Improvement of gelation properties of silver carp surimi through ultrasound-assisted water bath heating

The present work investigated the effects of water bath heating coupled with different ultrasound treatments on the gel properties, protein conformation, microstructures and chemical interactions of silver carp surimi at low/high salt levels. Results showed that the gel strength, hardness, springiness and water holding capacity (WHC) of surimi gels at low salt concentration were inferior to those at high salt content, regardless of the treatments. Compared with the traditional water bath heating, ultrasonic-assisted treatments significantly improved the gelation properties of surimi at the same salt level. In fact, ultrasound treatment also facilitated the unfolding of α-helix structure of the protein, with the resulting exposure of internal groups further enhancing hydrophobic interactions and hydrogen bonds between protein molecules, thereby leading to the formation of denser microstructures with smaller holes. Furthermore, the most noteworthy ultrasonic treatment group was ultrasound-assisted preheating (U + W) group, whose gelation performance under low salt condition, was comparable with that of the traditional two-stage heating (W + W) group with high salt content. Overall, ultrasound-assisted water bath preheating proved to be a feasible approach to improve the gel properties and microstructures of low-salt surimi gels.     

Ultrasound-assisted immersion freezing reduces the structure and gel property deterioration of myofibrillar protein from chicken breast

The effects of air freezing (AF), immersion freezing (IF) and ultrasound-assisted immersion freezing (UF) at different power levels (125, 165, 205 and 245 W) on the structure and gel properties of the myofibrillar protein (MP) of chicken breast were investigated. UF at 165 W (UF-165) had no obvious negative impact on the primary structure of the MP and effectively reduced the change in the secondary and tertiary structure. In addition, UF-165 significantly reduced the losses in the elastic modulus (G′), gel strength, and gel water holding capacity (P < 0.05). According to low field nuclear magnetic resonance analysis, the T₂₁ and T₂₂ of the UF-165 MP gels were shorter than those of the AF and IF samples, which meant that the UF-165 reduced the mobility of the immobilized water and free water in MP gel. A scanning electron microscopy analysis showed that the appropriate ultrasonic power promoted the formation of a compact and homogeneous protein gel network. These results suggested that the appropriate ultrasonic power maintained the MP structure and reduced the loss of gel quality.     

Physicochemical properties and microstructure of composite surimi gels: The effects of ultrasonic treatment and olive oil concentration

This study was conducted to evaluate the effects of extra virgin olive (EVO) oil incorporation on the physicochemical properties and microstructure of surimi gels subjected to ultrasound-assisted water-bath heating. As the oil content was increased from 0 to 5 g/100 g, the breaking force and gel strength of the surimi gels significantly decreased, while the whiteness level exhibited the opposite tendency irrespective of the heating method. Compared with the traditional water-bath heating method, the ultrasonic heating promoted the unfolding of the α-helix structure and intensified the formation of β-sheet content and non-covalent bonds (ionic bonds, hydrogen bonds, and disulfide bonds), especially disulfide bonds, which contributed to the further crosslinking of the proteins and to gelation, thereby improving the gels’ strength. In addition, smaller cavities and compact microstructures were observed in the low-oil (≤3 g/100 g) surimi gels under ultrasonic treatment, which effectively prevented water migration in the gel network and resulted in a high water holding capacity and uniform water distribution. However, the ultrasonic treatment barely remedied the poor microstructures of the high-oil (>3 g/100 g) surimi gels owing to oil coalescence, which weakened the protein–protein interaction. In conclusion, ultrasonic treatment combined with water-bath heating significantly improved the gelation properties of the low-oil surimi gels, although it did not remarkably improve those of the high-oil gels. The choice of a suitable oil concentration could be of great importance for the production and functioning of surimi products via ultrasound-assisted treatments.     

Improving the gel properties of salted egg white/cooked soybean protein isolate composite gels by ultrasound treatment: Study on the gelling properties and structure

In this study, the effects of ultrasound treatment on the texture, physicochemical properties and protein structure of composite gels prepared by salted egg white (SEW) and cooked soybean protein isolate (CSPI) at different ratios were investigated. With the increased SEW addition, the ζ-potential absolute values, soluble protein content, surface hydrophobicity and swelling ratio of composite gels showed overall declining trends (P < 0.05), while the free sulfhydryl (SH) contents and hardness of exhibited overall increasing trends (P < 0.05). Microstructural results revealed that composite gels exhibited denser structure with the increased SEW addition. After ultrasound treatment, the particle size of composite protein solutions significantly decreased (P < 0.05), and the free SH contents of ultrasound-treated composite gels were lower than that of untreated composite gels. Moreover, ultrasound treatment enhanced the hardness of composite gels, and promoted the conversion of free water into non-flowable water. However, when ultrasonic power exceeded 150 W, the hardness of composite gels could not be further enhanced. FTIR results indicated that ultrasound treatment facilitated the composite protein aggregates to form a more stable gel structure. The improvement of ultrasound treatment on the properties of composite gels was mainly by promoting the dissociation of protein aggregates, and the dissociated protein particles further interacted to form denser aggregates through disulfide bond, thus facilitating the crosslinking and reaggregation of protein aggregates to form denser gel structure. Overall, ultrasound treatment is an effective approach to improve the properties of SEW-CSPI composite gels, which can improve the potential utilization of SEW and SPI in food processing.     

Functional properties of ultrasonically generated flaxseed oil-dairy emulsions

This study reports on the functional properties of 7% flaxseed oil/milk emulsion obtained by sonication (OM) using 20 kHz ultrasound (US) at 176 W for 1–8 min in two different delivery formulae, viz., ready-to-drink (RTD) and lactic acid gel. The RTD emulsions showed no change in viscosity after sonication for up to 8 min followed by storage up to a minimum of 9 days at 4 ± 2 °C. Similarly, the oxidative stability of the RTD emulsion was studied by measuring the conjugated diene hydroperoxides (CD). The CD was unaffected after 8 min of ultrasonic processing. The safety aspect of US processing was evaluated by measuring the formation of CD at different power levels. The functional properties of OM gels were evaluated by small and large scale deformation studies. The sonication process improved the gelation characteristics, viz., decreased gelation time, increased elastic nature, decreased syneresis and increased gel strength. The presence of finer sono-emulsified oil globules, stabilized by partially denatured whey proteins, contributed to the improvements in the gel structure in comparison to sonicated and unsonicated pasteurized homogenized skim milk (PHSM) gels. A sono-emulsification process of 5 min followed by gelation for about 11 min can produce gels of highest textural attibutes.     

Emulsion gels stabilized by soybean protein isolate and pectin: Effects of high intensity ultrasound on the gel properties,stability and β-carotene digestive characteristics

In this study, soybean protein isolate (SPI) and pectin emulsion gels were prepared by thermal induction, and the effects of high intensity ultrasound (HIU) at various powers (0, 150, 300, 450 and 600 W) on the structure, gel properties and stability of emulsion gels were investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that the interaction between SPI and pectin was enhanced and the crystallinity of the emulsion gels was changed due to the HIU treatment. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) observations revealed that the particle size of the emulsion gels was decreased significantly by HIU treatment. The emulsion gel structure became more uniform and denser, which was conducive to storage stability. In addition, according to the low field nuclear magnetic resonance (LF-NMR) analysis, HIU treatment had no obvious impact on the content of bound water as the power increased to 450 W, while the content of free water decreased gradually and became immobilized water, which indicated that the water holding capacity of the emulsion gels was enhanced. Compared with untreated emulsion gel, differential scanning calorimetry (DSC) analysis showed that the denaturation temperature reached 131.9 ℃ from 128.2 ℃ when treated at 450 W. The chemical stability and bioaccessibility of β-carotene in the emulsion gels were improved significantly after HIU treatment during simulated in vitro digestion.     

Synergistic effects of oat β-glucan combined with ultrasound treatment on gel properties of silver carp surimi

The effect of oat β-glucan (OG) combined with ultrasound treatment on the gelation properties of silver carp surimi with different salt contents was investigated. The results demonstrated that the gelation properties of surimi gels at high salt concentration were superior than those at low salt level. The addition of OG or ultrasound treatment could significantly enhance the texture properties, gel strength and water holding capacity (WHC) of gel samples, regardless of salt contents. The ultrasound treatment improved the whiteness of surimi gels, whereas the OG addition slightly declined the whiteness. Both OG addition and ultrasound treatment markedly reduced the total sulfhydryl content (total SH) and strengthened the hydrophobic interactions, forming the more uniform and denser gel network structures, hence more water was captured in network structures and became immobilized. Moreover, the combined treatment of OG and ultrasound showed synergic action on the gelation properties of surimi, and the gel strength and WHC of low-salt surimi gel treated by the combination of OG and ultrasound were even superior than that of high-salt gel without OG by traditional heating.     

Effect of ultrasound pretreatment on structural,physicochemical, rheological and gelation properties of transglutaminase cross-linked whey protein soluble aggregates

A solution (10%, w/v) of whey protein soluble aggregates (WPISA) was pretreated with high-intensity ultrasound (HUS, 20 kHz) for different durations (10–40 min) before incubation with transglutaminase (TGase) to investigate the effect of HUS on the structural, physicochemical, rheological, and gelation properties of TGase cross-linked WPISA. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that HUS increased the amounts of high-molecular-weight polymers/aggregates in WPISA after incubation with TGase. HUS significantly increased (P < 0.05) the degree of TGase-mediated cross-linking in WPISA, as demonstrated by a reduction in free amino group contents. HUS significantly increased (P < 0.05) the particle size, intrinsic fluorescence intensity, and surface hydrophobicity of TGase cross-linked WPISA, but had no significant impact (P > 0.05) on the zeta-potential or total free sulfhydryl group content of TGase cross-linked WPISA. The apparent viscosity and the consistency index of TGase cross-linked WPISA were significantly increased by HUS (P < 0.05), which indicated that HUS facilitated the formation of more high-molecular-weight polymers. HUS significantly increased (P < 0.05) the water holding capacity and gel strength of glucono-δ-lactone (GDL)-induced TGase cross-linked WPISA gels. The results indicated that HUS could be an efficient tool for modifying WPISA to improve its degree of TGase-mediated cross-linking, which would lead to improved rheological and gelation properties.     

Solubilization and stable dispersion of myofibrillar proteins in water through the destruction and inhibition of the assembly of filaments using high-intensity ultrasound

The insolubility and poor dispersion of myofibrillar proteins (MPs) in water have always been the primary factors limiting the development of novel meat-based products. This study aimed to explore the mechanisms by which high-intensity ultrasound (HIU) at various power settings (0, 150, 300, 450 and 600 W) improved the solubility and dispersion stability of MPs in water. According to the solubility analysis, HIU significantly increased the water solubility of MPs (p < 0.05). The MPs treated with 450 W exhibited the best dispersion stability in water, which corresponded to the highest zeta-potential, smallest particle size and most uniform distribution (p < 0.05). Based on the circular dichroism and fluorescence spectroscopy and surface hydrophobicity analysis, the loss of the MP superhelix and subsequent random dissociation of the filamentous myosin structure appeared to be the main mechanism of MP solubilization. In addition, according to the zeta-potential, SDS-PAGE and Nano LC-ESI-MS/MS analyses, the increase in surface charge and the formation of soluble oligomers may provide additional forces to inhibit filament assembly, thereby improving the stability of the aqueous MP suspension. Atomic force microscopy (AFM) observations further confirmed these results. In conclusion, an HIU treatment effectively improves the solubility and dispersion stability of MP in water.     

Effects of ultrasonic–microwave combination treatment on the physicochemical,structure and gel properties of myofibrillar protein in Penaeus vannamei (Litopenaeus vannamei) surimi

The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic–microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic–microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic–microwave combination treatment was superior to that of either single treatment.     

High-intensity ultrasound improved the physicochemical and gelling properties of Litopenaeus vannamei myofibrillar protein

The effects of high-intensity ultrasound on the physicochemical and gelling properties of Litopenaeus vannamei (L. vannamei) myofibrillar protein (MP) were investigated. MP solutions were subjected to ultrasound treatment (power 100 W, 300 W, and 500 W). It was found that the carbonyl and free amino contents of MP increased significantly with increasing ultrasound power, accompanied by enhanced emulsification properties. The increase of free radical and carbonyl content indicated that ultrasound induced the oxidation of MP. With the increase of ultrasound power, it was found that the total sulfhydryl content of the shrimp MP decreased, but the surface hydrophobicity increased significantly, which might be closely related to the conformational changes of MP. Meanwhile, a significant increase of β-sheet but a decrease of α-helix in the secondary structure of MP was observed with increasing ultrasound power, indicating that ultrasound treatment induced the stretching and flexibility of MP molecules. SDS-PAGE showed that L. vannamei MP consisted of myosin heavy chain, actin, myosin light chain, paramyosin and tropomyosin. Ultrasound treatment could lead to some degree of oxidative aggregation of MP. The results of rheological properties indicated that ultrasound treatment enhanced the viscoelasticity of MP and further improved the gel strength of MP gel. This study can provide a theoretical basis for the functional modification of shrimp MP and the processing of its surimi products.     

Impact of combined ultrasound-microwave treatment on structural and functional properties of golden threadfin bream (Nemipterus virgatus) myofibrillar proteins and hydrolysates

The effects of microwave, ultrasound and combined ultrasound-microwave (UM) treatment with different intensities on structural and hydrolysis properties of myofibrillar protein (MP) were investigated. Free radical scavenging ability, angiotensin-I-converting enzyme (ACE) inhibitory activity, and cellular antioxidant and anti-inflammatory abilities of the related bioactive peptides were also evaluated. Raman spectroscopic analysis indicated that MP molecule tended to unfold and stretch with increasing in β-turn and random coil content under mild microwave (100 W), ultrasound (100–200 W) and combined UM treatments. Meanwhile, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed these treatments could also improve the thermal stability against heat-induced denaturation and degeneration. The 200 W ultrasound treatment clearly increased MP solubility by disrupting the highly-ordered aggregates into smaller filament and fragment structures. The 300 W ultrasound coupled with 100 W microwave treatment further enhanced these effects. The resulting partially denatured structure induced by suitable ultrasound and combined UM treatments increased the susceptibility of MP to exogenous enzymes, thereby accelerating hydrolytic process and yielding a high peptide concentration in MP hydrolysates. MP peptides could effectively inhibit free radical and ACE activity, which also improved the ability of antioxidant defence system, and suppressed the production of proinflammatory cytokines in RAW 264.7 cells stimulated by H₂O₂. The combination of 100 W microwave and 300 W ultrasound treatment was optimal method for generating bioactive MP peptides with the strongest multi-activity effects against H₂O₂-induced cell damage.     

Transglutaminase-induced gelation properties of soy protein isolate and wheat gluten mixtures with high intensity ultrasonic pretreatment

Soy protein isolate (SPI) and wheat gluten (WG) are widely used in commercial food applications in Asia for their nutritional value and functional properties. However, individually each exhibits poor gelation. In this study, we examined the microbial transglutaminase (MTGase)-induced gelation properties of SPI and WG mixtures with high intensity ultrasonic pretreatment. Ultrasonic treatment reduced the particle size of SPI/WG molecules, which led to improvements in surface hydrophobicity (H_o) and free sulfhydryl (SH) group content. However, MTGase crosslinking facilitated the formation of disulfide bonds, markedly decreasing the content of free SH groups. Ultrasonic treatment improved the gel strength, water holding capacity, and storage modulus and resulted in denser and more homogeneous networks of MTGase-induced SPI/WG gels. In addition, ultrasonic treatment changed the secondary structure of the gel samples as determined by Fourier transform infrared spectroscopic analysis, with a reduction in α-helices and β-turns and an increase in β-sheets and random coils. Thus, ultrasound is useful in facilitating the gelation properties of MTGase-induced SPI/WG gels and might expand their utilization in the food protein gelation industry.     

High-intensity ultrasound improves the physical stability of myofibrillar protein emulsion at low ionic strength by destroying and suppressing myosin molecular assembly

The specific molecular behavior of myofibrillar proteins (MPs) in low-salt media limits the development of muscle protein-based emulsions. This study aimed to evaluate the potential of high-intensity ultrasound (HIU; 150, 300, 450, and 600 W) to improve the physical stability of MP emulsion at low ionic strength and decipher the underlying mechanism. According to the physical stability analysis, HIU pretreatment, especially at 450 W power, significantly improved the physical stability of MP emulsions, as evidenced by the reduced particle size, enhanced inter-droplet interactions, and increased uniformity of the droplet size distribution (p < 0.05). The results of interfacial protein composition, Fourier transform infrared spectroscopy analysis, and microscopic morphology observation of the aqueous MP suspension suggested that HIU induced the depolymerization of filamentous myosin polymers and inhibited the subsequent self-assembly behavior. These effects may facilitate protein adsorption and molecular rearrangement at the oil–water interface, forming a complete interfacial layer and, thus, droplet stabilization. Confocal laser scanning microscopy observations further confirmed these results. In conclusion, these findings provide direct evidence for the role of HIU in improving the physical stability of MP emulsions at low ionic strength.     

Improved water solubility of myofibrillar proteins by ultrasound combined with glycation: A study of myosin molecular behavior

The poor water solubility of myofibrillar proteins (MPs) limits their application in food industry, and is directly related to the molecular behavior associated with myosin assembly into filaments. This study aims to explore the effect of high-intensity ultrasound (HIU) combined with nonenzymatic glycation on the solubility, structural characteristics, and filament-forming behavior of MPs in low ionic strength media. The results showed that the HIU (200–400 W) application could promote the subsequent glycation reaction between MPs and dextran (DX) and interfere with the electrostatic balance between myosin rods, suppressing the formation of filamentous myosin polymers. Glycated MPs pretreated by 400 W HIU had the highest solubility, which corresponded to the smallest particle size, highest zeta potential, and optimum storage stability (P < 0.05). Structure analysis and microscopic morphology observations suggested that the loss of the MP superhelix and the depolymerization of filamentous polymers were the main mechanisms for MP solubilization. In conclusion, HIU combined with glycation can effectively improve the water solubility of MPs by destroying or suppressing the assembly of myosin molecules.     

Diacylglycerol pre-emulsion prepared through ultrasound improves the gel properties of golden thread surimi

This study determined the influence of diacylglycerol (DAG) pre-emulsion on the gel properties and microstructure of golden thread surimi gels. DAG emulsion stabilized using sodium caseinate was pre-emulsified through ultrasound. The average particle size of DAG pre-emulsion decreased from 1324.15 nm to 41.19 nm, with notable improvements in apparent viscosity and storage stability. The surimi gels with different amounts (0%, 1%, 3%, 5%, and 7% w/w) of DAG pre-emulsion were prepared under heat induction. The whiteness of the composite gels markedly increased with the incorporation of DAG pre-emulsion. The peak T₂₂ value of immobilized water, the gel strength, and water-holding capacity increased gradually, but it slightly decreased with the addition of 7% pre-emulsion. The curve of G′ and G″ kept climbing as the concentration of pre-emulsion, and the microstructure of the gel network tended to become denser and more orderly. Principal component analysis (PCA) of electronic nose results showed that the surimi gels containing pre-emulsion could be clearly distinguished from the control group. In conclusion, the addition of 5% DAG pre-emulsion to surimi not only improved gel properties to the highest extent but also be compensated for lipid loss during the rinsing of surimi.     

Effect of high intensity ultrasound on gelation properties of silver carp surimi with different salt contents

Surimi from silver carp with different salt contents (0–5%) was obtained treated by high intensity ultrasound (HIU, 100 kHz 91 W·cm⁻²). The gelation properties of samples were evaluated by puncture properties, microstructures, water-holding capacity, dynamic rheological properties and intermolecular interactions. As the salt content increased from 0 to 5%, gel properties of surimi without HIU significantly improved. For samples with low-salt (0–2% NaCl) content, HIU induced obvious enhancement in breaking force and deformation. HIU promoted the protein aggregation linked by SS bonds, hydrophobic interactions and non-disulfide covalent bonds in surimi gels with low-salt content. Moreover, microstructures of HIU surimi gels with low-salt content were more compact than those of the corresponding control samples. HIU also improved the gelation properties of surimi with 3% NaCl to an extent. However, for high-salt (4–5% NaCl) samples, HIU decreased the breaking force and deformation of surimi gels due to the degradation of proteins suggested by increased TCA-soluble peptides. In conclusion, HIU effectively improved the gelation properties of surimi with low-salt content (0–2% NaCl), but was harmful for high-salt (4–5% NaCl) surimi. This might provide the theoretical basis for the production of low-salt surimi gels.     

Effect of ultrasound thawing,vacuum thawing,and microwave thawing on gelling properties of protein from porcine longissimus dorsi

Effect of new thawing methods (ultrasound thawing (UT), vacuum thawing, (VT), microwave thawing (MT)) on gelling properties of myofibrillar protein (MP) from porcine longissimus dorsi was investigated, compared with traditional thawing methods (water immersion thawing, (WT)) and fresh meat (FM). The results showed that a decrease in MP gelling properties of all thawing samples was observed. The increase in roughness of MP gel from all thawing samples explained that the flatter, smoother, and denser surface morphology of that from FM samples was destroyed based on the observation by atomic force microscopy. There was significant difference (P < 0.05) in all gel indicators (particle size, turbidity, whiteness, water-holding capacity (WHC), moisture distribution, rheological characteristics, surface morphology) of MP from MT samples and there was insignificant difference (P > 0.05) in turbidity, whiteness, WHC of MP from VT samples compared with that from FM samples. There was insignificant difference (P > 0.05) in gel properties between UT and VT. The effect of UT and VT (new thawing methods) on MP gelling properties was significantly lower (P < 0.05) than that of WT (traditional thawing methods), and the effect of that from MT was obviously compared with other thawing methods.     

Influence of high-intensity ultrasound on physicochemical and functional properties of a guamuchil Pithecellobium dulce (Roxb.) seed protein isolate

In this study, the influence of ultrasound on the physicochemical and functional properties of guamuchil seed protein isolate (GSPI) was investigated. The GSPI was prepared by alkaline extraction and isoelectric precipitation method followed by treating with ethanol (95%), from defatted guamuchil seed flour. GSPI suspensions (10%) were sonicated with a probe (20 kHz) at 3 power levels (200 W, 400 W, 600 W) for 15 and 30 min, in addition, to control treatment without ultrasound. Moisture content, water activity, bulk and compact densities and the L*, a* and b* color parameters of the GSPI decreased due to the ultrasound. Glutelin (61.1%) was the main protein fraction in GSPI. Results through Fourier transform infrared and fluorescence spectroscopy showed that ultrasound modified the secondary and tertiary protein structures of GSPI, which increased the surface hydrophobicity, molecular flexibility and in vitro digestibility of GSPI proteins by up to 114.8%, 57.3% and 12.5%, respectively. In addition, maximum reductions of 11.9% in particle size and 55.2% in turbidity of GSPI suspensions, as well as larger and more porous aggregates in GSPI lyophilized powders were observed by ultrasound impact. These structural and physicochemical changes had an improvement of up to 115.5% in solubility, 39.8% in oil absorption capacity, while the increases for emulsifying, foaming, gelling, flow and cohesion properties of GSPI were 87.4%, 74.2%, 40.0%, 44.4%, and 8.9%, respectively. The amelioration of the functional properties of GSPI by ultrasound could represent an alternative for its possible use as a food ingredient in industry.     

Effect of ultrasonic pretreatment on the rheology and structure of grass pea (Lathyrus sativus L.) protein emulsion gels induced by transglutaminase

In this study, emulsion gels were prepared by sonicated grass pea protein isolates (GPPI) at different ultrasonic amplitudes (25, 50 and 75 %) and times (5, 10 and 20 min). Formation of emulsion gels was induced by transglutaminase. Enzymatic gelation of emulsions stabilized by sonicated GPPI occurred in two stages. A relatively fast stage led to the formation of a weak gel which was followed by a slow stage that strongly reinforced the gel structure. Emulsion gels fabricated by sonicated GPPIs showed a homogeneous and uniform droplet distribution with higher elastic modulus compared to the native protein. A stiffer emulsion gel with a higher G' was formed after the protein was treated at 75 % amplitude for 10 min. After sonication of GPPI, the water holding capacity (WHC) of emulsion gels increased in accordance with the mechanical properties. Higher intermolecular cross-linking within the gel network increased the thermal stability of emulsion gels fabricated by sonicated GPPI. Although sonicated-GPPI emulsion gels clearly displayed homogenous microstructure in comparison to that made with native GPPI, the microstructures of these gels were nearly identical for all sonication amplitudes and times.