Levels Of Microbial Transglutaminase Research Articles

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.

Production of low-salt restructured Mediterranean horse mackerel (Trachurus mediterraneus) using microbial transglutaminase/caseinate system

Low-salt restructured fish products without cooking were prepared from Mediterranean horse mackerel using varying levels of NaCl (0-control, 10 and 20 g/Kg) and microbial transglutaminase (MTG) (0-control, 5 and 10 g/Kg). Restructured products with the highest textural strength and sensory acceptability were obtained at 1% MTG and 2% NaCl. The use of MTG made the low salt (1%) product comparable to one prepared with 2% NaCl only. WHC was not affected by MTG at 0% NaCl. The microbiological analysis (Total Viable Bacteria, Shewanella putrefaciens, Pseudomonas spp. and Enterobacteriaceae) suggests a relatively short shelf-life (< 4 days) at refrigeration temperature (2±2ºC). The cooked restructured products received more favourable scores with increased levels of MTG and NaCl.

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.

Thermal and physicochemical properties of red tilapia (Oreochromis niloticus) surimi gel as affected by microbial transglutaminase

Thermal and physicochemical properties of red tilapia (Oreochromis niloticus) surimi gel incorporated with different levels of microbial transglutaminase (MTGase) were investigated. Surimi samples mixed with various concentrations of MTGase were subjected to two-stages heating (at 45°C followed by 90°C) to prepare surimi gel. Samples formulated with 0.30 MTGase (units/g surimi) showed the highest breaking force and deformation, and lowest expressible water content among treatments. Highest storage modulus was found in the gels mixed with 0.30 MTGase (units/g surimi). Compared with control surimi gel, addition of microbial transglutaminase to levels 0.10, 0.20 and 0.30 (units/g surimi) increased the enthalpy and maximum transition temperature of myosin. Results suggest that up to 0.30 MTGase (units/g surimi) could improve texture, colour, water-holding capacity, elasticity and thermal stability of red tilapia surimi gel.

Effect of transglutaminase on quality characteristics of a value-added product tilapia wastes.

The aim of this work was to evaluate the physico-chemical, instrumental color and texture, and sensory qualities of restructured tilapia steaks elaborated with small sized (non-commercial) tilapia fillets and different levels of microbial transglutaminase (MTG). Four concentrations of MTG were used: CON (0% MTG), T1 (0.1% MTG), T2 (0.5% MTG), and T3 (0.8% MTG). In addition, bacterial content and pH shifts were also evaluated during 90days of frozen storage. The different levels of MTG did not affect (P > 0.05) either the proximate composition of the restructured tilapia steaks or the bacterial growth during the frozen storage. MTG improved (P < 0.05) cooking yield and instrumental hardness and chewiness as well as sensory (salty taste, succulence and tenderness) attributes; strongly contributing to greater overall acceptance. Therefore, restructured tilapia steaks manufactured with MTG are potentially valued-added products with good consumer acceptance and better purchase-intention than steaks formulated with 0% MTG.

Dependence of microbial transglutaminase on meat type in myofibrillar proteins cross-linking

The objectives of this study were to determine the factors that cause differences in the improvements of gel strength and ε(γ-glutamyl)lysine (G-L) content in chicken and beef (Japanese black cattle) myofibrillar proteins after adding microbial transglutaminase (MTG). As the amount of MTG added increased, the breaking strength increased progressively ( p < 0.01) in chicken and beef samples, with the exception of chicken samples treated at 40 °C. The values of elasticity in the chicken samples were lower than those of the beef samples ( p < 0.01). Surprisingly, the elasticity level, ε(γ-glutamyl)lysine contents and myosin heavy chain (MHC) band sizes of chicken and beef at all levels of MTG were significantly different ( p < 0.01). The results of this study suggest that MTG activity was affected by MTG inhibitors; that MTG develops the texture of myofibrils differently in different species. However, the activity is limited and inconstant among meat proteins, as suggested by the data collected from the chicken samples. As a result, when the transferable amino acid residues are depleted (cross-linked) by MTG activity, the function of MTG will be insignificant. The correlation between MTG and different sources of meat protein is quite unstable but it is strong, which was observed when chicken and beef responded differently to MTG because their chemical and physiological properties were different. The remarkable rate of formation of cross-linked proteins and the discrepancy between the expected and observed amount of dipeptide raises the possibility that there are enzymes capable of reversing the reaction induced by transglutaminase in chicken and beef myofibrils. In summary, our results suggest that access of MTG to chicken and beef myofibrils is different because it depends on physiological (muscles and their fibre types), biological (substrates) and biochemical (inhibitors and amino acids) variables.

Effect of Microbial Transglutaminase on Spaghetti Quality

To examine the potential application of microbial transglutaminase (MTG) on semolina dough properties and quality of raw and cooked spaghetti, the effects of various MTG addition levels on the solubility of proteins, SDS-PAGE pattern of semolina dough proteins, and textural and structural properties of raw and cooked spaghetti were investigated using semolina from a high-protein good variety (MACS 1967) and a low-protein poor variety (PDW 274) durum wheat. To increase the concentration of lysyl residues and possibly enhance the extent of cross-linking of protein matrix by MTG, a commercial soy protein isolate (SPI) was added at a level of 3% (w/w) in combination with MTG, and its effect on semolina dough properties and spaghetti quality was investigated. The addition of MTG significantly decreased the solubility of semolina dough proteins. SDS-PAGE results showed that with increasing levels of MTG, a progressive decrease in the intensity of the bands corresponding to molecular weight of around 66 kDa was observed. Protein cross-linking reaction catalyzed by MTG resulted in changes in dough properties, dry spaghetti quality, cooking quality characteristics, and microstructure of cooked spaghetti. However, the quality improvements were more evident in spaghetti from the poor variety PDW 274 than from the good variety MACS 1967. The results also showed the ability of MTG in the formation of heterologous polymers between SPI and durum wheat proteins to improve the quality of spaghetti samples.

Raman spectroscopy study of the structural effect of microbial transglutaminase on meat systems and its relationship with textural characteristics

Raman spectroscopy and texture analysis (TPA) studies were carried out to determine the effect of adding different levels of microbial transglutaminase (MTGase) to meat systems. This addition produced a significant (p<0.05) increase in hardness, springiness and cohesiveness in the meat systems. Raman spectroscopy analysis revealed the occurrence of secondary structural changes in meat proteins due to MTGase. Modifications in the amide I (1650–1680cm−1) and amide III (1200–1300cm−1) regions indicated a significant (p<0.05) decrease in α-helix content, accompanied by a significant (p<0.05) increase in β-sheets and turns due to the addition of the enzyme to meat systems. Significant (p<0.05) correlations were found between these secondary structural changes in meat proteins and the textural properties (hardness, adhesiveness, springiness and cohesiveness) of meat systems.

Gelling properties of white shrimp ( Penaeus vannamei) meat as influenced by setting condition and microbial transglutaminase

The properties of white shrimp ( Penaeus vannamei) gel added with different levels of microbial transglutaminase (MTGase) and subjected to setting at 25 °C for 2 h or 40 °C for 30 min, prior to heating at 90 °C for 20 min were studied. Breaking force of gels with and without setting increased with increasing MTGase amount added ( P < 0.05 ). However, no changes in deformation in all samples were noticeable ( P > 0.05 ). Directly heated gels showed the lower breaking force than those with prior setting at all MTGase levels added ( P < 0.05 ). Generally, gels prepared by setting at 25 °C exhibited the greater breaking force than those set at 40 °C, possibly associated with the appropriate protein structure for cross-linking at 25 °C and greater degradation at 40 °C as evidenced by a greater trichloroacetic acid soluble peptide content ( P < 0.05 ). Sodium dodecyl sulfate polyacrylamide gel electrophoretic study revealed that myosin heavy chain (MHC) underwent polymerization to a higher extent in the presence of MTGase, but the strengthening effect on gel was dependent on setting temperature. Regardless of setting condition, microstructure of gel added with MTGase was finer with a smaller void, compared with those of gel without MTGase. Therefore, setting temperature played an essential role in gel property of white shrimp meat added with MTGase.

Determination of the effect of microbial transglutaminase on technological properties of common carp (Cyprinus carpio L.) meat

The aim of this study was to evaluate the effect of microbial transglutaminase (TG) on processed meat of common carp (Cyprinus carpio L.). Three levels of microbial transglutaminase (0.5, 1.0 and 1.5%) combined with three levels of NaCl (0, 1 and 2%), added to support the binding reaction, were examined. For the evaluation of quality changes in restructured fish meat, we used the textural property hardness and water holding capacity (WHC). The results confirmed a strong improvement of texture and water holding capacity after the addition of transglutaminase and salt, whereas the addition of 1% TG + 1% NaCl seems to be the best combination from the economic aspect. Another increase in the addition of TG and NaCl to the fish meat did not lead to further improvement of qualitative properties, as it was in the groups with 0% and 1% NaCl. &amp;nbsp;

Using Salt and Microbial Transglutaminase as Binding Agents in Restructured Fish Products Resembling Hams

ABSTRACT: Restructured products were obtained from fish paste of silver carp (Hypophthalmichthys molitrix) by massaging and cooking in ham presses. Assayed were 3 levels of salt (0 as control, 1, or 2%) and 3 levels of microbial transglutaminase (MTGase). Changes on solubility of pastes, mechanical properties, WHC, and SDS‐PAGE of the cooked product were evaluated. MTGase needed the addition of NaCl to improve the mechanical properties of these restructured products. Better textural properties were obtained with 2% NaCl. Adding 0.3% of MTGase and 1% NaCl obtained a low‐salt, homogenous restructured meat block with 2773 g hardness, 29106 g/cm gel strength, 0.233 cohesiveness, and 11.6% extracted water.