Effect of enzymatic cross‐linking of milk proteins on properties of ice cream with different composition

Abstract

Summary Transglutaminase enzyme (TGase) treatment has been reported to increase the viscosity of milk and gel stiffness of yoghourt and the treatment has been suggested to replace part of the fat and proteins in dairy products. In this study, the effects of TGase on some physical, rheological and sensory properties of ice cream with different fat and stabiliser contents were studied. Five ice‐cream mixes were prepared. Three of them were regular‐fat mixes with 10% fat but vary in the stabiliser (0.7% and 0.2%). The other two mixes were low‐fat mixes, (5% fat and 0.7% stabiliser), a control and treated sample. The mixes were pasteurised (80 °C for 15 min), cooled to 50 °C, homogenised (13.8/3.4 MPa) treated with the enzyme (at 45 °C for 2.5 h) and aged for 24 h at 5 °C before freezing. The viscosity, yield stress and consistency index ( k ) of all mixes were increased by the TGase treatment. The flow behaviour index ( n ) of regular‐fat mixes changed from non‐Newtonian shear thinning ( n = 0.9) to non‐Newtonian shear thicking or dialtant behaviour ( n = 1.26). The flow behaviour index ( n ) of low‐fat mixes did not change by the treatment. On the other hand, the time‐viscosity curves at a constant shear rate of all the enzyme‐treated mixes have changed from thixotropic to rheopectic (time‐thickening) flow. The TGase treated ice creams were superior in all physical and organolyptic properties than their corresponding controls. The enzyme treatment compensated the low‐fat or low‐stabiliser in the ice cream. Moreover, tailored physical properties of ice cream could be obtained by manipulating the mix‐enzyme reaction conditions and amount and type of stabiliser.