Gelation of single heated vs. double heated whey protein isolate

Gelation of single and double heated whey protein dispersions was investigated using Ca²⁺ as inducing agents. Whey protein isolate (WPI) dispersions (10% w/w) were single heated (30 min, 80 °C at pH 7.0) or double heated (30 min, 80 °C at pH 8.0 and 30 min, 80 °C at pH 7.0) and diluted to obtain the desired protein and/or calcium ions concentration (4–9% and 5–30 mm, respectively). Calcium ions were added directly or by using a dialysis method. Double-heated dispersions gelled faster at lower protein and calcium ion concentrations than single-heated dispersions. Gels obtained from double-heated dispersions had lower values of shear strain and shear stress at fracture than gels obtained from single-heated dispersions. Double heating caused a significant complex modulus (G*) increase at 4% WPI and 15 mm calcium ions in comparison with gels obtained from single-heated dispersion. Less significant differences between gels made from double and single-heated dispersions were observed at 6% WPI, however a higher value of complex modulus was obtained for 8% protein gels from the single-heated solution. Native and non-reduced SDS–PAGE did not show clearly the effect of different procedures of heating on the quantities of polymerised proteins. Proteins in double-heated dispersions had higher hydrophobicity. Increased calcium concentration caused decreased protein hydrophobicity for both single and double-heated solutions.     

Effect of radio frequency (RF) heating on the texture,colour and sensory properties of a comminuted pork meat product

Radio frequency (RF) cooking is a form of dielectric heating in which products are heated by subjecting them to an alternating electromagnetic field between two parallel electrodes. Although similar in some respects to Microwave heating, RF has been proposed to be more suitable for industrial heating of meats because of the greater penetration depths possible with this technology. In this study an RF cooking protocol was developed and its effect on selected quality attributes of pork based white pudding was examined. Whilst cooking of the product in air proved unfeasible due to arcing, use of a polyethylene cell with circulating hot water (80 °C) facilitated successful heating of the product. Application of RF using an optimised cooking protocol (RF power = 450 W, cell volume = 500 ml and continuous circulation) resulted in a mean end-point temperature of 73 °C after 7 min 40 s. Similar mean end-point temperatures in water bath and steam oven heated products were achieved after 29 and 33 min, respectively. A factorial experiment was conducted to assess selected quality attributes of the cooked puddings. Results show that RF heated puddings were not significantly different (P > 0.05) from water bath and steam oven heated products with regard to instrumental colour, instrumental texture (Kramer shear and texture profile analysis) and expressible fluid. Furthermore, results of a sensory similarity test involving 60 panellists indicated that panellists were not able to detect differences between puddings cooked by RF and conventional methods. Overall this suggests that RF heating technology could have potential in pasteurisation of meat products though further work is needed to verify this.     

Gelatin-based films containing hydrophobic plasticizers and saponin from Yucca schidigera as the surfactant

The aim of this study was to evaluate the incorporation of hydrophobic plasticizers (acetyltributyl citrate – ATB, tributyl citrate – TB and acetyltriethyl citrate – ATC) in a matrix of gelatin, using the saponin extracted from Yucca schidigera (yucca) as emulsifier, in the production of biodegradable emulsified films using the casting technique. High levels of hydrophobic plasticizers were incorporated, reaching up to 75% of plasticizer in relation to the protein (w/w) for ATB and TB, and up to 60% for ATC. The minimum values of water vapor permeability were 0.08, 0.07 and 0.06 g mm m^?2 h^?1 kPa^?1 for ATB, TB and ATC respectively, with no significant differences (p > 0.05). The water solubility of the films ranged from 21% to 59.5%. Although the WVP decreased, both scanning electron microscopy and laser scanning confocal microscopy indicated that the incorporation of the hydrophobic plasticizers did not occur homogeneously in the film matrix.     

Monitoring nisin desorption from a multi-layer polyethylene-based film coated with nisin loaded HPMC film and diffusion in agarose gel by an immunoassay (ELISA) method and a numerical modeling

Polyethylene-based films coated with nisin loaded HPMC films were put in contact with food simulants, i.e. agarose gels with 5 or 30% (w/w) fat. Nisin desorption from the multi-layer films and diffusion in agarose gels were monitored by ELISA (Enzyme Linked ImmunoSorbent Assay). The data obtained after 2 or 6 days of contact between antimicrobial films and agarose gels were employed to determine nisin mass transfer by numerical modeling following Fick's second law. The values were in the range from 0.87 × 10^? 3 m s^? 1 to 4.30 × 10^? 3 m s^? 1 and 6.5 × 10^? 11 m² s^? 1 to 3.3 × 10^? 10 m² s^? 1, for nisin apparent desorption and diffusion coefficients, respectively. The diffusion process was governed by interactions between food matrix simulant and nisin. Moreover, it was observed that the polymer in the coating did not modify plastic film initial mechanical resistance and water vapor permeability.Industrial relevanceThis paper concerns active packaging, considered as a new approach to preserve food shelf life. Active packaging is a real gain for plastic and Food industrials. The paper deals with coating as a manner to activate packaging. The impact of coating on film properties is investigated.Also, predictive models are proposed to determine antimicrobial agent desorption and diffusion during some storage conditions.     

Activation energy measurements in rheological analysis of cheese

Activation energy of flow (E_a) between 30 and 44 °C was calculated from temperature sweeps of cheeses with contrasting characteristics to determine its usefulness in predicting rheological behavior upon heating. Cheddar, Colby, whole milk Mozzarella, low-moisture part-skim Mozzarella, Parmesan, soft goat, and Queso Fresco cheeses were heated from 22 to 70 °C, and E_a was calculated from the resulting Arrhenius plots. Protein and moisture content were highly correlated with E_a. The E_a values for goat cheese and Queso Fresco, which did not flow when heated, were between 30 and 60 kJ mol^?1. Cheddar, Colby, and the Mozzarellas did flow upon heating, and their E_a values were between 100 and 150 kJ mol^?1. Parmesan, the hardest cheese, flowed rapidly with heat and had an E_a > 180 kJ mol^?1. E_a provides an objective means of quantitating the flow of cheese, and together with elastic modulus and viscous modulus provides a picture of the behavior of cheese as it is heated.     

Ohmic Heating Maximizes Gel Functionality of Pacific Whiting Surimi

Surimi without enzyme inhibitors containing 78% moisture and 2% NaCl was heated conventionally and ohmically to 90°C after holding at 55°C for 0, 1, 3 and 5 min. Gels heated slowly in a water bath exhibited poor gel quality, while the ohmically heated gels without holding at 55°C showed more than a twofold increase in shear stress and shear strain over conventionally heated gels. Degradation of myosin and actin was minimized by ohmic heating, resulting in a continuous network structure. Ohmic heating with a rapid heating rate was an effective method for maximizing gel functionality of Pacific whiting surimi without enzyme inhibitors.     

Pasteurization of fermented red pepper paste by ohmic heating

Ohmic heating was applied to a Korean traditional fermented food containing red pepper paste, called Gochujang with low thermal conductivity (0.458 W/m ∙ K), by varying frequencies (40–20,000 Hz) and applied voltages (20–60 V). Contrary to conduction heating, the entire sample was heated uniformly, and the specific heating rate was found to be highly dependent on the frequency, peaking at 5 kHz and 60 V. The results showed that complex differential equation and the Runge–Kutta fourth-order method are suitable for simulating the temperature profile during ohmic heating. The deactivation of vegetable cells of Bacillus strains on fermented red pepper paste by ohmic heating was indicated by a 99.7% reduction, compared with conduction heating for 8 min at 100 °C producing a 81.9% reduction. The organoleptic and physicochemical qualities of the samples pasteurized by ohmic heating were nearly the same as those of raw samples, and higher than those of conventionally heated samples.Industrial relevanceThe present study designed and implemented a novel sterilization process based on a static ohmic heating system with low-frequency AC at the laboratory scale for fermented red pepper paste with a low thermal conductivity (0.458 W/m ∙ K).The developed system was used to investigate the mechanisms and characteristics underlying the induction of ohmic heating and then, tested the pasteurization effect against microorganisms in fermented red pepper paste.Comparing with conventional heating processes, ohmic heating could provide rapid and uniform heating, thereby is more suitable for pasteurization and sterilization of viscous foods as fermented red pepper paste on industrial thermal processing.     

Kinetics of salmon quality changes during thermal processing

The kinetics of reactions leading to changes in salmon quality during thermal processing were evaluated. Small samples (D 30 mm × H 6 mm) cut from pink salmon (Oncorhynchus gorbuscha) fillets were sealed in aluminum containers (internal dimension: D 35 mm × H 6 mm) and heated in an oil bath at 100, 111.1, 121.1, and 131.1 °C for different time intervals up to 180, 150, 120, 90 min, respectively. A fractional conversion model was used to describe the increase in cook loss during heating; and a quadratic relationship to correlate cook loss with area shrinkage ratio. Color changes (CIE L¹, b¹ and ΔE) involved whitening and browning phases. In the browning phase, the changes of CIE L¹, b¹ and ΔE followed a zero-order reaction. The progressive change of texture with time as indicated by shear force during heating went through four different phases, and the second (rapid tenderizing) and third phases (slow toughening) were modeled using a first-order reaction kinetic model. The decay of thiamin during heating was modeled with two different relationships: a second-order reaction in which the temperature dependence of the rate constant followed an Arrhenius relationship; and a Weibull-log logistic model recently proposed.     

Gelation of whey protein and xanthan mixture: Effect of heating rate on rheological properties

The effects of heating rate and xanthan addition on the gelation of a 15% w/w whey protein solution at pH 7 and in 0.1 M phosphate buffer were studied using small-amplitude oscillatory shear (SAOS) rheological measurements and uniaxial compression tests. WPI solutions were heated from 25 to 90 °C at five heating rates (0.1, 1, 5, 10 and 20 °C/min). Gelation temperature of WPI decreased with decreasing of heating rates and with xanthan addition. Under uniaxial compression, the WPI gels prepared with no more than 0.2% w/w xanthan exhibited distinct fracture point and were tougher (i.e. higher fracture stress and fracture strain) than the gels prepared with no less than 0.5% w/w xanthan. In general, the fracture strain of WPI gels increased with heating rate, though not significantly, at all xanthan contents investigated. However, the fracture stress of WPI gels, generally, decreased with heating rate when xanthan content was 0–0.2% and increased with heating rate when xanthan content was 0.5 and 1%.     

Thermal inactivation of Bacillus anthracis Sterne in irradiated ground beef heated in a water bath or cooked on commercial grills

The thermal stability of heat-shocked and non-heat-shocked spores of the virulence-attenuated Sterne strain of Bacillus anthracis was evaluated at select temperatures in irradiated, raw ground beef (25% fat) heated in a water bath or cooked using two different commercial grills. For the former, 3-g portions of inoculated ground beef were packaged in bags that were completely immersed in a temperature-controlled circulating water bath held at 65 °C (149 °F), 70 °C (158 °F), 75°(167 °F), and 80 °C (176 °F) for a predetermined length of time. For the latter, formed ground beef patties (95-g each) were inoculated with spore stock A or B of the Sterne strain and then cooked on a commercial open-flame gas grill or on a commercial clamshell electric grill to achieve target internal temperatures of either 71.1 °C (160 °F), 82.2 °C (180 °F), or 93.3 °C (200 °F). Cooking ground beef patties on commercial grills, resulted in reductions of ca. 0.8 to 3.5 log₁₀ CFU/g for spore stocks A and B of B. anthracis Sterne after heating to 71.1 °C (160 °F), 82.2 °C (180 °F), or 93.3 °C (200 °F) on either the open-flame gas grill which required ca. 9.6 min to reach the target internal temperatures or on the clamshell electric grill which required ca. 4.0 min to reach the target internal temperatures. In comparison, our data using a water bath system and heating at 65° to 80 °C predict nearly 4 log reductions in spore levels for short times, ~½ min, depending possibly on the temperature. Thus, our data suggest that models based on heating ground beef in a water bath is not a good predictor of reductions of levels of spores of B. anthracis Sterne strain that would be obtained when cooking ground beef patties on commercial grills under conditions that may be typically used by consumers and/or retail establishments. Nevertheless, our data validated that cooking ground beef patties on a commercial grill at a temperature considered to be “well-done” and a temperature (71.1 °C;160 °F) recommended by the USDA/FSIS, is effective at killing spores of B. anthracis Sterne.Industrial relevanceHeating ground beef in a water bath or cooking ground beef patties on commercial grills under conditions simulating those that are used by consumers and/or that occur in retail food service establishments is effective at killing spores of B. anthracis Sterne.     

The dominating effect of ionic strength on the heat-induced denaturation and aggregation of β-lactoglobulin in simulated milk ultrafiltrate

The denaturation/aggregation behaviour of heated (78 °C, 10 min) β-lactoglobulin (1%, w/w) was examined as a function of heating pH (5.0–7.0), in the presence of different salts. Heating β-lactoglobulin in the presence of calcium (5 mm) significantly increased the level of aggregated protein at most heating pH values, compared to heating in water or sodium chloride (100 mm). Heating β-lactoglobulin in the presence of calcium (5 mm) and phosphate (5 mm), resulted in similar denaturation levels in the pH range 5.0–5.8 as in the presence of calcium (5 mm) alone but reduced denaturation in the pH range 6.0–7.0, probably due to the formation of insoluble calcium phosphate. The addition of NaCl (100 mm) counteracted the aggregation promoting properties of the calcium and calcium/phosphate systems. Heating β-lg in a simulated milk ultrafiltrate solution was similar to heating in NaCl alone. This suggested that Ca²⁺ effects alone may not explain the heat-induced denaturation/aggregation behaviour of β-lactoglobulin in milk whey systems.     

Structural and rheological properties of amaranth protein concentrate gels obtained by different processes

The heat-induced gelation of amaranth protein concentrates (APCs) by three processes was studied. The first was the conventional process for isolating protein (standard process-st), the second included an acid washing step prior to protein extraction (acid washing process-aw) and the third included heating (50 °C) during the alkaline extraction step (heat process-ht). The dispersions (12%, w/v) were heated to 55–90 °C and assessed by rheological measurements made under small deformations, whereas the gels obtained by heating at 70, 80 or 90 °C/30 min were subjected to uniaxial compression measurements (TPA and mechanical properties). The rheological parameters associated with the network structure, elasticity modulus (E) and storage modulus (G′), increased with increasing gelation temperature. For the APCst and APCht gels, protein aggregation occurred in two steps, whereas for APCaw, gelation occurred in a single step. The APCht gels showed the highest fracturability, hardness and adhesiveness, followed by the APCst and APCaw gels (p < 0.05). Similar results were obtained for the mechanical properties at fracture. Increasing the heat treatment temperature from 80 to 90 °C resulted in a more structured matrix with greater water-holding capacity as compared to gels obtained at 70 °C, and these properties were influenced by the extraction processes used to obtain the APCs. Heat extraction (APCht) improved the gelation and water-holding properties, whereas the acid treatment had the opposite effect.     

Water vapor transport properties during staling of bread crumb and crust as affected by heating rate

In order to develop a mathematical model to simulate mass transfer occurring between the crumb and the crust during bread staling, water vapor sorption properties, i.e., moisture diffusivity, WVP and sorption of bread crumb and crust were investigated at 15 °C. Two types of bread baked with two heating rates (7.39 °C/min and 6.32 °C/min) were considered. Sorption and desorption isotherms were determined using Dynamic Vapor Sorption (DVS) and FF and GAB models were applied in the range of 0–0.95 a_w, to fit isotherm curves. Diffusivity was determined from sorption isotherms by using Fick's law and WVP was measured by two methods (gravimetric and from sorption data). Results exhibited maximum values of D_eff in the range of 0.1 and 0.14 g/g d.b. moisture contents. They varied between 0.88 × 10^? 10 and 0.92 × 10^? 10 m²/s for the crust and between 2.24 × 10^? 10 and 2.64 × 10^? 10 m²/s for the crumb, baked respectively at 220 °C and 240 °C. Results of WVP showed that the crust baked at 240 °C was significantly more permeable than the crust baked at 220 °C. This fact was attributed to the difference in porosity and the molecular structure due to heating effects. Also, the presence of steam in the oven atmosphere enhanced the development of higher porosity in the crust, leading to different structures and properties. Moreover, SEM images showed that starch granules were intact and less swelled in the upper crust when baking at 240 °C, resulting in higher WVP.     

Rapid (microwave) heating rate effects on texture,fat/water holding,and microstructure of cooked comminuted meat batters

Comminuted and gelled, fat-containing meat products such as frankfurters and luncheon meats are commercially processed by heating relatively slowly (for up to 2 h or more) to an endpoint of about 70 °C prior to cooling. This study compared such a slow, ramp heating regime (0.5 °C/min), terminated at 70 °C, to rapid, square-wave cooking (one step: rapid 100 °C/min heating to 70 °C endpoint, plus isothermal holding prior to cooling, or two-step: rapid heating to 50 °C, holding, then rapid heating to 70 °C plus holding prior to cooling) on meat batter gel properties (fracture and small strain rheology, microstructure, cook loss, and expressible water). The results indicated that a rapid cooking process, with its inherent advantages of reduced process time, lower equipment footprint, and more efficient use of energy, can produce a product nearly equivalent in textural properties and cook yield to one processed by traditional smokehouse cooking when the cook value of the processes is similar and an intermediate (near 50 °C) holding step is included (two-step rapid heating). One-step rapid heating negatively affected gel structural homogeneity and water/fat holding properties of fat-containing gels.     

Effect of heating on the stability of grape and blueberry pomace procyanidins and total anthocyanins

Fruit by-products are rich sources of procyanidins and anthocyanins known for potential health benefits. Freeze dried blueberry pomace and grape pomace were heated in a forced air oven at 40, 60, 105, and 125 °C for 72, 48, 16, and 8 h respectively, to study the stability of procyanidins and total anthocyanins. Heating decreased procyanidin concentrations significantly (p < 0.05) in both blueberry and grape pomace, except when heated at 40 °C for 72 h. Reduction occurred when heated at 60 °C or above with no further reduction when heating temperature increased from 105 to 125 °C. Heating also affected total anthocyanin contents in both grape and blueberry pomace with no significant (p > 0.05) loss when heated at 40 °C. Total anthocyanin loss was highest at 125 °C for both blueberry (52%) and grape pomace (70%). Results suggested that while heating at lower temperatures for up to 3 days may not be detrimental, heating at higher temperatures for more than 8 h results in considerable loss of both the compounds.     

The potential of ohmic heating as an alternative to steam for heat processing shrimps

The potential application of Ohmic Heating as an alternative to the conventional steam cooking for shrimps is examined in this study. Defrosted unpeeled shrimps (Pandalus borealis) were cooked either in a steamer or ohmically up to a 72 °C core-temperature. The head, body and tail of steam-heated shrimps cooked at different rates whereas the OH treatment was more uniform and faster. The impact of shrimp size on heating rate was also evaluated, with an overall cooking time of 38 s and 59 s for steam-cooked small and large shrimps, respectively, while only 40 s where needed for OH regardless of shrimp size and measured anatomical location. No differences were found for cook loss and texture (WBSF and Kramer methods) between cooking methods. However, shrimp size seemed to determine the effect of OH on colour differences (ΔE), with greater differences observed in large vs. small shrimps, although overall ohmically-cooked shrimps showed less colour differences compared to those cooked conventionally with steam.Industrial relevanceTraditional heating processes such as boiling or steaming are used in industrial cooking of shrimps. However, the low rate of heat penetration to the thermal centre of shrimps leads to heterogeneous treatments resulting in overcooking which may reduce yield. Ohmic heating technology offers a potential alternative over conventional heat treatments as heat is generated volumetrically inside the food. This form of heat generation results in more uniform temperature distribution which leads to shorter processing times and potentially higher yields while still maintaining the colour and nutritional value of food. This paper hence exploits the potential of Ohmic heating technology as an alternative to conventional steam processing for the cooking of shrimps.     

Moisture diffusivity and shrinkage of broad beans during bulk drying in an inert medium fluidized bed dryer assisted by dielectric heating

Drying behavior of broad beans (Vicia faba) was studied in a pilot scaled fluidized bed dryer with inert particles assisted by dielectric heating. The effective diffusion coefficient of moisture transfer was determined by Fickian method at four different air drying temperatures of 35, 45, 55 and 65 °C. Correlations for moisture diffusivity as a function of moisture content and temperature of the drying medium were developed. The values of moisture diffusivity were obtained within the range of 1.27 × 10^?9–6.48 × 10^?9 m²/s and the activation energies for FBD and FBD + DE were found to be 27.71 and 17.10 kJ/mol, respectively. The shrinkage behavior of the broad beans was also investigated by considering the volume ratio of (V/V_O) to be function of moisture content alone and fitting a polynomial of the third order. The dielectric heating power was also found to be effective on the rate of drying.     

Effect of ohmic heating on texture,microbial load,and cadmium and lead content of Chilean blue mussel (Mytilus chilensis)

The effect of ohmic heating (OH) on the texture, microbial load, and cadmium (Cd) and lead (Pb) content was evaluated in Chilean blue mussel (Mytilus chilensis) at shucking and subsequent canning. Mussel samples were processed by OH and blanching (BLAN) at 50 ± 1 °C, 70 ± 1 °C and 90 ± 1 °C for shucking and then canning at 115 °C for 20 min. The Cd and Pb content in fresh mussels was 2.47 ± 0.18 μg g^− 1 and 5.26 ± 0.55 μg g^− 1 dry weight (dw). The greatest reduction in Cd content was reached at 90 ± 1 °C by OH with 1.67 ± 0.06 μg g^− 1 (dw) and 1.69 ± 0.08 μg g^− 1 (dw) by BLAN. At the same temperature, the Pb content was reduced to 4.18 ± 0.24 μg g^− 1 dw for OH and 4.14 ± 0.30 μg g^− 1 dw for BLAN. The cutting strength of fresh samples (21.35 ± 2.44 N) significantly decreased in samples processed by OH (15.65 ± 1.36 N) at 90 ± 1 °C compared with BLAN samples (20.41 ± 3.16 N) at the same temperature. The initial mean count for mesophilic aerobic microorganisms and Enterobacteriaceae was 3.8 log cfu/g and 2.5 log cfu/g, respectively. The mesophilic aerobic microorganism count was reduced by 1.7 logarithmical units, while Enterobacteriaceae counts were reduced to undetectable levels by OH at 90 ± 1 °C.Industrial relevanceHigh temperature short time (HTST) processes rely on rapid convection heat transfer and are thus well suited to liquid foods. But, they are, however, limited in application to particulates since, for particles more than a couple of millimeters thick, the processing time is insufficient for heat to transfer to the center to give sterility. Ohmic heating is an emerging technology and very promising in food industries. It is a thermal process in which heat is generated internally in food and acts as a resistance to the flow of alternating electric current. This type of treatment prevents overheating by producing less deterioration in food components. It is a rapid procedure that allows food to conserve its natural properties; microorganisms and enzymes are also inactivated. The purpose of the present work was to evaluate the effect of Ohmic heating on mechanical properties, microbial load, Cd and Pb content in the opening and subsequent canning of Chilean blue mussel (Mytilus chilensis). This information could be used for the seafood industries in order to improve thermal heating processes in mussels.     

Effect of polysaccharides with different ionic charge on the rheological,microstructural and textural properties of acid milk gels

The effects of addition of polysaccharides with different ionic charge on rheology, microstructure, texture and water holding capacity (WHC) of acid milk gels were studied and compared to that of gelatin addition. Similar to gelatin, starch (neutral) and xanthan gum (anionic) did not prevent milk gelation in the first 30 min of the acidification stage, even at high concentrations, and the typical casein network in acid milk gels could still be seen from electron micrographs; gelling and melting of these hydrocolloids were observed during the cooling and heating stages at specific concentrations. On the other hand, two neutral polysaccharides, guar gum (≥ 0.05%) and locust bean gum [LBG] (≥ 0.1%) inhibited milk gelation from the beginning of the acidification stage; the microstructure of the gel was modified greatly and no gelling/melting was observed during the cooling or heating stages. Another anionic polysaccharide, carrageenan, induced earlier milk gelation at low concentration (≤ 0.05%), but inhibited gelation entirely at high concentration (0.2%); inflections at ~ 27 °C and 21 °C were also observed during the cooling and heating stages at 0.05% concentration. The gel microstructure was not changed greatly, but showed smaller particle size at a carrageenan concentration of 0.05% than control sample. None of the polysaccharides showed as much improvement in WHC of the milk gels as gelatin did. Hence, xanthan and starch were found to be closer to gelatin in their effect on acid milk gels compared to guar gum, LBG and carrageenan.     

Effect of soy protein substitution for sodium caseinate on the transglutaminate-induced cold and thermal gelation of myofibrillar protein

The influence of soy protein isolate (SPI) substitution for sodium caseinate (SC) on the properties of cold-set (4 °C) and heat-induced gels of pork myofibrillar protein (MP) incubated with microbial transglutaminase (TG) was investigated. The strength of cold-set MP–SC gels (formed in 0.45 M, NaCl, 50 mM phosphate buffer, pH 6.25) increased with time of TG incubation, but those gels with more than 66% SPI substituted for SC had a >26% reduced strength (P < 0.05). Upon cooking, both incubated and non-incubated protein sols were quickly transformed into highly elastic gels, showing up to 6000 Pa in storage modulus (G′) at the final temperature (72 °C). However, no differences (P < 0.05) in G′ were observed between heated samples with SPI and SC. Myosin heavy chain, casein and soy proteins gradually disappeared with TG incubation, contributing to MP gel network formation. Both cold-set and heat-induced gels had a compact protein matrix, attributable to protein cross-linking by TG.