Introduction: Microbial Transglutaminase Enzyme (MTG), known as EC 2.3.3.13, is extracted and purified from a bacterial species called Streptoverticillium. The optimum activity of this enzyme occurs at a pH range of 6 to 7, and its ideal operating temperature lies between 37°C and 50°C. MTG belongs to the class of transferase enzymes and catalyzes covalent cross-links between the amino acids glutamine and lysine in proteins, resulting in the formation of high molecular weight polymers. These intra- and intermolecular cross-links in proteins improve the texture and quality of food products and lead to the creation of novel proteins with unique and desirable properties.
Milk and dairy products are among the most valuable food sources, providing nearly all the essential nutrients required for human growth and survival. Each year, the production volume of milk and dairy products fluctuates due to various factors such as climate, economic conditions, and policy decisions. Given the nutritional importance of milk and its derivatives in dietary patterns, these products have consistently attracted the attention of governments in many countries, including Iran.
Methods: Effect of Microbial Transglutaminase Enzyme on Traditional Kefir Beverage: The addition of 0.04% microbial transglutaminase enzyme to kefir resulted in a significant 40% reduction in syneresis during 30 days of refrigerated storage. Analysis of kefir's aromatic compounds using solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) revealed that storage time had a significant impact on the variation of these compounds—some decreased while others increased. However, enzyme addition had no notable effect on the aromatic profile, except for an increase in alcohol content. Total levels of alcohols and acids rose during storage, with alcohol levels slightly higher in the enzyme-treated sample. In contrast, ketones, aldehydes, and esters decreased in both control and enzyme-treated samples. Carbon dioxide, which combines with ethanol to create kefir’s distinctive flavor, increased in both samples over the storage period.
Effect of Microbial Transglutaminase Enzyme on Milk: Skim milk was divided into three portions, each incubated with microbial transglutaminase (TGM) under different thermal and processing conditions. After incubation, the enzyme was inactivated by heat treatment, and the samples were analyzed. Preliminary evaluation indicated that adding 2 units of enzyme per gram of protein and incubating at 40°C for 2 hours provided optimal conditions for modifying milk proteins.
Effect of Microbial Transglutaminase Enzyme on Cream Cheese: The combined effect of microbial transglutaminase enzyme (MTG) and gelatin on the physical, rheological, and sensory properties of low-fat cream cheese was investigated. The primary goal was to improve texture and consumer acceptance in a product that typically suffers quality loss due to reduced fat content. Cream cheese samples were prepared with varying amounts of MTG and gelatin, and then evaluated for parameters such as consistency, water-holding capacity, texture firmness, overall acceptability, and other sensory attributes.
Effect of Microbial Transglutaminase Enzyme on Strained Yogurt: This study examined the impact of different concentrations of microbial transglutaminase enzyme (0.1%, 0.2%, and 0.3%) on the sensory and rheological properties of strained yogurt. The enzyme was added to milk prior to homogenization and pasteurization, and samples were incubated at 50°C for 30 minutes. Subsequently, pasteurization and starter culture inoculation were carried out to produce yogurt, with a control group tested without enzyme addition.
Results: Effect of Microbial Transglutaminase Enzyme on Traditional Kefir Beverage: Analysis of kefir’s aromatic compounds using solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC-MS) revealed that storage time had a significant impact on the variation of these compounds—some decreased while others increased. However, the addition of the enzyme had no notable effect on the aromatic profile, except for an increase in alcohol content. Total levels of alcohols and acids rose during storage, with alcohol levels slightly higher in the enzyme-treated sample. In contrast, ketones, aldehydes, and esters decreased in both the control and enzyme-treated samples. Carbon dioxide, which combines with ethanol to create kefir’s distinctive flavor, increased in both samples during storage. Overall, the findings indicated that microbial transglutaminase significantly reduced syneresis during storage without meaningfully altering the aromatic composition of kefir.
Effect of Microbial Transglutaminase Enzyme on Milk: Results showed that TGM led to the formation of high molecular weight compounds (ranging from 55 to 194 kDa), but had no significant effect on the thermal stability of milk proteins, preserving the characteristics of fresh milk. Additionally, protein modification with TGM resulted in a notable increase in alcohol content and enhanced stability of mineral complexes. These findings suggest that commercial transglutaminase can be used as an innovative approach to preserve nutritional value and improve the functional properties of milk in industrial processing.
Effect of Microbial Transglutaminase Enzyme on Cream Cheese: The results demonstrated that the addition of MTG, through the formation of cross-links between proteins, along with the use of gelatin as a texture-enhancing agent, led to increased firmness, reduced syneresis, and improved sensory attributes of low-fat cream cheese. Ultimately, an optimal combination of these two ingredients was proposed as a suitable fat replacer for producing high-quality cream cheese.
Effect of Microbial Transglutaminase Enzyme on Strained Yogurt: The findings showed that the addition of transglutaminase significantly improved the sensory properties of yogurt, reduced syneresis, and increased water-holding capacity. These results indicate that the enzyme could serve as an effective alternative to powdered milk in enhancing the consistency and quality of strained yogurt.
Conclusion: Based on observations regarding the impact of microbial transglutaminase on dairy products, the resulting items demonstrated that the addition of this enzyme enhances the texture, type, and overall quality of dairy, allowing for the production of superior and healthier products with greater environmental compatibility. Moreover, improving the quality of dairy and dairy-based industries contributes positively to public health and helps prevent potential adverse effects associated with dairy consumption. Given the global significance of dairy products, there is a growing need to offer optimized solutions, and such innovative approaches can support both human health and environmental sustainability worldwide.