Discovery hr2 hybrid rheometer

Stress-strain measurements. Stress-strain curves were measured with a Discovery HR-2 hybrid rheometer from TA Instruments. The films were stretched 2 μm/s until rupture. The environmental temperature was set to 25°C.
Thermogravimetric measurements (TGA). Thermogravimetric measurements were carried out with a Mettler Toledo TGA 850. The samples were heated from 25°C to 800°C at a rate of 10°C/min under nitrogen atmosphere.
Oscillatory modulus measurements. The films’ moduli were measured with a DMAQ800 from TA Instruments. The moduli were measured from −50°C to 200°C with a heating rate of 5°C/min. The strain amplitude was 0.5% with frequency of 1 Hz.
Differential scanning calorimetry (DSC). Calorimetric measurements were conducted on a TA Instruments DSC Q2000 differential scanning calorimeter. The measurement programs were adjusted based on the decomposition temperature and expected T_g of the sample. Heating and cooling rates were always 20°C/min. Heating was started from −80°C.

The viscosity of aquafaba solutions at pH 5 with and without addition of XG and HPMC (0 to 0.6% by mass) and 86.4 g sugar was analyzed using the methods of [10 (link)] with modification. In addition, the viscosity of egg white (EW) with 86.4 g sugar was analyzed for comparison. All samples were stirred using magnetic stir bars at room temperature for 1 h to allow solubilization of sugar and gums. Prior to analysis, samples were sonicated using an ultrasonic bath (Cole-Parmer, Vernon Hills, IL, USA) for 20 min to remove bubbles formed during mixing. A Discovery HR-2 hybrid rheometer (TA Instruments, New Castle, DE, USA) with TRIOS software 5.2 (TA Instruments, New Castle, DE, USA) was used for analyses. Approximately 2 mL of samples were dispensed onto the rheometer plate, then a 60 mm 2.0° cone (TA Instruments, UK) was lowered to the trim gap at 105 µm where sample amount was adjusted if necessary to extend to edge of the probe. The cone was lowered to the geometry gap at 52 µm and samples were then tested using a linear flow rate test at 25 °C. The samples went through a conditioning step with a 20 s soak time and a 60 s period of pre-shear. Next, samples underwent a flow ramp at 25 °C while shearing occurred over 840 s at a rate of 0.1 s⁻¹ to 100 s⁻¹, with measurements recorded every 5 s. Samples were analyzed in triplicate. A power law model was fit with the TRIOS software.

A rheometer (Discovery HR-2 Hybrid rheometer, TA Instruments, New Castle, DE, USA) equipped with a cone plate (40 mm diameter/2° angle), was used to measure the apparent viscosity (η) with varying shear rate (s⁻¹) from 0.1 s⁻¹ to 100 s⁻¹, for each of the six yogurt samples in Table 1. The flow behavior index (n) and consistency index (K) were calculated by fitting the data to the modified power-law (η = K γⁿ⁻¹), using the rheology software TRIOS v4.2.1.36612 (TA Instruments, New Castle, DE, USA). A pre-shear of 100 s⁻¹ for 10 s was applied to each sample, prior to measurements. All measurements were performed in triplicate for each sample at 10 °C, which was also the serving temperature for sensory analysis. A texture analyzer (TA.HD plus, Stable Microsystems, New Castle, DE, USA) was used to measure gel firmness with a 5 kg load cell, using a trigger force of 1 g and a 10 mm cylindrical probe with each sample analyzed five times [30 (link)].

Instrument rheological analysis of all aquafaba samples was performed using the methods of Alsalman et al. [10 (link)] with modification. Aquafaba samples were evaluated post-steeping and before freezing. A Discovery HR-2 hybrid rheometer (TA Instruments, New Castle, DE, USA) with TRIOS 5.2 software (TA Instruments, New Castle, DE, USA) was used for analyses. For each replicate, approximately 2 mL of samples were dispensed onto the rheometer plate. A 60 mm 2.0° cone (TA Instruments, Elstree, UK) was lowered to the trim gap at 105 µm, where the sample amount was adjusted if necessary to extend to the edge of the cone. The cone was then lowered to the final gap of 52 µm above the plate. Samples were then evaluated using a linear flow rate test. First, samples went through a conditioning step of 20 s soak time and a 60 s period of pre-shear. Next, samples underwent a shear flow ramp of 0.1 s⁻¹ to 100 s⁻¹ over an 840 s period, while the temperature was maintained at 25 °C and points sampled every 5 s. Each treatment group was analyzed in triplicate, with three replicates of each sample. A power law model was fit to the shear stress versus shear rate results using TRIOS 5.2 software.