Addition Of Microbial Transglutaminase Research Articles

Mechanically Enhanced Salmo salar Gelatin by Enzymatic Cross-linking: Premise of a Bioinspired Material for Food Packaging, Cosmetics, and Biomedical Applications.

Marine animal by-products of the food industry are a great source of valuable biomolecules. Skins and bones are rich in collagen, a protein with various applications in food, cosmetic, healthcare, and medical industries in its native form or partially hydrolyzed (gelatin). Salmon gelatin is a candidate of interest due to its high biomass production available through salmon consumption, its biodegradability, and its high biocompatibility. However, its low mechanical and thermal properties can be an obstacle for various applications requiring cohesive material. Thus, gelatin modification by cross-linking is necessary. Enzymatic cross-linking by microbial transglutaminase (MTG) is preferred to chemical cross-linking to avoid the formation of potentially cytotoxic residues. In this work, the potential of salmon skin gelatin was investigated, in a comparative study with porcine gelatin, and an enzymatic versus chemical cross-linking analysis. For this purpose, the two cross-linking methods were applied to produce three-dimensional, porous, and mechanically reinforced hydrogels and sponges with different MTG ratios (2%, 5%, and 10% w/w gelatin). Their biochemical, rheological, and structural properties were characterized, as well as the stability of the material, including the degree of syneresis and the water-binding capacity. The results showed that gelatin enzymatically cross-linked produced material with high cross-linking densities over 70% of free amines. The MTG addition seemed to play a crucial role, as shown by the increase in mechanical and thermal resistances with the production of a cohesive material stable above 40°C for at least 7days and comparable to porcine and chemically cross-linked gelatins. Two prototypes were obtained with similar thermal resistances but different microstructures and viscoelastic properties, due to different formation dynamics of the covalent network. Considering these results, the enzymatically cross-linked salmon gelatin is a relevant candidate as a biopolymer for the production of matrix for a wide range of biotechnological applications such as food packaging, cosmetic patch, wound healing dressing, or tissue substitute.

Utilization of Reconstituted Whey Powder and Microbial Transglutaminase in Ayran (Drinking Yogurt) Production.

SUMMARYResearch backgroundIn industrial ayran production, milk is diluted to the desired protein content (2% (m/V)) prior to fermentation by yogurt starter cultures by partial replacement of cheese whey in reconstituted form with potable water. This may be an alternative way of protein recovery from cheese by-products as well as reducing the production costs since less milk is used in ayran production. On the other hand, the balance between milk caseins and whey proteins is disturbed when cheese whey is added to milk for ayran production, which likely leads to a time-dependent phase separation during cold storage. Modification of ayran matrix by enzymatic crosslinking of proteins may be a solution to overcome this potential physical instability of ayran. This topic has not been explored to date, and the present study was designed to investigate the possibilities of utilization of reconstituted whey powder (RWP) and microbial transglutaminase (MTG) in ayran production.Experimental approachMilk was diluted to obtain 2% protein level using RWP and potable water. The aim of utilization of RWP was to meet 5, 10 or 15% of the protein content of the final product. RWP solutions were obtained by calculating the amounts of whey powder required to meet the specified ratios and mixing it with the water required for dilution. We prepared eight different ayran samples divided in three groups, namely group A: prepared by partially diluting milk with RWP to obtain 5, 10 or 15% of total protein amount in the product, group AMTG: prepared by adding microbial transglutaminase (0.5 U per g of protein) to group A samples, and control group without RWP and with or without the addition of MTG. The gross composition, physical (phase separation and viscosity, chemical (volatile and peptide profiles and SDS-PAGE electrophoresis patterns) and sensory properties of the samples were evaluated throughout 15 days of storage with weekly intervals.Results and conclusionsSince the amounts of whey powder used to obtain RWP were different, dry matter levels of the samples differed. Using RWP in ayran production increased the phase separation slightly. Incorporation of MTG affected the physical properties of the ayran samples positively and prevented phase separation at a satisfactory level. SDS-PAGE electrophoretograms revealed that cross-linking between proteins triggered by MTG formed intense bonds at high molecular mass regions. The remaining parameters were not affected by MTG. Results revealed that the samples with 10% RWP with and without addition of MTG were determined as the formulations with the highest commercialization potential.Novelty and scientific contributionUtilizing RWP in the production of ayran to reduce the protein content of the final product to the desired level is a new approach. Since complete replacement of RWP with potable water to dilute milk to reach 2% (m/V) protein likely leads to lower sensory scores, we have investigated a possibility of partial replacement of RWP with potable water. A time-dependent phase separation is the major challenge of industrial ayran production. This physical problem was largely eliminated by means of MTG-mediated cross-linking of milk proteins. The proposed novel ayran production method offers dairy industry reduction of production costs and contributes to sustainability in milk production since smaller volume of milk is used to reach desired protein content in the final product.

Effects of transglutaminase enzyme on physicochemical properties of milkfish (Chanos chanos) surimi gel

Milkfish is one type of fish that can be used as raw material for surimi. However, previous research indicated that the quality of surimi powder produced from milkfish needed some improvements in order to produce surimi with good texture and strength gel. The addition of microbial transglutaminase (MTGase) enzyme is expected to produce surimi with better gel characteristics. The research objectives were to determine the best enzyme concentration and reaction time in the formation of surimi gel and to determine the effect of enzyme addition on the physical and chemical characteristics of surimi gel produced. The research was divided into two stages: 1) preparation for making surimi, and 2) determination of enzyme concentration and reaction time for surimi gel formation. The research treatment consisted of two factors, which were enzyme concentration (0, 0.1, 0.3, 0.5 units/g of surimi) and reaction time (0, 30, 60 mins). The observation parameters consisted of yield, gel strength, whiteness, pH, water content, protein content, and fat content. The results showed that the best concentration of MTGase enzyme was 0.5 units/ g with a reaction time of 60 mins. The addition of transglutaminase enzyme gave an effect significantly on gel strength, whiteness, protein content, and fat content in the milkfish surimi gel produced.

Effect of microbial lipase and transglutaminase on the textural, physicochemical, and microbial parameters of fresh quark cheese

In this study, the addition of microbial transglutaminase (MTG) and lipase in quark cheese samples was studied during storage (21 d). Four types of cheese were made using 3 different levels of MTG (T1, 0.1 g/L; T2, 0.2 g/L; T3, 0.3 g/L) and lipase (T1, 0.02 g/L; T2, 0.04 g/L; T3, 0.06 g/L), and one cheese was made without any treatment as a control sample. The physicochemical, textural, microbial, and sensory properties of cheese samples were monitored at 1, 7, 14, and 21 d of storage period. The results showed that the treated samples had higher proteolysis and lipolysis activities during storage than the control sample. The textural analysis indicated an insignificant increase in the hardness value of the enzyme-treated sample. Also, the sensory analysis exhibited that the treated samples had higher texture acceptability. The higher concentration of enzymes resulted in lower color, odor, taste, and overall acceptability, and higher microbial population. Finally, the addition of microbial MTG and lipase in preparation of quark cheese samples could be recommended for a short storage time.

Characterization of edible films from whey proteins treated with heat, ultrasounds and/or transglutaminase. Application in cheese slices packaging

Abstract Application of high power ultrasound and microbial transglutaminase addition, and their combination, have been studied for the modification of protein structure and crosslinking in order to change the properties of whey protein concentrate edible films. They were compared to untreated and heat-treated films (from heat-treated solutions). Ultrasound treatment modified some film properties. Water vapor permeability of ultrasound-treated films was slightly lower than those of untreated and heat-treated films. Ultrasound treatment increased tensile and puncture strengths of films in comparison with untreated samples. Transglutaminase addition only increased puncture deformation values and made films less green, more yellow and darker than non-added films. Heat-treated films showed better mechanical properties and were selected for a preliminary evaluation as separation material of cheese slices; they exhibited similar results regarding slice separation easiness and slice wholeness after separation that the commercial material, without modifying cheese color and odor.

In vitro pepsin digestion of silver carp (Hypophthalmichthys molitrix) surimi gels after cross-linking by Microbial Transglutaminase (MTGase)

The addition of microbial transglutaminase (MTGase) in surimi gel protein promote cross-linking and improvement of textural properties. In this study, the effects of cross-linking by MTGase on digestibility by pepsin were investigated using different methods, including, scanning electron microscopy (SEM), particle size, dry matter digestibility, Tricine SDS-PAGE, LC-MS/MS, and analysis of amino acids. Gel properties and cross-linking of surimi gels increased significantly (P < 0.05) when surimi was induced by MTGase. Gels with MTGase prohibited the hydrolysis at the beginning because enhanced cross-linking reduced the accessibility of pepsin to the hydrolytic site and the hydrolysis rate increased more rapidly once the network was destroyed during the first 30 min of digestion. The amounts of peptides and amino acids reached their maximum at the end of digestion and showed slight difference to the control gels. The digestion sites and the quantities of peptides from myosin heavy chain also differed between two kinds of surimi gels. This research can help explore the impact of structure on surimi foods, which will improve elastic texture, nutritional value, and provide a delayed reaction in digestion that potentially enhances the feeling of satiety; this delay could control caloric intake without affecting food value.

Gelling properties of vacuum-freeze dried surimi powder as influenced by heating method and microbial transglutaminase

Effects of heating method and addition of microbial transglutaminase (MTGase) on properties of gels made from vacuum-freeze dried silver carp surimi were investigated. After vacuum-freeze drying, surface hydrophobicity of surimi proteins obviously increased, Ca2+-ATPase activity slightly decreased, while α-helix percentage significantly decreased, indicating the surimi proteins were partially denaturated. Consequently, the dried surimi formed gels (D gel) with significantly lower breaking force, penetration distance and water holding capacity as compared with those of gels made from frozen surimi (F gel) under all the heating methods. With addition of MTGase, breaking force of the D gels heated at 40 °C/60 min and 90 °C/30 min was not significantly different from those of F gels, while was slightly lower under the heating of 40 °C/60 min + 90 °C/30 min. After adding MTGase, water holding capacity of the D gel under 90 °C heating increased significantly, while the gels under the other heating methods slightly deceased. Heating method obviously influenced color parameters of D gels while MTGase addition did not. Setting (40 °C) and MTGase addition induced covalent cross-linking of myosin heavy chains of D gels. MTGase addition reduced the uniformity of the water distribution in D gels.

Quality Assessment of Wheat Bread with Microbial Transglutaminase Supplemented with Hull-Less Barley Flour

Background: In the current study, the impact of MTG incorporation (0, 0.5%, 1%, 1.5% and 2%; W/W) into wheat flour supplemented with 20, 35 and 50% of hull-less barley flour on quality parameters of produced bread were investigated. Soy Protein Isolate (SPI) was used at a level of 3% (w/w) in order to increase the level of lysyl residues as well as extend the crosslinking of protein matrix. Material and Methods: Prepared bread was evaluated in terms of loaf volume, color characteristics and firmness during baking. Results: The addition of MTG on wheat proteins significantly decreased the loaf volume and extensibility of samples while the resistance and lightness of samples were increased. Incorporation of MTG at 0.5% would decrease the degree of softening and mixing tolerance index of flours. Conclusion: The formulation of hull-less barley bread quality could be improved by incorporation of MTG. Keywords: Microbial Transglutaminase (MTG), bread, hull-less barley, quality, Soy Protein Isolate (SPI), wheat.

Effect of Microbial Transglutaminase on Protein Electrophoretic Pattern and Solubility of Wheat Flour and Hull-Less Barley Flour Blends

Background: Barley flour does not contain gluten, so preparation of high-quality bread is not easy. Thus, the incorporation of microbial transglutaminase (MTG) can be attributed as one of the possible strategies to provide crosslinks between wheat and barley proteins to prepare a similar structure to the desired network of gluten. Methods: The MTG, at different levels (0.5, 1, 1.5, and 2%) was added to wheat and hull-less barley in order to evaluate the solubility of available proteins and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) patterns of (20, 35, 50%) dough proteins as well as their fractions by using an electrophoretic system. Also, to enhance the extent of cross-linking in protein matrix by incorporation of MTG, soy protein isolate (SPI) was used (1% MTG+3% SPI, 1.5% MTG+3% SPI). Results: Interactions between wheat and hull-less barley proteins were intensified due to the formation of catalyzed intermolecular covalent bonds by transglutaminase. According to SDS-PAGE results with increment in the levels of MTG, a progressive decrease in the intensity of the bands corresponding to the molecular weight of around 66 KDa was observed. Also by the addition of MTG, the amounts of the soluble proteins (albumin and glubolin) were significantly decreased and the concentrations of insoluble proteins (glutenin and gliadins) were increased. Conclusion: The addition of hull-less barley flour to wheat flour not only provides protein-enriched dough with better amino acid balance but also has influences on dough properties. Keywords: Transglutaminase, electrophoresis, solubility, hull-less barley, wheat flour.

Preparation of soy protein-based microgel particles using a hydrogel homogenizing strategy and their interfacial properties

In this work, a two-step strategy for fabricating soy protein-based microgel particles was introduced. Gel preparation and homogenization made up the two steps. Microgel particles with nano-scale size were obtained by homogenizing the hydrogel made from soy protein isolate (SPI) with the addition of microbial transglutaminase (MTGase). Colloidal stability, surface hydrophobicity and interfacial properties of the microgel particles were systematically investigated. We confirmed that the microgels had a more rigid conformation when compared to that of SPI, which was attributed to the covalent cross-links inside the microgels formed during gel preparation. By comparison with SPI, the microgel particles with three-phase contact angles more close to 90° exhibited lower surface activity, weaker intermolecular interactions at the interface. We found that most of the microgels adsorbed at the interface and stabilize Pickering type oil-in-water (O/W) emulsion at the pH around the isoelectric point of SPI. The resulting emulsion had good storage stability for 8 weeks. This preparation method, which requires simple operation and common devices, provides a new perspective of fabricating edible functional particulates for food industry.

Optimum processing conditions for slowly heated surimi seafood using protease-laden Pacific whiting surimi

Pacific whiting surimi was examined to develop optimum conditions for slowly heated surimi seafood like fish balls. Breaking force and penetration distance increased significantly (p < 0.05) with the addition of egg white (EW), calcium lactate and microbial transglutaminase (MTG). Setting effects on textural properties were significantly (p < 0.05) affected by MTG addition. Even without MTG addition, breaking force and penetration distance also increased significantly (p < 0.05) when setting time was extended up to 6 h, possibly resulting from the role of endogenous transglutaminase (ETG). The addition of MTG resulted in a hard, but less deformable gel when setting time exceeded 2 h. Enzyme autolysis showed the addition of EW at 1 g/100 g paste effectively inhibited endogenous proteases. Results suggested Pacific whiting surimi, which is hardly used for slowly heated surimi seafood due to the textural degradation by proteases, can be successfully used to produce high quality fish balls when combined with 3 g/100 g EW, 0.2 g/100 g calcium lactate and setting at 25 °C for 2–6 h with MTG or 4–6 h without MTG.

Nonprotein Nitrogenous Compounds and Gelling Property of Whitecheek Shark (C archarhinus Dussumieri ) Mince as Affected by Washing and Microbial Transglutaminase

Changes in nonprotein nitrogenous compounds and gelling properties of whitecheek shark (Carcharhinus dussumieri) meat during iced storage for 12 days were monitored. Total volatile base (TVB), trimethylamine (TMA) and ammonia contents increased, whereas urea content decreased during the storage (P < 0.05). TVB, TMA, urea and ammonia contents were lower in washed mince, indicating the removal of those compounds by washing. The addition of microbial transglutaminase (MTGase, 0.6 unit/g sample) was able to increase breaking force, deformation and water-holding capacity of both gels from mince and washed mince. Nevertheless, gel strengthening effect of MTGase was lowered when mince or washed mince were obtained from shark stored for an extended time. Polymerization of myosin heavy chain was enhanced when MTGase was incorporated but took place at a lower degree for mince and washed mince produced from unfresh shark. Washing process in combination with MTGase addition could therefore improve gel quality of shark meat. Practical Applications Shark meat is a good source of protein, which could be a suitable source for surimi production. However, the meat is considered to have a low market value because of undesirable odor, which is mainly from the decomposition of urea to ammonia during extended storage. Appropriate washing to remove those compounds, along with the use of microbial transglutaminase (MTGase), can be a promising means to improve the textural properties of gels from shark mince. Thus, shark meat can be better exploited, especially for the surimi industry.

Analysis of the effect of heating on rheological attributes of washed mechanically recovered chicken meat modified with transglutaminase

The study was conducted on mechanically recovered poultry meat subjected to washing and separation of fat and connective tissue in order to produce a myofibril protein isolate. The myofibril preparation (MP) was modified by microbial transglutaminase (MTG). For this purpose MP was supplemented with 3g/kg MTG and modified at a temperature of 6–7°C for 5h. The character of changes in the mechanical properties of modified MP, occurring during heating and cooling within the temperature range of 20–80–20°C, was analysed. Stiffness modulus (G1), loss factor (tgδ) and dynamic viscosity (η) were determined by dynamic mechanical thermal analysis. Enzymatic modification of MP and heating caused significant changes in the structure of the tested protein systems. Heating of MP samples made it possible to identify two areas of change in G1 values (up to 45°C and >50°C). Samples with an addition of MTG were characterised by higher values of the modulus in comparison to the control system. The cross-linking action of the enzyme resulted in a variation of G1 and tgδ values between the tested systems.

The addition of buttermilk powder and transglutaminase improves textural and organoleptic properties of fat-free buffalo yogurt

To meet the increased consumer demand for yogurt with reduced fat content, various efforts have been made to improve the quality of reduced-fat variants that still is regarded as having inferior quality. As an alternative, a yogurt was produced from buffalo skim milk with the addition of microbial transglutaminase (TG; 1 U.g−1 protein) and buttermilk powder (BMP; 1 and 2% “w/w”). For comparison, a fat-free variant without TG or BMP and a full-fat yogurt were studied. Monitoring the pH drop during incubation time revealed that TG did not interfere with the pH reduction, while BMP addition accelerated the decline in pH. TG treatment or BMP addition substantially improved the water holding capacity functionality of the yogurt gel. Electrophoretic analysis revealed that the addition of BMP enhanced the reactivity of TG as indicated by the appearance of high molecular weight protein polymer bands. These results were confirmed by scanning electron microscope analysis. The addition of TG and BMP, either individually or in combination, showed a marked impact on gel network, resulting in a more compact and dense gel structure accompanied by irregular agglomerated clusters of protein aggregates. Fat-free yogurts of individually BMP addition exhibited the most desirable organoleptic attributes as indicated by a sensory panel and were perceived as similar to the full-fat yogurt perception. Overall, the addition of TG or BMP appeared to have potential as a valuable alternative in fat-free yogurt production, and BMP can be used as a source of extra protein, which in turn offers promising option to develop innovative functional fat-free yogurt.

Effect of seasonal changes on the gelling properties of farmed sea bass (Dicentrarchus labrax)

The effect of seasonal changes (summer versus winter) upon the quality of heat-induced gel products from farmed sea bass (Dicentrarchus labrax) was studied. Moreover, the effect of microbial transglutaminase addition (0.5%, w/w) on the quality was assessed. Fat content of gel products attained from sea bass grown during summer was higher (12.0% versus 7.6%). Textural properties of the gels from the summer fish were higher. Protein of gels from winter fish was less soluble in SDS + DTT (sodium dodecyl sulphate, SDS; dithiothreitol, DTT). Contrary to some literature, higher fat level may have played a protective role during processing. Accordingly, season via fat content variation had a strong effect on the gelling ability of heat-induced gels prepared from sea bass.

Effects of dietary fibre and microbial transglutaminase addition on the rheological and textural properties of protein gels from different fish species

The effect of microbial transglutaminase (MTGase) and dietary fibre (DF) from pea and chicory on the dynamic rheological properties of protein paste were studied for hake, gilthead seabream, sea bass, and meagre.Meagre and gilthead seabream presented higher storage modulus (G′) and higher transition temperatures marking the various phases of thermal gelling. The incorporation of chicory DF in the formulations reduced G′. It was found that high degree of protein denaturation enhanced gel hardness. On the other hand, low degree of protein denaturation produced gels with high deformability. In accordance to this, the gels of those species with lower protein unfolding at a given temperature benefited most from MTGase addition.

Development of soy‐based cream cheese via the addition of microbial transglutaminase, soy protein isolate and maltodextrin

PurposeThe aim of this study is to develop a soy‐based cream cheese (SCC) with textural characteristics comparable to that of commercial dairy cream cheese (DCC) via the addition of microbial transglutaminase (MTG), soy protein isolate (SPI) and maltodextrin (MD).Design/methodology/approachResponse surface methodology (RSM) was employed in this study to determine the effects of MTG, MD and SPI on firmness of SCC.FindingsThe second‐order model generated via RSM was significant with only a 9.76 per cent variation not explained by the model. The coefficient of regression revealed that MTG, MD and SPI showed significant linear effects (P&lt;0.0001) on the firmness of SCC, while MTG and SPI showed significant quadratic effects. The model successfully predicted and developed a SCC model with similar firmness as that of DCC; via the combination of 2.57 per cent (w/w) of MTG, 19.69 per cent (w/w) of SPI and 19.69 per cent (w/w) of MD. Physicochemical analyses revealed that SCC possessed lower fat content, reduced saturated fatty acid and zero trans fat. Further rheological measurements revealed that SCC was more solid‐like at room temperature, but less elastic at refrigerated temperature compared to DCC. SEM and SDS‐PAGE analyses affirmed that the textural changes of SCC were attributed to MTG‐induced cross‐linking.Originality/valueThe research demonstrated that a non‐dairy cream cheese could be developed using soy. In addition, the SCC also contained better nutritional properties compared to its dairy counterpart.

Effect of Microbial Transglutaminase on Gel Properties and Film Characteristics of Gelatin from Lizardfish (Saurida spp.) Scales

The addition of microbial transglutaminase (MTGase) generally increased the gel strength of lizardfish (Saurida spp.) scale gelatin gels (P≤0.05) with an increase in gel strength with the addition of MTGase up to 0.5% (w/v). The texture profile analysis compression tests of lizardfish scale gelatin gel with and without MTGase were studied to determine their effects on gel characteristics. MTGase added to the gels decreased the band intensity of the β- and α-components with increasing concentrations of enzyme. Gel microstructures with various concentration of MTGase showed denser strands in the gels with enzyme compared with the looser stands in non-enzyme-treated gel samples. Films cast from lizardfish scale gelatin with and without 0.5% MTGase and bovine gelatin films were transparent and flexible. The lizardfish gelatin films were all slightly yellowish while the bovine gelatin films were clearer. The L value of bovine gelatin films had the highest value (P≤0.05) whereas lizardfish scale gelatin films with and without enzyme were not significantly different (P>0.05) for L, a, and b values and ΔE. The film's mechanical properties included tensile strength (TS) and elongation at break (E) were not significantly different (P > 0.05) for E and the films of lizardfish scale gelatin showed higher TS than the films without enzyme added (P ≤ 0.05). The water vapor permeability of films from lizardfish scale gelatin with and without 0.5% MTGase and bovine gelatin films were 21.0 ± 0.17, 26.3 ± 0.79, and 25.8 ± 0.09 g·mm/m(2)·d·kPa, respectively, while the oxygen transmission rate of all 3 types of films were less than 50 cc O(2)/m(2)·d.

Improvement of Cold and Thermally Induced Gelation of Giant Squid (Dosidicus gigas) Surimi

Depending on the season of capture, giant squid (Dosidicus gigas) surimi processed by isoelectric precipitation presents low gel strength. Addition of microbial transglutaminase (MTGase) and application of high isostatic pressure (300 MPa) to improve physicochemical properties were assayed for purposes of making “suwari” gels and heated gels for use in restructured products which have a raw or cooked appearance. The physicochemical properties of both pressurized and unpressurized gels induced by application of 30°C/1 h improved when MTGase was added. In contrast, addition of MTGase was less effective in gels subsequently heated at 90°C/30 min after 30°C/1 h. High pressure treatment for 30 min at 300 MPa and 15°C helped to produce gels with better mechanical and water binding properties, whether treated for 30°C/1 h only or for 30°C/1 h plus 30-min heat treatment at 90°C. High pressure treatment also reduced lightness.

Study of two different cold restructuring processes using two different qualities of hake (Merluccius capensis) muscle, with addition of microbial transglutaminase

AbstractBACKGROUND: Microbial transglutaminase (MTGase) can improve the mechanical and functional properties of restructured fish products without the need of thermal gelation. The present study seeks to determine whether, for different setting times, MTGase activity in restructured hake muscle made with pieces or with homogenised muscle can be affected by the quality of the protein in the raw materials.RESULTS: As regards mechanical properties, samples of both qualities subjected to the two different processes attained a suitable consistency after setting for 24 h at 5 °C. The quality of the protein in the sample is important when pieces are used for restructuring, but not when sample is homogenised. Also, there were strong correlations between residual MTGase activity up to 12 h and mechanical properties and electrophoretic band density. Water binding capacity (WBC) was not significantly altered by MTGase addition.CONCLUSION: The experimental combination of 10 g kg−1 of MTGase, 15 g kg−1 of sodium chloride and 7.5 g kg−1 of sodium caseinate was suitable for the production of minimally processed raw restructured fish products made with two different qualities of fish protein and two different restructuring processes. In the restructured products made with pieces, the protein quality significantly affected final properties, but in finely homogenised product the protein quality was less important. Copyright © 2009 Society of Chemical Industry