIR, fluorescence quenching and circular dichroism (CD) suggested that SS could bind to BSA to form their composites, and the hydrogen bond was probably the dominant force. Moreover, the ability of SS to bind the original free water in BSA gel was relatively strong, thereby indirectly increasing the concentration of BSA and improving the texture properties of the gel. The acceleration of gelling could also be attributed to the fact that SS reduced the negative charge of BSA aggregates and further promoted the rapid formation of the gel. The embedding efficiency (EE) of quercetin in BSA-SS cold-set gel increased from 68.3% (SS free) to 87.45% (containing 4.0% SS), and a controlled-released effect was detected by simulated gastrointestinal digestion tests. The work could put forward new insights into protein gelation accelerated by polysaccharide, and provide a candidate for the structural design of new products in the food and pharmaceutical fields.

Multifunctional acetylated distarch phosphate based conducting hydrogel with high stretchability, ultralow hysteresis and fast response for wearable strain sensors

The rapid development of flexible sensors has greatly increased the demand for high-performance hydrogels. However, it remains a challenge to fabricate flexible hydrogel sensors with high stretching, low hysteresis, excellent adhesion, good conductivity, sensing characteristics and bacteriostatic function in a simple way. Herein, a highly conducting double network hydrogel is presented by incorporating lithium chloride (LiCl) into the hydrogel consisting of poly (2-acrylamide-2-methylpropanesulfonic acid/acrylamide/acrylic acid) (3A) network and acetylated distarch phosphate (ADSP). The addition of ADSP not only formed hydrogen bonds with 3A to improve the toughness of the hydrogel but also plays the role of "physical cross-linking" in 3A by "anchoring" the polymer molecular chains together. Tuning the composition of the hydrogel allows the attainment of the best functions, such as high stretchability (∼770 %), ultralow hysteresis (2.2 %, ε = 100 %), excellent electrical conductivity (2.9 S/m), strain sensitivity (GF = 3.0 at 200-500 % strain) and fast response (96 ms). Based on the above performance, the 3A/ADSP/LiCl hydrogel strain sensor can repeatedly and stably detect and monitor large-scale human movements and subtle sensing signals. In addition, the 3A/ADSP/LiCl hydrogel shows a good biocompatibility and bacteriostatic ability. This work provides an effective strategy for constructing the conductive hydrogels for wearable devices and flexible sensors.

Impact of pH on pea protein-hydroxypropyl starch hydrogel based on interpenetrating network and its application in 3D-printing

Improving the mechanical and 3D printing performance of pea protein (PeaP) hydrogels contributes to the development of innovative plant-based gel products. Herein, we proposed a strategy for constructing PeaP-hydroxypropyl starch (HPS) interpenetrating network hydrogels, in which the structure, strength, and 3D printing properties of the hydrogels were regulated by changing pH. Results showed that pH significantly affected the gelation process of PeaP/HPS hydrogels. The hydrogels formed a lamellar structure at pH 3, a granule aggregation network structure at pH 5, porous structures at pH 7 and 9, and a honeycomb structure at pH 11. The strength of hydrogels formed at different pH values had the following order: pH 3 ＞pH 11 ＞ pH 7 ＞pH 9 ＞pH 5. The storage modulus (G') of the hydrogel at pH 3 was up to 4149 Pa, but only 695 Pa at pH 5. Moreover, hydrogel at pH 3 had the best self-recovery of 55%. 3D printed objects from gel inks at pH 3 exhibited high structural integrity and fidelity at 60 °C. Gelling force analysis indicated hydrogen bonds were the dominant interaction within all hydrogels. Overall, this study suggested that PeaP/HPS hydrogel formed at pH 3 possessed the most excellent mechanical properties and 3D printing capabilities, which may provide insights into the development of novel PeaP-based gel food ingredients and promote the application of PeaP in the food industry.

Characteristics of composite gels composed of citrus insoluble nanofiber and amylose and their potential to be used as fat replacers

Here, we prepared novel composite gels composed of citrus insoluble nanofiber and amylose, and examined their potential to be used as fat replacers and inhibit lipid digestion. We further evaluated the effect of different nanofiber/amylose ratios on the texture, thermal stability, water distribution, microstructure and lipid digestion of the composite gels. The addition of nanofiber improved the hardness, gumminess, viscoelasticity, thermal stability, and water-holding capacity of the composite gels, as well as strengthen their interpenetrating three-dimensional network. The gel prepared at a nanofiber/amylose ratio of 1:4 could provide an oral sensory perception similar to that of cream and therefore can be used as a potential fat replacer. Moreover, the emulsion stabilized by nanofiber/amylose could well inhibit lipid digestion, and the nanofiber/amylose ratio of 1:4 could achieve the minimum release amount of free fatty acids (55.81%). These findings provide a reference for the development of potential fat replacers.

Mechanical Properties, Microstructure, and In Vitro Digestion of Transglutaminase-Crosslinked Whey Protein and Potato Protein Hydrolysate Composite Gels

The production of animal protein usually leads to higher carbon emissions than that of plant protein. To reduce carbon emissions, the partial replacement of animal protein with plant protein has attracted extensive attention; however, little is known about using plant protein hydrolysates as a substitute. The potential application of 2 h-alcalase hydrolyzed potato protein hydrolysate (PPH) to displace whey protein isolate (WPI) during gel formation was demonstrated in this study. The effect of the ratios (8/5, 9/4, 10/3, 11/2, 12/1, and 13/0) of WPI to PPH on the mechanical properties, microstructure, and digestibility of composite WPI/PPH gels was investigated. Increasing the WPI ratio could improve the storage modulus (G') and loss modulus (G″) of composite gels. The springiness of gels with the WPH/PPH ratio of 10/3 and 8/5 was 0.82 and 0.36 times higher than that of the control (WPH/PPH ratio of 13/0) (p < 0.05). In contrast, the hardness of the control samples was 1.82 and 2.38 times higher than that of gels with the WPH/PPH ratio of 10/3 and 8/5 (p < 0.05). According to the International Organization for Standardization of Dysphagia Diet (IDDSI) testing, the composite gels belonged to food level 4 in the IDDSI framework. This suggested that composite gels could be acceptable to people with swallowing difficulties. Confocal laser scanning microscopy and scanning electron microscopy images illustrated that composite gels with a higher ratio of PPH displayed thicker gel skeletons and porous networks in the matrix. The water-holding capacity and swelling ratio of gels with the WPH/PPH ratio of 8/5 decreased by 12.4% and 40.8% when compared with the control (p < 0.05). Analysis of the swelling rate with the power law model indicated that water diffusion in composite gels belonged to non-Fickian transport. The results of amino acid release suggested that PPH improved the digestion of composite gels during the intestinal stage. The free amino group content of gels with the WPH/PPH ratio of 8/5 increased by 29.5% compared with the control (p < 0.05). Our results suggested that replacing WPI with PPH at the ratio of 8/5 could be the optimal selection for composite gels. The findings indicated that PPH could be used as a substitute for whey protein to develop new products for different consumers. Composite gels could deliver nutrients such as vitamins and minerals to develop snack foods for elders and children.

Effect of Soluble Dietary Fiber of Navel Orange Peel Prepared by Mixed Solid-State Fermentation on the Quality of Jelly

The aim of this work was to prepare soluble dietary fibers (SDFs) from insoluble dietary fiber of navel orange peel (NOP-IDF) by mixed solid-state fermentation (M-SDF) and to investigate the influence of fermentation modification on the structural and functional characteristics of SDF in comparison with untreated soluble dietary fiber (U-SDF) of NOP-IDF. Based on this, the contribution of two kinds of SDF to the texture and microstructure of jelly was further examined. The analysis of scanning electron microscopy indicated that M-SDF exhibited a loose structure. The analysis of scanning electron microscopy indicated that M-SDF exhibited a loose structure. In addition, M-SDF exhibited increased molecular weight and elevated thermal stability, and had significantly higher relative crystallinity than U-SDF. Fermentation modified the monosaccharide composition and ratio of SDF, as compared to U-SDF. The above results pointed out that the mixed solid-state fermentation contributed to alteration of the SDF structure. Furthermore, the water holding capacity and oil holding capacity of M-SDF were 5.68 ± 0.36 g/g and 5.04 ± 0.04 g/g, which were about six times and two times of U-SDF, respectively. Notably, the cholesterol adsorption capacity of M-SDF was highest at pH 7.0 (12.88 ± 0.15 g/g) and simultaneously exhibited better glucose adsorption capacity. In addition, jellies containing M-SDF exhibited a higher hardness of 751.15 than U-SDF, as well as better gumminess and chewiness. At the same time, the jelly added with M-SDF performed a homogeneous porous mesh structure, which contributed to keeping the texture of the jelly. In general, M-SDF displayed much excellent structural and functional properties, which could be utilized to develop functional food.

Understanding effects of glutelin on physicochemical and structural properties of extruded starch and the underlying mechanism

This work studied effects of different amounts of rice glutelin (RG) on physicochemical and structural properties of extruded rice starch (ERS) and explored the underlying mechanism of interaction between rice starch and RG upon extrusion processing. The results showed that the addition of RG altered the pasting properties, improved the viscoelastic, and increased the water mobility of ERS. The weight loss of ERS decreased from 71.40 % to 62.61 %, while the degradation temperature increased from 290.48 °C to 296.25 °C as the RG content increased from 0 % to 12 %. The complex index of extruded starch-glutelin complexes significantly elevated from 10.40 % to 35.81 % when RG content increased from 6 % to 12 %. Fourier-transform infrared spectra confirmed that RG interacted with starch via Maillard reactions, and the binding strength between RG and starch was enhanced at a higher RG content. Furthermore, results of rheological property and chemical interactions demonstrated that hydrogen bonding, hydrophobic, and electrostatic interaction were formed between RG and starch during extrusion. In summary, the obtained results of this study can further enrich the theory of starch-protein interactions and show the possibility of RG applied in the extruded starchy foods.

Rheological, textural, and water-immobilizing properties of mung bean starch and flaxseed protein composite gels as potential dysphagia food: The effect of Astragalus polysaccharide

The effects of Astragalus polysaccharide (APS) on rheological, textural, water-holding, and microstructural properties of mung bean starch (MBS)/flaxseed protein (FP) composite gels were investigated. Results showed that the storage modulus (G') of gels with APS were significantly lower than that of the control gel, while different concentrations of APS possessed diverse effects on the hardness, gumminess and cohesiveness of the gels. Adding APS significantly improved the water retention capacity by trapping more immobilized and free water in the gel network. Microstructurally, the MBS/FP/APS composite gels displayed a complex network with reduced pore size compared with that of the control gel (MBS/FP). International dysphagia diet standardization initiative (IDDSI) tests suggested that gels with APS contents below 0.09 % could be classified into level 6, while gel with 0.12 % APS could be categorized as level 7. Mechanistically, APS could influence the interactions between starch and protein within the tri-polymeric composite systems by affecting starch gelatinization and hydrogen bonding, further contributing to the formation of strengthened gel network and the change of gel properties. These results suggest that the macromolecular APS can improve the structural and textural properties of the starch-protein composite systems, and impart various functional properties to the FP-based gel foods.

pH-shifting alters textural, thermal, and microstructural properties of mung bean starch-flaxseed protein composite gels

The objective of this study was to investigate the effect of pH-shifting on the textural and microstructural properties of mung bean starch (MBS)-flaxseed protein (FP) composite gels. Results showed that different pH-shifting treatments caused changes in hydrogen bond interactions and secondary structures in composite gels, leading to the formation of loose or compact gel networks. The pH 2-shifting modified protein and starch molecules with shorter chains tended to form smaller intermolecular aggregates, resulting in the formation of a looser gel network. For pH 12-shifting treatment, conformational change of FP caused the unfolding of protein and the exposure of more hydrophobic groups, which enhanced the hydrogen bond and hydrophobic interactions between polymers, contributing to the formation of a compact gel network. Furthermore, pH 12-shifting improved the water-holding capacity (WHC), storage modulus, and strength of gels, while pH 2-treated gels exhibited lower WHC, hardness, and gumminess due to the degradation of MBS and denaturation of FP caused by extreme acid condition. These findings suggest that pH-shifting can alter the gel properties of bi-polymeric starch-protein composite systems by affecting the secondary structures of proteins and the hydrogen bonding between the polymers, and provide a promising way for a wide application of FP in soft gel-type food production.

Textural characterization of calcium salts-induced mung bean starch-flaxseed protein composite gels as dysphagia food

Effects of calcium gluconate (CG), calcium lactate (CL) and calcium dihydrogen phosphate (CDP) on the structural and functional properties of mung bean starch (MBS)-flaxseed protein (FP) composite gels were investigated to explore the feasibility of developing dysphagia food. The water-immobilizing, rheological and structural properties of MBS-FP composite gels adding different calcium salts (10, 30, and 50 mmol/L) were analyzed by low-field nuclear magnetic resonance measurement, rheological and textural analyses, fourier transform infrared spectroscopy, scanning electron microscopy and confocal laser scanning microscopy. Results showed that calcium salts imparted various soft gel properties to the composite gels by influencing the interactions between MBS and FP. Calcium salts could affect the conformation of amylose chains, accelerate the aggregation of FP molecules, and increase the cross-linking between starch and protein aggregates, resulting in the formation of large aggregates and a weak gel network. Consequently, calcium salts-induced composite gels showed lower viscoelastic moduli and gel strength than the control gel. In particular, different calcium salts had various impacts on the gel properties due to their diverse ability forming hydrogen bonds. Compared with CL and CDP, the gels containing CG presented the higher viscoelastic moduli and hardness, and possessed an irregular cellular network with the increased pore number and the decreased wall thickness. The gel containing 50 mmol/L CL had the highest water-holding capacity, in all the gels tested, by retaining more immobilized and mobile water in the compact gel network with larger cavities. The gels adding CDP presented lower hardness and gumminess due to the obvious lamellar structure within the network. International dysphagia diet standardization initiative (IDDSI) tests indicated that the gels adding CG and CL could be categorized into level 6 (soft and bite-sized) dysphagia diet, while the samples adding CDP could be classified into level 5 (minced and moist). These findings provide insights for the development of the novel soft gel-type dysphagia food.

Modification of starch by polysaccharides in pasting, rheology, texture and in vitro digestion: A review

Starch is a copolymer with unique physicochemical characteristics, is known for its low cost, easy degradability, renewable and easy availability. However, natural starches have some undesirable properties such as poor solubility, poor functional properties, lower resistant starch content with reduced retrogradation, and poor stability under various temperatures, pH, which limit their application in food. Different modification methods are used to improve its performance and expand its application. Numerous studies have been conducted to investigate why the addition of small amounts of polysaccharides affects the properties of starch pastes and gels. The application of polysaccharide-modified starch can be seen in the pasting, rheology, texture and in vitro digestive properties of starch gels. The main influencing factors include different starches, different specific polysaccharides, and different methods of preparation of composite pastes and gels. This paper reviews the changes in the properties of starch in terms of pasting, rheology, texture and in vitro digestion after modification with polysaccharides and the mechanism of polysaccharide action on starch.

Mimic Pork Rinds from Plant-Based Gel: The Influence of Sweet Potato Starch and Konjac Glucomannan

This study investigated the effect of sweet potato starch (SPS) and konjac glucomannan (KGM) on the textural, color, sensory, rheological properties, and microstructures of plant-based pork rinds. Plant-based gels were prepared using mixtures of soy protein isolate (SPI), soy oil, and NaHCO₃ supplemented with different SPS and KGM concentrations. The texture profile analysis (TPA) results indicated that the hardness, cohesiveness, and chewiness of the samples improved significantly after appropriate SPS and KGM addition. The results obtained via a colorimeter showed no significant differences were found in lightness (L*) between the samples and natural pork rinds after adjusting the SPS and KGM concentrations. Furthermore, the rheological results showed that adding SPS and KGM increased both the storage modulus (G’) and loss modulus (G’’), indicating a firmer gel structure. The images obtained via scanning electron microscopy (SEM) showed that the SPS and KGM contributed to the formation of a more compact gel structure. A mathematical model allowed for a more objective sensory evaluation, with the 40% SPS samples and the 0.4% KGM samples being considered the most similar to natural pork rinds, which provided a comparable texture, appearance, and mouthfeel. This study proposed a possible schematic model for the gelling mechanism of plant-based pork rinds: the three-dimensional network structures of the samples may result from the interaction between SPS, SPI, and soybean oil, while the addition of KGM and NaHCO₃ enabled a more stable gel structure.

A Relation between Exopolysaccharide from Lactic Acid Bacteria and Properties of Fermentation Induced Soybean Protein Gels

Exopolysaccharide (EPS) producing lactic acid bacteria (LAB) is considered to be an effective texture improver. The effect of LAB strains (different EPS production capacity) on physicochemical properties (texture profile, water distribution, rheological properties, and microstructure), protein conformation, and chemical forces of soybean protein gel was investigated. Correlations between EPS yield and gel properties were established. Large masses of EPS were isolated from L. casei fermentation gel (L. casei-G, 677.01 ± 19.82 mg/kg). Gel with the highest hardness (319.74 ± 9.98 g) and water holding capacity (WHC, 87.74 ± 2.00%) was also formed with L. casei. The conversion of β-sheet to α-helix, the increased hydrophobic interaction and ionic bond helped to form an ordered gel network. The yield was positively correlated with hardness, WHC, A₂₂, viscoelasticity, and viscosity, but negatively correlated with A₂₃ (p < 0.05). The macromolecular properties of EPS (especially the yield) and its incompatibility with proteins could be explained as the main reason for improving gel properties. In conclusion, the EPS producing LAB, especially L. casei used in our study, is the best ordinary coagulate replacement in soybean-based products.

Rheological and technological characterization of red rice modified starch and jaboticaba peel powder mixtures

Properties of modified starch and its interaction with functional raw materials are of great interest to the food industry. Thus, this study aimed to evaluate the rheological and technological characterization of starches modified by the action of the enzymes α-amylase and amyloglucosidase and their mixtures with jaboticaba peel powder. The parameters of firmness, gumminess, and final viscosity of starches paste increased, and the tendency to setback was reduced with the addition of jaboticaba peel powder. Starches and mixtures presented shear-thinning behavior. The addition of jaboticaba peel powder to starches increased water, oil, and milk absorption capacity, while syneresis remained stable over the storage period. The addition of jaboticaba peel powder had a positive effect on native and modified starches' rheological and technological properties, qualifying it as an alternative for developing new functional food products.