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In this study, the purpose was to investigate the effects with different concentrations of carrageenan (CG, 0–0.30%) on the gel properties and freeze–thaw stability of soy protein isolate (SPI, 8%) cold-set gels. LF-NMR, MRI, and rheology revealed that CG promoted the formation of SPI-CG cold-set gel dense three-dimensional network structures and increased gel network cross-linking sites. As visually demonstrated by microstructure observations, CG contributed to the formation of stable SPI-CG cold-set gels with uniform and compact network structures. The dense gel network formation was caused when the proportion of disulfide bonds in the intermolecular interaction of SPI-CG cold-set gels increased, and the particle size and zeta potential of SPI-CG aggregates increased. SG20 (0.20% CG) had the densest gel network in all samples. It effectively hindered the migration and flow of water, which decreased the damage of freezing to the gel network. Therefore, SG20 exhibited excellent gel strength, water holding capacity, freeze–thaw stability, and steaming stability. This was beneficial for the gel having a good quality after freeze–thaw, which provided a valuable reference for the development of freeze–thaw-resistant SPI cold-set gel products. [ABSTRACT FROM AUTHOR]

The changes of water-holding capacity, hardness, elasticity, soluble protein content, microscopic morphology and structure of soy protein isolate-dextran conjugate gels crosslinked by transglutaminase (TG) at different mass concen- tration(30,40,50,60 mg/mL) during freeze-thaw cycling (FTC) were explored. The Maillard reaction between soy protein isolate and dextran was confirmed by the results of SDS-PAGE electrophoresis. At the same time, soy protein isolate-dextran conjugates (SPI-D) were generated. With the Maillard reaction process proceeded, the grafting degree of SPI-D increased firstly and then decreased, finally reached the maximum of 12.54% at a mass concentration of 50 mg/mL. Surface hydrophobicity and fluorescence spectroscopy proved that the structure of the protein unfolded, flexibility and disorder enhanced, which was beneficial to the freeze-thaw stability. Compared with the control, the water-holding capacity of SPI-D, SPI and dextran mixture (SPI+D) and SPI gel decreased by 32.46%, 42.81% and 44.98%, the hardness in-creased by 124.66%, 271.51% and 343.38%, and the elasticity increased by 4.38%, 9.58% and 11.76%, the soluble protein content decreased by 2.05%, 3.61% and 7.17%, respectively, after 5 FTCs. Among these experimental groups, SPI-D gel showed the smallest change in all indicators and the best freeze-thaw stability, the microstructure of the gel was characterized by the scanning electron microscopy images, compared with SPI + D gel and SPI gel, SPI-D gel had smaller pores and more uniform organization. The above findings suggested that Maillard reaction was an effective technical means to enhance the freeze-thaw stability of soy protein isolate gel by enzyme method. [ABSTRACT FROM AUTHOR]

There is growing interest in enhancing the freeze–thaw stability of a Pickering emulsion to obtain a better taste in the frozen food field. A Pickering emulsion was prepared using a two-step homogenization method with soybean protein and maltose as raw materials. The outcomes showed that the freeze–thaw stability of the Pickering emulsion increased when prepared with an increase in soybean protein isolate (SPI) and maltose concentration. After three freeze–thaw treatments at 35 mg/mL, the Turbiscan Stability Index (TSI) value of the emulsion was the lowest. At this concentration, the surface hydrophobicity (H0) of the composite particles was 33.6 and the interfacial tension was 44.34 mN/m. Furthermore, the rheological nature of the emulsions proved that the apparent viscosity and viscoelasticity of Pickering emulsions grew with a growing oil phase volume fraction and concentration. The maximum value was reached in the case of the oil phase volume fraction of 50% at a concentration of 35 mg/mL, the apparent viscosity was 18 Pa·s, the storage modulus of the emulsion was 575 Pa, and the loss modulus was 152 Pa. This research is significant for the production of freeze–thaw resistant products, and improvement of protein-stabilized emulsion products with high freeze–thaw stability. [ABSTRACT FROM AUTHOR]

Pickering emulsions with good freeze-thaw stability are essential in frozen food applications. This study developed a high freeze-thaw stabilized soy protein isolate (SPI)-maltose (M) Pickering emulsion and applied it to frozen doughs to investigate and reveal its impacts on the processing properties of the frozen dough. The results showed that after the freeze-thaw cycle, with a volume ratio of 1:2 of SPI to M, the appropriate amount of M changed the structure of SPI. This resulted in the Pickering emulsion prepared by the SPI exhibiting the least droplet coalescence and the best freeze-thaw stability. The results of dough rheological properties, textural properties, and binding capacity with water demonstrated that Pickering emulsions effectively inhibited the loss of gluten protein network structure in the dough after freeze treatment and increased the binding capacity of gluten proteins with starch and water in the dough. The best results were obtained with the incorporation of 3 % SPI-M high freeze-thaw stability, where the amount of bound water following three freeze-thaw cycles was 4.27 times higher than in doughs without Pickering emulsion. Overall, this study is significant for enhancing the freeze-thaw stability of Pickering emulsions stabilized by proteins and providing a new application route for Pickering emulsions. [Display omitted] • Soybean isolate protein-maltose stabilized Pickering emulsion with a 1:2 volume ratio have excellent high freeze-thaw stability. • Highly freeze-thaw stable Pickering emulsions improve the processing characteristics of dough during freezing cycles. • Preparation of SPI-M particles by Glycosylation reaction. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • One-step fabrication of double network emulsion gels through heat treatment and ionic cross-linking. • The addition of sodium alginate led to increased hydrophobicity and changes in the secondary structure of soybean protein isolate. • Various concentrations of sodium alginate significantly affected the emulsion gel microstructure. • Soybean protein isolate-sodium alginate emulsion gels exhibited favorable texture and freeze-thaw stability. [ABSTRACT FROM AUTHOR]

Although emulsion gels show significant potential as fat substitutes, they are vulnerable to degreasing, delamination, and other undesirable processes during freezing, storage, and thawing, leading to commercial value loss in terms of juiciness, flavor, and texture. This study investigated the gel strength and freeze-thaw stability of soybean protein isolate (SPI)/curdlan (CL) composite emulsion gels after adding sodium chloride (NaCl). Analysis revealed that adding low salt ion concentrations promoted the hardness and water-holding capacity (WHC) of fat substitutes, while high levels displayed an inhibitory effect. With 40 mM NaCl as the optimum concentration, the hardness increased from 259.33 g (0 mM) to 418.67 g, the WHC increased from 90.59 % to 93.18 %, exhibiting good freeze-thaw stability. Confocal laser scanning microscopy (CLSM) and particle size distribution were used to examine the impact of salt ion concentrations on protein particle aggregation and the damaging effect of freezing and thawing on the proteoglycan complex network structure. Fourier-transform infrared spectroscopy (FTIR) and protein solubility evaluation indicated that the composite gel network structure consisted of covalent contacts between the proteoglycan molecules and hydrogen bonds, playing a predominant role in non-covalent interaction. This study showed that the salt ion concentration in the emulsion gel affected its molecular interactions. [Display omitted] • Freeze-thaw treatment caused fat substitute dehydration, oil loss, and instability. • Salt ions improved the fat substitute freeze-thaw stability. • Low NaCl concentrations promoted the fat substitute gel strength. • High NaCl concentrations inhibited the fat substitute gel strength. [ABSTRACT FROM AUTHOR]

All-natural plant protein-based high internal phase emulsion gels (HIPE-Gels) have attracted increasing attention recently in food, cosmetic, pharmaceutical, and other fields. Herein, HIPE-Gels were simultaneously fabricated by natural Quillaja saponin (QS) and soy protein isolate (SPI), and investigated the effects of environmental factors i.e. , storage, acidic, ionic strength, heating and freeze-thawing on their physical stability. The combination of SPI and QS enabled the highly stable O/W emulsion gels with a shear-thinning behavior. At the appropriate concentration (i.e. , 1.5% SPI and 0.09% QS), the emulsion gels exhibited high tolerance toward long-term storage and destabilizing environments. Although poor stability at a pH close to the isoelectric point of SPI, incorporating QS provided excellent acidic stability of plant-based emulsion gels. The strong electrostatic repulsion provided by QS would reduce the aggregation between droplets under acid environment and the electrostatic shielding of salt ions, improving the acid tolerance and salt tolerance of SPI-based emulsion gels. In addition, QS had also improved their thermal stability and freeze-thaw stability. These findings demonstrated that the combination of SPI and QS could provide an effective strategy to fabricate all-natural plant protein-based mayonnaise to withstand several environmental factors, developing label-friendly novel food products. [Display omitted] • All-natural plant-based HIPE-Gels simultaneously stabilized by Quillaja saponin (QS) and soy protein isolate (SPI). • Influence of environmental stresses (i.e. , storage, acidic, NaCl, thermal and freeze-thawing) on stability was systematically investigated. • HIPE-Gels simultaneously stabilized by SPI and QS showed a better physical stability. • These plant-based emulsifiers had synergistic effects on improving emulsion stability. • Providing important information about the formation of stable plant protein-based foods. [ABSTRACT FROM AUTHOR]

To improve the freeze‐thaw stability of rice starch (RS), the soybean protein hydrolysates (SPHs), xanthan gum (XG), and the blends of SPHs with XG (SPHs‐XG) are added. The syneresis, thermal, texture, rheological properties, and morphological features of samples during seven freeze‐thaw cycles (FTCs) are investigated by syneresis measurement, differential scanning calorimetry (DSC), textural properties analysis (TPA), dynamic rheological, NMR, and SEM. As a result, SPHs‐XG is more effective for improving the freeze‐thaw stability and showed improved structure manifestations with the lower retrogradation rate (22.78%), hardness (153.29 g), gumminess (54.57), and solid‐like structure (p < 0.05). Moreover, the water‐holding capacity is increased and the microstructure is effectively stabilized. All these results suggested that SPHs‐XG could be a potential ingredient to improve the quality of rice starch‐based frozen foods. [ABSTRACT FROM AUTHOR]

This study used Soy Protein Isolate (SPI), Soy Protein Isolate Hydrolysates (SPH) and Dextran (D) as raw materials. Covalent compounds were prepared by grafting soy protein isolate and soy protein isolate hydrolysate with dextran by water‐heating method, which were SPI‐D and SPH‐D, respectively. The effect of ionic strength (0–500 mM) on the freeze–thaw stability of SPI, SPI‐D, and SPH‐D emulsions was investigated. Fourier transform infrared analysis and Fluorescence emission spectroscopy analysis indicated that the structure of the protein changed. In this study, it was found that with the increase of ionic strength, the zeta potential of the three samples presented a downward trend and the surface hydrophobicity first decreased and then increased. The addition of ions effectively improved the freeze–thaw stability of the emulsions. The particle size of the emulsions changed little after freeze–thaw cycles, and coalescence degree, creaming index, and oiling off significantly decreased. Especially when the ionic strength reached 300 mM, the degree of coalescence was 248.46%, 170.92%, and 167.77%, respectively, and the oiling off was also reduced by 68.52%, 68.25%, and 59.92%, respectively. The creaming index of the SPI emulsion was 48.49% lower than the creaming index without ions. However, when the ionic strength exceeded 300 mM, the coalescence degree, creaming index, and oiling off of the emulsions increased. Optical microstructures also found that at ionic strength of 300 mM, the oil droplets produced by the three kinds of emulsion after freeze–thaw were smaller than those without ions. [ABSTRACT FROM AUTHOR]

In this study, soy protein isolate (SPI) and maltose (M) were employed as materials for the synthesis of a covalent compound denoted as SPI-M. The emulsion gel was prepared by transglutaminase (TGase) as catalyst, and its freeze-thaw stability was investigated. The occurrence of Maillard reaction was substantiated through SDS-PAGE. The analysis of spectroscopy showed that the structure of the modified protein was more stretched, changed in the direction of freeze-thaw stability. After three freeze-thaw cycles (FTC), it was observed that the water holding capacity of SPI-M, SPI/M mixture (SPI+M) and SPI emulsion gels exhibited reductions of 8.49 %, 16.85 %, and 20.26 %, respectively. Moreover, the soluble protein content also diminished by 13.92 %, 23.43 %, and 35.31 %, respectively. In comparison to unmodified SPI, SPI-M exhibited increase in gel hardness by 160 %, while elasticity, viscosity, chewability, and cohesion demonstrated reductions of 17.7 %, 23.3 %, 33.3 %, and 6.76 %, respectively. Concurrently, the SPI-M emulsion gel exhibited the most rapid gel formation kinetics. After FTCs, the gel elastic modulus (G′) and viscosity modulus (G″) of SPI-M emulsion were the largest. DSC analysis underscored the more compact structure and heightened thermal stability of the SPI-M emulsion gel. SEM demonstrated that the SPI-M emulsion gel suffered the least damage following FTCs. • The covalent reaction between maltose and SPI made the protein changed in the direction of freeze-thaw stability. • Grafting with maltose can enhance the freeze-thaw resistance of emulsion gel. • Maillard reaction remarkably improved freeze-thaw stability and strength of emulsion gels. • Rheological tests demonstrated that the maltose access contributed to increased gel mechanical strength and formation. • SEM confirmed microstructure changes of SPI-M emulsion gels after freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

Pickering emulsions are of great interest to the food industry and their freeze-thaw stability important when used in frozen foods. Particles of soybean isolate (SPI) were heat treated and then crosslinked with transglutaminase (TG) enzyme to produce Pickering emulsions. The protein particles produced using unheated and uncrosslinked SPI (NSPI) was used as the benchmark. The mean particle size, absolute zeta potential, and surface hydrophobicity of protein particles produced using heat treatment and TG crosslinking (at 40 U/g) SPI (HSPI-TG-40) were the highest and substantially higher than those produced using NSPI. The thermal treatment of protein particles followed by crosslinking with TG enzyme improved the freeze-thaw stability of Pickering emulsions stabilized by them. The Pickering emulsions produced using HSPI-TG-40 had the lowest temperature for ice crystal formation and they had better freeze-thaw stability. The plant-based ice cream prepared by HSPI-TG-40 particle-stabilized Pickering emulsions had suitable texture and freeze-thaw stability compared to the ice cream produced using NSPI. The Pickering particles produced using heat treatment of SPI followed by crosslinking with TG (at 40 U/g) produced the most freeze-thaw stable Pickering emulsions. These Pickering particles and Pickering emulsions could be used in frozen foods such as ice cream. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the impact of ultrasonic modification at various ultrasonic power extents on the freeze-thaw stability of soy protein isolate (SPI) gel. The freeze-thaw stability of the gel was evaluated by examining the changes in texture, water holding capacity, microstructure and soluble protein content during the process of 5 freeze-thaw cycles. In addition, effects on particle size, surface hydrophobicity and structure were also explored. The results showed that within a certain range, the average particle size of the protein gradually decreased, and the particle size distribution was narrower with ultrasonic intensity, it may be due to the high shear and cavitation effects of sonication that reduce the degree of protein aggregation. Furthermore, we also detected that treated proteins had lower fluorescence intensity, higher surface hydrophobicity and more flexible molecular structure with the reduction of α-helical structure as well as the rise of random coil. In terms of gel freeze-thaw stability, moderate ultrasound treatment made the water holding capacity and soluble protein content of SPI gel reduce by 38.27% and 3.58%, whereas the hardness and elasticity increased by 510.23g and 0.06mm after 5 FTC. The corresponding changes of indexes of the control group were 75.05%, 51%, 1062.75g and 0.11mm, respectively. It can be observed that the change range of treated SPI gel properties was smaller than that of natural SPI gel, indicating that ultrasonic treatment can remarkably improve the freeze-thaw stability of the gel which might have something to do with changes of protein structure. [ABSTRACT FROM AUTHOR]

Protein hydrolysis on the freeze-thaw stability of emulsions prepared with soy protein - dextran conjugates were investigated. Soy protein isolate-dextran (SPI-D) and soy protein hydrolysates-dextran (SPH-D) conjugates with different degree of hydrolysis (DH) were formed by Maillard reaction. The formation of protein-polysaccharide conjugates between SPI/SPH and dextran molecules was confirmed by SDS-PAGE; this finding was consistent with the degree of glycation and the browning index. The freezethaw emulsion stability was investigated. The results confirmed that the SPH3-D (DH at 3%) emulsion with 3% DH of SPI exhibited the lowest creaming index after experiencing 1, 2, and 3 freeze-thaw cycles, with results of 7.69%, 20.74% and 31.30%, respectively. The SPH3-D emulsion had a significantly lower average particle size, which was reduced by 48.28% compared to the SPI-D emulsion. Meanwhile, the SPH3-D solution had low interfacial tension. The confocal laser scanning microscopy analysis indicated that the SPH3-D emulsions were strongly stable against the freeze-thaw treatment and could be used as effective emulsifiers in frozen foods. [ABSTRACT FROM AUTHOR]

Abstract Oil-in-water (o/w) emulsions stabilized by soybean protein isolate (SPI) and enzyme-modified soybean protein isolate (SPI + TGase, SPIH, SPIH + TGase) were subjected to three freeze-thaw cycles, and changes in the molecular weight distribution, secondary structure contents, particle size, oiling off (OF), creaming index (CI) and microstructures were investigated. The emulsions exhibited different freeze-thaw tolerance stabilities, which were dependent on the type of enzyme used to prepare the SPI as well as the cycle number of freeze-thaw treatments. Differential scanning calorimetry suggested that emulsion destabilization was mainly due to water crystallization. After three freeze-thaw cycles, the emulsion stabilized by SPIH + TGase showed a decrease of 78.89% in CI and 72.35% in OF compared with SPI. Correspondingly, the particle size decreased by 70.76% (in water) and 88.99% (in 1% SDS). The improvement in the freeze-thaw stability could be largely attributed to the increased molecular flexibility due to the increased α-helix and random coil contents after enzymatic hydrolysis and the formation of gel-like network structures after the addition of TGase cross-linking. The observation of the microstructure also indicated that SPIH + TGase was an effective food emulsifier. These findings could be of great importance for the formulation of food grade emulsions with excellent freeze-thaw stability. Highlights • Freeze-thaw stabilization of SPI, SPIH, SPI + TGase, SPIH + TGase was studied. • Different modification methods and freeze-thaw cycles were investigated. • ζ-potential, particle size, microstructure, OF and CI reflect the stability. • SPIH + TGase can effectively improve the freeze-thaw stability of the emulsion. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of pH on the freeze-thaw stability of glycated soy protein isolate (SPI) and soy protein isolate hydrolysate (SPH) were studied. The covalent compounds were prepared by conjugating SPI, SPH and dextran under heated Maillard reaction, which the macromolecules were named SPI-D and SPH-D. SDS-PAGE analysis verified that SPI-D and SPH-D form a covalent bond through the Maillard reaction. Afterwards, the effects of pH on the freeze-thaw stability of SPI, SPI-D and SPH-D emulsions were evaluated. The covalent conjugate stabilized emulsions improved the stability of the emulsions to pH stress. After freeze-thaw cycles, SPH-D revealed the lowest particle size, degree of coalescence (CD) and oiling off. The results above were also supported by optical microscopy analysis. [ABSTRACT FROM AUTHOR]

Abstract There is increasing interest in improving the freeze-thaw stability of emulsions by interfacial engineering in the food colloid field. The present work reported that for Pickering emulsions stabilized by heat-induced soy protein isolate (SPI) nanoparticles, their freeze-thaw stability could be well modulated by modifying the characteristics of the nanoparticles. The SPI nanoparticles with different characteristics (e.g., particle size, surface hydrophobicity) were obtained by heating the SPI solutions at initial concentrations (c i) of 0.25–6.0 wt% at 95 °C for 15 min. All the initial Pickering emulsions were formed at an oil fraction of 0.4 and protein concentration of 0.25 wt% in the aqueous phase, in the presence of 300 mM NaCl. In general, increasing the c i resulted in a progressive enhancement in freeze-thaw stability of the emulsions against creaming and coalescence, but accelerated the flocculation. The higher creaming stability at higher c i values seemed to be closely associated with the enhanced coalescence stability, as well as the strengthened gel-like network of these initial emulsions. There were close interplays between the freeze-thaw stability and the properties of the initial emulsions, or characteristics (e.g. particle size or surface hydrophobicity) of heat-induced SPI nanoparticles. The results confirmed that the SPI nanoparticles with larger sizes, higher surface hydrophobicity and more efficient packing at interface exhibit a greater potential to produce Pickering emulsions with higher freeze-thaw stability. The findings would be of relevance for understanding the freeze-thaw stability of Pickering emulsions stabilized by protein-based particles, as well as for the development of protein-stabilized emulsion formulations with a high freeze-thaw stability. Graphical abstract Image Highlights • Different SPI nanoparticles were fabricated by heating SPI solutions at different concentrations (c i). • Increasing the c i resulted in a gradual increase in particle size and surface hydrophobicity. • The freeze-thaw stability of the emulsions against creaming and coalescence inreased with the c i. • Close relationships between the particle characteristics and freeze-thaw stability of the emulsions were observed. • The gel-like network formation also contributed to the freeze-thaw stability. [ABSTRACT FROM AUTHOR]

Animal or plant-based meat products are typically stored and transported using freezing. Freezing-thawing cycles can lead to detrimental changes in the texture, appearance, and mouthfeel of fat substitutes, thus affecting their quality. In this work, a protein/polysaccharide composite emulsion gel was created by emulsifying soybean isolate protein (SPI) and palm oil (PO), and incorporating curdlan (CL). It can serve as a potential replacement for animal fat in meat products, such as sausage, and plant-based meat. The study aimed to investigate the stability of the complex fat substitutes during freeze-thaw at various melting points and palm oil content. The results showed that the 52°C-palm oil samples were the most freeze-thaw stable compared to samples with other melting points. 52°C-palm oil samples were tested for texture and water holding capacity (WHC), increasing the oil content from 5g/100g–20g/100g improved the gel strength and WHC after freeze-thaw. The samples containing high melting point palm oil were less affected by temperature changes and showed higher stability as detected by low-field NMR and differential calorimetric scanning. The confocal laser scanning and rheological detection further confirmed the enhanced structural strength and freeze-thaw stability of the emulsion gels containing solid fat particles with high melting points. • Freeze-thaw treatment causes fat substitutes to syneresis and lose oil, creating folds and pores. • Increased content of low melting point oil will destroy the structure of emulsion gel. • High melting point oil will improve the strength and water holding capacity of the emulsion gel. • High melting point palm oil improves freeze-thaw stability of fat substitutes. [ABSTRACT FROM AUTHOR]

The investigation of limited hydrolysis combined with Maillard-induced glycation on improving the freeze-thaw stability of soy protein isolate (SPI) was carried out. Soy protein isolate hydrolysate (SPH) was first prepared by trypsin, with a hydrolysis degree of 2% and 5%. Afterwards, SPI and SPH were conjugated with dextran to form a covalent complex macromolecule, which were named SPI-D, SPH2-D and SPH5-D, respectively. Covalent bond was formed between SPI/SPH and dextran molecules via the glycation reaction has been confirmed by fourier transform infrared (FTIR) spectroscopy analysis. Subsequently, the freeze-thaw stability of SPI-D and SPH-D was evaluated. After three freeze-thaw cycles, the characters of SPH-D emulsions exhibited smaller values than those of SPI-D emulsions in terms of oiling off, particle size, flocculation degree (FD) and coalescence degree (CD). In addition, SPH2-D emulsions were more stable after freeze-thaw treatment compared with SPH5-D emulsions. Optical microscopy analysis also supported the results above. [ABSTRACT FROM AUTHOR]

There is still a debate about the influence of salts on the freeze-thaw stability of emulsions. In this research, the influence of the NaCl addition (before or after the emulsification; 100–500 mM) on the freeze-thaw stability of the Pickering emulsions stabilized by heat-induced soy protein isolate (SPI) nanoparticles, at a given protein concentration of 1.0% (w/v) and oil fraction of 0.4, was investigated. The addition of NaCl resulted in considerable changes in particle characteristics (including particle size, surface hydrophobicity and ζ -potential) of the SPI nanoparticles, with the extent of the changes varying with the applied ionic strength ( μ ). Despite the NaCl addition before or after the emulsification, the presence of NaCl remarkably improved the freeze-thaw stability against droplet coalescence and creaming of the emulsions, though the improvement was related to the applied μ . The improvement of the freeze-thaw stability would be largely attributed to the strengthening of the interfacial protein or protein nanoparticle films coating droplets, rather than the inhibition of ice crystal formation by the presence of NaCl. If the salt was introduced before the emulsification, a gel-like network might be formed in the corresponding emulsions, which would further provide an additional stabilization against the freeze-thaw treatment. Optimal freeze-thaw stability was observed in the presence of appropriate concentrations of NaCl (e.g., 100–200 mM). This is the first report to indicate the importance of the electrostatic screening to the improvement of the Pickering emulsions stabilized by charged particles. The findings would be of great importance for the formulation of food grade emulsions with excellent freeze-thaw stability. [ABSTRACT FROM AUTHOR]

The freeze-thaw stability of Pickering emulsions stabilized by (nano)particles from heated soy protein isolate (SPI) and whey protein (WP), was investigated and compared with those stabilized by unheated SPI (or WP) and sodium caseinate (NaCN). The stability was evaluated in terms of flocculation and coalescence degrees, and creaming index, as well as differential scanning calorimetry (DSC) characteristics. The emulsions exhibited different patterns of freeze-thaw stability, depending on the type of applied proteins, as well as the cycle number of freeze-thaw treatment. In general, the emulsions stabilized by heated SPI and WP exhibited much better freeze-thaw stability against coalescence and creaming, than those by unheated counterparts. The freeze-thaw stability against creaming of the heated SPI emulsion was even much better than that of the NaCN emulsion. The emulsions stabilized by SPI or WP, unheated or heated, showed poor freeze-thaw stability against flocculation. The differences in freeze-thaw stability between different emulsions could be explained in terms of the differences in physicochemical parameters of proteins or protein particles, as well as their microstructure. The good freeze-thaw stability of the emulsions by heated SPI and WP might be largely due to the action of Pickering steric stabilization, while the gel-like network formation also attributed to the stability. The results would be of great importance for the fabrication of Pickering emulsions stabilized by food protein particles and their applications in food formulations. [ABSTRACT FROM AUTHOR]

The soy protein isolate-dextran (SPI-D) conjugates were prepared by ultrasound (power output 500 W for 40 min) and microwave (power output 800 W for 2 min) assisted glycosylation to improve the freeze-thaw stability of soy protein isolate stabilized oil-in-water (o/w) emulsions. Fourier transform infrared and fluorescence emission spectroscopy analyses confirmed that covalent bonds were formed between soy protein isolate (SPI) and dextran molecules through the Maillard reaction. The stability of SPI, SPI+D mixture, ultrasound SPI-D conjugates (SPI-D U ) and microwave SPI-D conjugates (SPI-D M ) emulsions subjected to from one to three freeze-thaw cycles was investigated. In comparison with SPI and SPI+D emulsions, SPI-D U and SPI-D M emulsions exhibited smaller creaming index, oiling off, droplet diameters, flocculation degree (FD) and coalescence degree (CD) after each freeze-thaw cycle. In addition, the zeta potential and specific surface area (SSA) were greater. Appearance and microstructure indicated that SPI-D U and SPI-D M emulsions exhibited a relative stable state after three freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

The freeze-thaw stability of oil-in-water emulsions prepared with unheated and heated aqueous dispersions of fresh and stored soy protein isolates was evaluated in the absence and presence of glucose or sorbitol (0.75–15.0% w/w). Sample aging had a negative impact of freeze-thaw stability. The cryoprotectant addition enhanced the freeze-thaw stability, but at low concentrations emulsions prepared with unheated soy protein isolates showed better response to freeze-thawing. Nevertheless, at the highest cryoprotectant concentration, a total stabilization was evidenced for all emulsions. The results of this article indicated that the cryoprotectants act on proteins at interfacial level. [ABSTRACT FROM PUBLISHER]

We demonstrated soy protein isolate (SPI) at pH 3 is suitable for preparing edible HIPEs with internal phase of corn oil, even at protein concentration as low as 0.5% (w/v). The highest internal phase volume reached 90% (v/v). There was no remarkable difference in appearance of the HIPEs after heating, but phase separation happened after freeze-thaw treatment. Interestingly, no distinct difference can be found in appearance of the heated HIPEs with internal phase volumes of 85% and 90% after freeze-thawing thrice. All the HIPEs exhibit a solid-like behavior as revealed by the results that the G′ value was higher than G′′ value. The increased surface hydrophobicity after heating suggested interaction of protein can happen after emulsion heating. The confocal laser scanning microscope confirmed the interaction of SPI and emulsions. The HIPEs can be utilized to encapsulate β-carotene. The β-carotene retention in HIPEs was 74.1%, significantly higher than that in corn oil. • SPI at pH 3 is able to stabilize HIPEs with internal phase volume up to 90%. • Heating significantly improved the freeze-thaw stability of SPI-stabilized HIPEs. • Protein interaction is responsible for the improved stability of HIPEs after heating. • β-Carotene stability was enhanced after encapsulation in the SPI-stabilized HIPEs. [ABSTRACT FROM AUTHOR]

This article focused on the freeze-thaw stability and rheological properties of soy protein isolate (SPI) emulsion gels induced by NaCl. The freeze-thaw stability was characterized by particle size, ζ-potential, and differential scanning calorimetry (DSC) measurements. The salt concentration (200–400 mM) could promote protein aggregation and improve freeze-thaw stability. The study of both linear and nonlinear rheology properties proved that SPI emulsion gels exhibited the maximal gel strength at 300 mM NaCl that could resist structure disruption and oil droplet migration. The nonlinear responses were further analyzed using Lissajous plots. Initial SPI emulsion gels had higher peak stress values at 300 mM NaCl, indicating more resistance to deformation and increased elastic-dominant behavior as well as improved freeze-thaw stability. While the area of the elastic and viscous Lissajous plots narrowed as the salt concentration exceeded 300 mM, suggesting the viscosity and elasticity decreased. Scanning electron microscopy (SEM) images further confirmed that the SPI emulsion gels had smaller pores and denser structures at 300 mM NaCl, resulting in good freeze-thaw stability. Besides, the maximum gel strength emerged in 300 mM NaCl and 100 mM NaCl before and after freeze-thaw cycles, respectively, which was due to moderate dehydration and a small amount of oil leakage from the network. These findings provide valuable information for the relationships between freeze-thaw stability and rheology property of emulsion gels. [Display omitted] • The presence of NaCl remarkably improved freeze-thaw stability and strength of emulsion gels. • At 200–400 mM NaCl, no coalescence was observed after freeze-thaw cycles. • SPI emulsion gels had the maximal peak stress and gel strength at 300 mM NaCl. • The gel strength changed after freeze-thaw cycles due to dehydration. • LAOS rheology confirmed microstructure changes of SPI emulsion gels after freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of freeze-thaw treatment on the structure and texture of transglutaminase crosslinked soy protein isolate gels with glycated modifications. Different mass ratios (1:1, 2:1, 3:1 and 4:1) of a soy protein isolate/dextran mixture (SPI + D) and the structural properties and gel texture of a soy protein isolate-dextran conjugate (SPI-D) were investigated. The results showed that the degree of grafting increased with increasing dextran content and was maximized when SPI:D was 1:1 (16.51%). The SDS-PAGE results showed that the glycation reaction generated glycoprotein. Fluorescence spectroscopy and surface hydrophobicity results confirmed the change in the structure of the soy protein isolate. The SPI-D (2:1) gel exhibited the highest water holding capacity, with values of 90.33%, 68.67%, 60.11% and 58.49% at 0, 1, 3 and 5 freeze-thaw cycles (FTCs), respectively. Scanning electron microscopy results showed that the structure of the SPI-D gel was uniform and more regular after being subjected to FTCs. The hardness and gumminess of all experimental groups increased with the increasing number of FTCs. Glycation could reduce the degree of SPI gel soluble protein reduction during freezing and thawing. - Glycosylation reduces the adverse effect of freeze-thaw treatment on the formation of SPI gel. - The freeze-thaw treatment resulted in a rough network structure in the composite gels. - Soy protein isolate-dextran conjugate gel was uniform and more regular after freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

For the first time, the irradiation technology combined with Maillard reaction were used to improve the freeze - thaw stability of soybean protein emulsion. The freeze-thaw stability of emulsions prepared with soy protein isolate (SPI), soy protein isolate and maltose mixture (SPI + M) or glycosylated soy protein isolate with maltose formed by irradiation of 7.5 kGy and 12.5 kGy (named SPI-M 7.5 and SPI-M 12.5 , respectively) was compared. Fourier transform infrared spectroscopy, fluorescence spectroscopy and ultraviolet spectroscopy confirmed the change of the structure of soy protein isolate, indicating that maltose was covalently linked to soybean protein isolate. Scanning electron microscopy showed that the modified protein particles were more loose, uniform in size, and significantly reduced in molecular aggregation than untreated protein. The freeze-thaw stability of SPI, SPI + M, and SPI-M 7.5 and SPI-M 12.5 emulsions was evaluated. It was found that after three freeze-thaw cycles, the creaming index, oiling off, particle size, coalescence degree and flocculation degree of emulsions prepared with irradiated SPI samples were all lower than those prepared with SPI and SPI + M. Zeta potential, laser confocal and optical microscopy showed that the emulsion was still in a relatively stable state, and the SPI-M 7.5 emulsion after freeze-thaw treatment was more stable than the SPI-M 12.5 emulsion. Image 10726 • For the first time, the irradiation technology was used to promote Maillard reaction. • The irradiated glycosylated soy emulsion could be used as the effective stabilizer. • The SPI-M 7.5 emulsion was more stable than the SPI-M 12.5 emulsion after freeze-thaw treatment. • This study could promote the practical application of irradiation technology and Maillard reaction in SPI modification. [ABSTRACT FROM AUTHOR]