Haake mars 3

The polymer films were cut into rectangular specimens of 20 × 10 mm, and each COS/SA/M²⁺ PDF was tested in tension using a mass spectrometer (TMS-PRO, FTC, Erie, PA, USA) at a stretching rate of 2 mm/min. The tests were carried out at 25 °C using a rheometer (HAAKE MARS III, Thermo, Waltham, MA, USA). The frequency scan experiments were performed in the range of 0.1–100 rad at 1% strain, and the corresponding values of the storage modulus (G’) and loss modulus (G”) were recorded.

The flow behavior of the fermented soymilk was evaluated by a rotational rheometer (Haake Mars III, Thermo Scientific, Karlsruhe, DE) with a plate–plate measuring system (20 mm in diameter, 1 mm gap distance). Flow curves were generated by varying the shear rate from 0.001 to 300 s⁻¹ over 2 min, recording the shear stress and viscosity values at the temperature of 37 °C (during the fermentation step) and 4 °C (during storage). The temperature was controlled by a heating and cooling system (Phoenix II, Thermo Scientific, Karlsruhe, Germany) combined with a Peltier system [27 (link),28 (link)]. In addition, the apparent viscosity was obtained from flow curves at a shear rate of 50 s⁻¹ at 4 °C [29 (link)]. Non-inoculated soymilk was used as the control.

Rheological measurements were performed according to Mota et al. [5 (link)], using a controlled stress rheometer (Haake MarsIII—Thermo Scientific, Karlsruhe, Germany) with a UTC–Peltier system. Frequency sweep tests were performed within the viscoelastic linear region, which was previously defined through a stress sweep test, at 1 Hz using a serrated parallel-plate geometry with a 20 mm diameter. Dough pieces were compacted with a 1.5 mm gap and the edge parts were coated with liquid paraffin to prevent moisture losses during tests. The temperature used for the stress and frequency sweeps was 25 °C.

We investigated the gelation kinetics
of hydrogels by obtaining rheological measurements with a Haake MARS
III controlled-stress rheometer (Thermo Fisher Scientific, Waltham,
MA, USA) equipped with a double cone–plate sensor 60 mm in
diameter at a 2° apex angle (sensor DC60/2° Ti L). For these
assays, we followed the protocol for the preparation of magnetic and
nonmagnetic hydrogels described above and poured the mixture in the
measuring system of the rheometer before adding the water/DMEM mixture.
We then added the water/DMEM mixture directly to the peptide mixture
in the measuring system of the rheometer to induce gelation and immediately
afterward subjected the gelling sample to an oscillatory shear strain
of fixed frequency (1 Hz) and amplitude (γ₀ = 0.001)
while monitoring the resulting viscoelastic moduli as a function of
time. For FF + RGD + MNP + H samples, we applied a 15 kA/m magnetic
field during gelation by using a coil connected to a power supply
placed coaxially to the rheometer axis. The strain amplitude (γ₀ = 0.001) used in these assays was low enough to ensure that
formation of the gel microstructure was unperturbed. Characterization
was carried out at a constant temperature of 37.0 ± 0.1 °C.
We obtained measurements for at least three fresh samples for each
experimental condition.

We investigated the gel kinetics of hydrogels
by means of rheological measurements, using a Haake MARS III controlled-stress
rheometer (Thermo Fisher Scientific, Waltham, MA, USA) provided with
a double cone–plate sensor of 60 mm of diameter and 2°
apex angle (sensor DC60/2° Ti L). With this aim, we followed
the protocol for the preparation of the hydrogels described above
and poured the mixture in the measuring system of the rheometer. Then,
we subjected the gelling sample to oscillatory shear strain of fixed
frequency (1 Hz) and strain amplitude (γ₀ = 0.001),
monitoring the resulting viscoelastic moduli as a function of time
and at a constant temperature of 37.0 ± 0.1 °C. The strain
amplitude used in our work was low enough to ensure that the building
of the gel microstructure was unperturbed.

The small amplitude oscillatory shear (SAOS) behavior of the couscous dough (before sieving) was measured in a controlled-stress rheometer (Haake Mars III—Thermo Scientific, Karlsruhe, Germany) with a UTC-Peltier system. The sample was placed on the bottom of a serrated parallel-plate sensor with a 35 mm diameter (PP35) and a 3 mm gap (previously optimized). After placing the rheometer in the measuring position, with a 3 mm gap between plates, the edges were coated with liquid paraffin to prevent moisture losses during tests. The linear viscoelastic region (LVER) was previously accessed for all the samples, at 6.28 rad/s (1 Hz), through a stress sweep test, and in all the samples, a constant shear stress of 20 Pa was applied to perform the frequency sweep tests (from 0.0628 to 628 rad/s). All rheology measurements were repeated at least three times. Storage moduli (elastic) G′ and loss moduli (viscous) G″ (Pa) data versus angular frequency ω (rad/s) were fitted through power equations, where α′, α″, b′ and b″ are the corresponding fitting parameters (Equations (1) and (2)) [23 (link)].