Effect of transglutaminase-treated milk powders on the properties of skim milk yoghurt

A novel method of transglutaminase (TGase) treatment for skim milk yoghurt production was investigated. In contrast to previous studies, TGase pre-treated skim milk powder (SMP) was used as protein fortification for yoghurt making, instead of treating the entire yoghurt milk. When the TGase concentration for powder production was increased from 0 to 10 U g−1 protein, the viscosity of stirred skim milk yoghurt produced with addition of TGase-treated SMP increased from 247 to 453 mPas and the serum loss assessed using a centrifugation method decreased from 57.1% to 52.6%. Furthermore, by using enzyme-modified SMP, only half of the protein addition was required to obtain an equivalent viscosity compared to the control. The study showed that crosslinking the caseins by TGase only in the added SMP yields the desired positive effects while allowing for a complete elimination of the residual enzyme activity.