Characterization of Transglutaminase Isolated from Rosemary Leaves, and Development of Chemical, Rheological and Sensory Properties of Kareish Cheese Made with Transglutaminase.

Purification of transglutaminase (TGase) isolated from leaves of rosemary (Rosmarinus officinalis L) carried out by three steps including protein precipitation with using ammonium sulfate (40-80%), followed by elution into ion exchange column (DEAE-Sephadex A-50). The further purification of dialyzed fractions were applied on Sephadex G-100. The purified enzyme eluted from gel filtration column (Sephadex G-100) had 26.51 yield associated with increased about 6.3 in fold of purification. The optimum pH for rosemary TGase was 6.0 and the highest activity of this enzyme associated with incubated at 60°C for catalytic reaction of Z-Gln-Gly and hydroxylamine. The TGase was stable following heating up to 70 for 15 min, while a complete loss of TGase activity was associated with exposing to 90°C for 5 min. The exposure of TGase to salt concentrations ranging from 2-4% did not effect on its activity. However increased NaCl concentrations of 5-14% caused a decline in the activity. The effects of cross-linked by different concentrations of TGase (2.5, 5 and 10U/g protein) on chemical, sensorial and textural of Kareish during 15 days of storage period were studied. The Kareish cheese chemical composition presented to be affected by using different concentration of TGase. The moisture and yield were the highest values in cheese made by 10U/g protein of TGase, while pH was the lowest value in the same treatment, compare with other concentrations of TGase and control. Kareish cheese made by using 10 10U/g protein of TGase receive high scores in sensorial properties. Hardness, adhesiveness, gumminess and chewiness values were decreased significantly (P> 0.05) in Kareish cheese made with TGase than control.