Impact of Transglutaminase on the Functionality of Milk Protein Concentrate and Micellar Casein Concentrate

Milk protein concentrate (MPC) and micellar casein concentrate (MCC) are products manufactured using ultrafiltration (UF) and microfiltration (MF) respectively. The presence or absence of constituents in MPC and MCC particularly, intact CN, serum proteins (SP), lactose, and minerals influence the functional properties of these ingredients. In some applications MPC and MCC have inferior functionality relative to rennet casein. The use of a cross-linking enzyme transglutaminase (TGase) has the potential to modify the physical properties of MPC or MCC and may improve their functional properties relative to rennet casein. The objective of this research was to determine the impact of TGase on the functionality of MCC and MPC. Three lots of MCC and MPC retentate were produced with similar TN/TS ratio. Each replicate of retentate was divided into 3 equal portions. Each portion was treated with TGase included TGase (0.3 U/g of protein), TGase (3.0 U/g of protein), and no TGase addition. All the retentates were incubated for 25 min at 50°C, heat treated at 72°C for 10 min, cooled to 4°C and then spray dried. Various functional tests were used for characterization of MCC and MPC. The treatment powders were tested in yogurt, process cheese product (PCPloaf) and imitation mozzarella cheese (IMC) formulations. There were significant (P ≤ 0.05) differences in all of the compositional parameters except fat and CN for the MF and UF retentate. Capillary gel electrophoresis (CGE) analysis indicated crosslinking within and among casein and whey protein fractions. At the higher TGase level some degree of hydrolysis was also observed. The TGase crosslinking significantly (P ≤ 0.05) increased heat and alcohol stability, solubility index, emulsifying capacity, transition temperature, stretchability and significantly (P ≤ 0.05) decreased Schreiber melt area, RVA remelt in both MCC and MPC treatments. The results demonstrate that TGase treatment significantly (P ≤ 0.05) impacts the functionality and modify the melt, stretch and textural characteristics of MCC and MPC in IMC and PCP applications