Rheological properties were determined on three days aged
yogurt variations with a Physica MCR 301 rheometer (Anton Paar,
Messtechnik, Stuttgart, Germany), using a cone-plate geometry
(50 mm in diameter, cone angle of 1
, gap of 0.1 mm). Yogurt
samples (~3.0 g) were carefully placed in the measuring system,
and left to rest for 30 min for structure recovery and temperature
equilibration at 4
C (Physica TEK 150P temperature control and
measuring system). Amplitude sweeps (0.01e100% strain, 1 Hz)
were carried out on the yogurts, and the storage modulus (G
0
), loss
modulus (G
00
) and loss tangent (Tand¼G
00
/G
0) were obtained from
the equipment's RHEOPLUS/32 V2.62 software. Plots ofG
0estrain %
andG
00estrain % were obtained from the experimental data with an
Origin Scientific Graphing and Analysis Software version 7 (OriginLab Corporation, Northampton, MA), and analyzed to determine
the linear viscoelastic and the non-linear viscoelastic regions of the
curves. The linear viscoelastic region on the modulusestrain % plots
was considered as that in which at least three consecutive experimental points of the value ofG
0
orG
00
did not vary with increasing
strain %