Effect Of Transglutaminase Treatment Research Articles

Effect of Transglutaminase Treatment on the Structure and Sensory Properties of Rice- or Soy-Based Hybrid Sausages.

Partial substitution of meat with non-protein sources in hybrid meat products generally leads to a decrease in texture attributes and, consequently, in sensory acceptance. In this study, we investigated the effects of transglutaminase (TG) at two concentrations (0.25% and 0.5%) on the physicochemical, textural, and sensory properties of hybrid sausages formulated with concentrated soy or rice proteins. TG caused a reduction in the heat treatment yield of hybrid sausages, particularly those made with rice protein. pH and color parameters were marginally affected by TG addition. Texture parameters increased substantially with TG, although escalating the TG level from 0.25% to 0.5% did not result in a proportional improvement in texture parameters; in fact, for rice-based hybrid sausages, no difference was achieved for all attributes, while only cohesiveness and chewiness were improved for soy-based ones. TG enhanced the sensory attributes of soy-based hybrid sausages to a level comparable to control meat emulsion, as evidenced by ordinate preference score and projective mapping. Our findings suggest that TG is a viable strategy for enhancing texture and sensory parameters in hybrid sausages, particularly for plant proteins that exhibit greater compatibility with the meat matrix.

Effect of transglutaminase treatment on properties of coconut protein-guar gum composite film

Polysaccharides, proteins and lipids have been utilized for synthesis of polymer matrices to minimize environmental pollution caused by plastic food packaging. Edible coatings are one of the promising alternative in this regard. The coconut protein-guar gum composite films were prepared and studied for their mechanical and barrier properties. Addition of transglutaminase to the composite film forming solution significantly increased the mechanical strength from 1.76 MPa to 3.79 MPa and elongation from 56 mm to 184.87 mm. Improved barrier properties such as water vapour permeability and oxygen transfer rates were observed after treatment of composite films with microbial transglutaminase (MTGase). Differential scanning calorimetric analysis demonstrated an increase in melting temperature with increasing concentration of MTGase. FTIR spectroscopy showed changes in the secondary structure of the protein (amide I and amide II band) and its interaction with the polysaccharide. Major coconut protein having a molecular weight of 53 kDa was not visible in MTGase treated films due to MTGase induced polymerization of protein as analyzed using SDS-PAGE electrophoresis. Scanning electron microscopy exhibited a fibrous microstructure of the surface of the MTGase treated coconut protein guar gum composite films.

Transglutaminase-mediated incorporation of whey protein as fat replacer into the formulation of reduced-fat Iranian white cheese: physicochemical, rheological and microstructural characterization

The effects of transglutaminase treatment (0–2 units/g milk protein) on the chemical composition, textural characteristics, proteolysis and yield of reduced-fat Iranian white cheese (milk fat: 0.4–1.4% w/w) incorporated with whey proteins (0–6 g/L milk) were investigated. Enzyme-mediated inclusion of whey proteins in the reduced-fat cheese caused a noticeable increase in moisture to protein (M:P) ratio with concomitant decease in the hardness rheological parameters of fracture stress and Young’s and storage (G’) moduli. However, increase in concentrations of whey proteins or/and transglutaminase enzyme above a critical level led to formation of a cheese matrix with lower moisture content and greater values of hardness indices. Whey protein addition and transglutaminase treatment resulted in the same trends of changes in proteolysis rate and cheese yield as in cheese softness. Response surface method (RSM) suggested that the enzymatic incorporation of 4.2 g deliberately added whey proteins to 1 L of milk (1.04% w/w fat) into the cheese matrix using 0.833 unit transglutaminase per gram milk protein would provide a reduced-fat product with the softest texture and the highest yield. The scanning electron micrographs showed formation of honeycomb structures in the protein matrix of the reduced-fat sample with optimum formulation.

The effect of transglutaminase treatment on the physico-chemical properties of skim milk with added ethylenediaminetetraacetic acid

The influence of transglutaminase (TG) treatment on the changes in the physico-chemical properties of reconstituted skim milk (10 wt%) with different amounts of added ethylenediaminetetraacetic acid (EDTA) (0–50 mM) was studied. The partition of salts (Ca, Mg, K, Na and inorganic phosphate) was determined experimentally by atomic absorption and emission spectroscopy, colorimetry and 31P-nuclear magnetic resonance spectroscopy, and calculated with a model of the salt partition in milk based on equilibrium thermodynamics. Hydrodynamic radius, skim milk viscosity and casein micelle medium resolution substructure were measured by dynamic light scattering, rheology, and small-angle X-ray scattering (SAXS), respectively. TG treatment of milk did not influence the partition of salts upon the addition of EDTA as TG crosslinking is unlikely to disrupt the phosphate centre motifs on the short exon-encoded amino acid sequences on caseins. However, TG treatment prevented full dissociation of casein micelles when >15 mM EDTA was added, and induced higher viscosity increase than TG-untreated milk upon addition of EDTA. In accordance with the particle sizing results, SAXS demonstrated that TG treatment reduced the extent of EDTA-induced micellar disruption, as compared to milk without TG treatment.

Effect of transglutaminase treatment on the properties of cast films of soy protein isolates

The objective of this work was to investigate the effect of microbial transglutaminase (MTGase) treatment on the properties and microstructures of soy protein isolate (SPI) films cast with 0.6 plasticizer per SPI (g g −1) of glycerol, sorbitol and 1:1 mixture of glycerol and sorbitol, respectively. Tensile strength (TS), elongation at break (EB), water vapor transmission rate (WVTR) or water vapor permeability (WVP), moisture content (MC), total soluble matter (TSM), lipid barrier property and surface hydrophobicity of control and MTGase-treated films were evaluated after conditioning film specimens at 25 °C and 50% relative humidity (RH) for 48 h. The treatment by 4 units per SPI (U g −1) of MTGase increased the TS and surface hydrophobicity by 10–20% and 17–56%, respectively, and simultaneously significantly ( P ≤ 0.05) decreased the E, MC and transparency. The WVTR or TSM of SPI films seemed to be not significantly affected by enzymatic treatment ( P > 0.05). The MTGase treatment also slowed down the moisture loss rate of film-forming solutions with various plasticizers during the drying process, which was consistent with the increase of surface hydrophobicity of SPI films. Microstructural analyses indicated that the MTGase-treated films of SPI had a rougher surface and more homogeneous or compact cross-section compared to the controls. These results suggested that the MTGase treatment of film-forming solutions of SPI prior to casting could greatly modify the properties and microstructures of SPI films.

Effects of transglutaminase treatment on functional properties and probiotic culture survivability of goat milk yogurt

The objectives of this study were to investigate the effects of enzymatic cross-linking of milk proteins on the functional properties and probiotic culture survivability of goat milk yogurt. After pre-incubation (50 °C, 1 h) of the milk with microbial transglutaminase [MTGase, 0–4 units (U)/g protein] and subsequent heat inactivation (75 °C, 5 min), yogurt was prepared by inoculating the milk with a commercial probiotic yogurt starter containing probiotic cultures ( Lactobacillus acidophilus, Bifidobacteria, and Lactobacillus subsp. casei) and incubating the inoculated milk at 43 °C for 5 h. Compared to the untreated control trial, pretreatment of the milk with MTGase (2 and 4 U/g protein) increased ( P < 0.05) the viscosity and decreased the syneresis of yogurt samples. The effect of enzyme treatment was more significant in improving the viscosity of yogurt compared to the method of increasing total solids (TS) in the milk. No significant differences in basic nutrient contents between control and enzyme-treated samples were observed. The probiotic cultures were relatively stable in the goat milk yogurt and their populations remained above 10 6 CFU/g during the 8-week storage period at 4 °C. No significant differences in rate of change of population of all the three probiotic cultures were observed between the control and the MTGase treated groups. Microbiological analysis shows that the enzymatic cross-linking of proteins seems to have a positive role in the survivability of the probiotic cultures, which requires further investigation. Scanning electron microscopic studies revealed that the microstructure of the enzyme-treated samples appeared denser than the control, suggesting that pretreatment of milk by MTGase could be used to improve the microstructure of the yogurt gel. Results of this study indicate that enzymatic cross-linking of milk proteins by MTGase appears to be an effective means for improving the functional properties of goat milk yogurt. MTGase treatment may be a useful method in the production of probiotic goat milk yogurt products.

β-Casein micelles; cross-linking with transglutaminase

Abstract The association behaviour of β-casein was markedly affected by transglutaminase (TG)-catalysed crosslinking. Treatment of β-casein with TG at 35 °C eliminated the ability of β-casein micelles to monomerise on cooling, while β-casein pre-treated with TG at 0 °C was unable to associate into micelles when the temperature was increased to 40 °C. The effect of TG when incubated with β-casein at 35 °C is attributed to intermolecular crosslinking. While the effect of TG when incubated with β-casein at 0 °C is due to intramolecular crosslinking which inhibits micellisation by reducing molecular mobility and/or causes an alteration in the charge distribution of β-casein. The effect of TG treatment at 0 or 35 °C on some of β-casein's physico-chemical properties (calcium sensitivity, hydrophobicity and viscosity) was studied and shown to be altered by TG treatment at both 0 and 35 °C. Changes in the physico-chemical properties of TG-treated β-casein appear to be due, in part, to charge modification.

Short Communication: Influence of Transglutaminase on the Heat Stability of Milk

Skim milk powders were prepared from control and transglutaminase-treated skimmed milk. The heat stability of reconstituted transglutaminase-treated skimmed milk (9.0% total solids) was markedly increased in the pH region of minimum stability (pH 6.8 to 7.1) compared with control milk, while the heat stability of reconstituted concentrated transglutaminase-treated skimmed milk (22.5% total solids) increased progressively as a function of pH relative to control milk. The effect of transglutaminase treatment on the heat stability of skimmed milk may have commercial applications, but extensive research is necessary to gain a better understanding of the mechanism by which transglutaminase improves heat stability.

Effect of transglutaminase treatment on the functional properties of native and chymotrypsin-digested soy protein

Native and chymotrypsin-digested soy protein were polymerized by transglutaminase (TGase). SDS-PAGE pattern of the polymerized proteins showed that TGase treatment resulted in proteins of higher molecular mass above the stacking gel. The free amino groups of the polymerized proteins were greatly reduced. The solubility of the protein polymer was greatly improved at pH 2 and pH 8–12 whereas, at pH 4 and 6, it was least soluble. The solubility of the digest polymer was significantly improved at all pH levels, except pH 4. The protein polymer started to coagulate when the heating temperature exceeded 50°C. The digest polymer, on the other hand, resisted heat-induced aggregation up to 60°C; thereafter, its solubility declined slightly. The emulsifying and foaming properties of the digest polymer were greatly improved compared to the protein polymer. The protein polymer was observed to form a harder gel than the digest polymer.

Effect of transglutaminase treatment on the glass transition of soy protein.

The effect of microbial transglutaminase (MTG) treatment on the glass transition temperature (T(g)) of two fractions which were isolated from a soy protein sample was studied. The T(g) of each fraction measured by differential scanning calorimetry was lowered by the MTG treatment, which generated cross-links in the samples, and this result agreed with the result of dynamic mechanical analysis. From the (1)H NMR measurement, the line width of the (1)H signal of the MTG-treated sample was observed to be greater than that of the MTG-nontreated sample at similar water content, which implied that there was relatively more immobilized water in the MTG-treated sample. The MTG treatment seemed to cause the increment in immobilized water, which might affect the T(g) of the soy protein sample.