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Microwave-assisted cross-linking of milk proteins induced by microbial transglutaminase
Chun-Chi Chen1,2, Jung-Feng Hsieh1,2
1Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan.
Abstract:
We investigated the combined effects of microbial transglutaminase (MTGase, 7.0 units/mL) and microwave irradiation (MI) on the polymerization of milk proteins at 30 °C for 3 h. The addition of MTGase caused the milk proteins to become polymerized, which resulted in the formation of components with a higher molecular-weight (>130 kDa). SDS-PAGE analysis revealed reductions in the protein content of β-lactoglobulin (β-LG), αS-casein (αS-CN), κ-casein (κ-CN) and β-casein (β-CN) to 50.4 ± 2.9, 33.5 ± 3.0, 4.2 ± 0.5 and 1.2 ± 0.1%, respectively. The use of MTGase in conjunction MI with led to a 3-fold increase in the rate of milk protein polymerization, compared to a sample that contained MTGase but did not undergo MI. Results of two-dimensional gel electrophoresis (2-DE) indicated that κ-CN, β-CN, a fraction of serum albumin (SA), β-LG, α-lactalbumin (α-LA), αs1-casein (αs1-CN), and αs2-casein (αs2-CN) were polymerized in the milk, following incubation with MTGase and MI at 30 °C for 1 h. Based on this result, the combined use of MTGase and MI appears to be a better way to polymerize milk proteins.
Insights
Microbial transglutaminase (MTGase) and microwave irradiation (MI) effectively polymerize milk proteins, forming higher molecular-weight components. Combining MTGase and MI significantly accelerates this polymerization process.
Area of Science:
- Food Science
- Biochemistry
- Protein Chemistry
Background:
- Milk proteins are susceptible to modification and polymerization.
- Enzymatic and physical treatments can alter protein structure and function.
Purpose of the Study:
- To investigate the synergistic effects of microbial transglutaminase (MTGase) and microwave irradiation (MI) on milk protein polymerization.
- To determine the impact of combined MTGase and MI treatment on the molecular weight and composition of milk proteins.
Main Methods:
- Milk protein samples were treated with MTGase (7.0 units/mL) at 30°C for 3 hours.
- Combined treatment involved MTGase and microwave irradiation.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional gel electrophoresis (2-DE) were used for analysis.
Main Results:
- MTGase alone induced milk protein polymerization, forming components >130 kDa.
- SDS-PAGE showed significant reductions in β-lactoglobulin, αs-casein, κ-casein, and β-casein content.
- Combined MTGase and MI treatment resulted in a 3-fold increase in the polymerization rate compared to MTGase alone.
- 2-DE confirmed polymerization of multiple milk proteins, including caseins, β-lactoglobulin, and serum albumin, under combined treatment.
Conclusions:
- The combination of MTGase and MI is a highly effective method for milk protein polymerization.
- This synergistic approach significantly enhances the rate and extent of protein polymerization compared to MTGase treatment alone.
- The findings suggest a promising strategy for modifying milk protein functionalities.
