Textural properties of low-fat set-type yoghurt depending on mTG addition

Abstract

Our aim was to determine how 0.5-2 U/g non-inactivated mTG affects the pH development and apparent viscosity during fermentation. Furthermore we wished to examine how the enzyme addition could change protein structure, gel strength and sensory characteristics by healthy low-fat set-type yoghurt product. Therefore commercial mTG enzyme preparation was added in different concentrations (0.5-2.0 U/g, in 0.5 U/g steps) to 1.5 % bovine milk simultaneously with DVS starter culture. Our study revealed that enzyme dosage (0.5-2 U/g protein) had no impact on pH development and apparent viscosity during fermentation when manufacturing low-fat (1.5 %) set-type yoghurt. The addition of mTG contributed to 38 % more whey retention with incorporation of β-casein, and caused 44 % higher gel strength up to a level of 1 U/g protein.

Keywords

• fermentation; low-fat yoghurt; transglutaminase; gel strength; apparent viscosity; sensory evaluation