Phoenix 2

Rheological measurements of the obtained samples were carried out by means of a rotational rheometer, Haake MARS III (Thermo Scientific, Karlsruhe, Germany), 5 days after their preparation using a 60-mm diameter parallel plate geometry (PP60). The temperature was controlled by a Peltier system in combination with a water bath system (Phoenix II, Thermo Scientific, Karlsruhe, Germany). The samples (2.9 mL) were carefully poured onto the surface of the lower plate and the upper plate was lowered to 1 mm gap distance. Before testing, samples were left equilibrating for 5 min to allow for mechanical and temperature equilibration. Flow curves were made in control rate mode (CR) by varying the shear rate (0.1–1000 s⁻¹) at 25 °C. The average size of the dispersed phase of nanoformulations used for antifungal activity was determined through dynamic light scattering (DLS) using a Malvern UK Zetasizer-Nano ZS 90 instrument (Malvern Instrument Ltd., Worcestershire, UK) operating with a 4 mW He-Ne laser (633 nm). The average diameter was measured at fixed detector angle of 90 by cumulant analysis of the autocorrelation function using software provided by the manufacturer. Before analysis samples were diluted 1:10 with ultra-pure water to avoid multiple scattering effects.

The rheometer, Haake MARS III (Thermo Scientific, Karlsruhe, Germany), was used for the rheological characterization. All measurements were made at 25 °C, and the temperature was controlled by a Peltier module TM-PE-P coupled with a liquid bath module (Phoenix II, Thermo Scientific, Karlsruhe, Germany). The samples (2.9 mL) were poured onto the surface of the lower plate, and the upper plate was lowered to 1 mm gap distance. Before testing, samples were left equilibrating for 10 min to allow for mechanical and temperature equilibrium.
Flow curves and thixotropic behavior were studied through rotational tests. Both tests were realized in controlled rate mode (CR). Thixotropy curves were obtained through hysteresis loop experiments carried out in three steps: (1) Upward curve was made by varying the shear rate from 0 to 100 s⁻¹ in 100 s, (2) plateau curve at the maximum shear rate (100 s⁻¹) for 30 s, (3) downward curve by varying the shear rate from 100 to 0 s⁻¹ in 100 s.
Oscillatory dynamic tests: The range of linear viscoelasticity (LVE) was determined through amplitude sweep test at 1 Hz of frequency, and frequency sweep test was made in controlled deformation and a frequency range from 0.01 to 10 Hz.

The PCS measurements were performed on a custom-built fixed-angle setup (scattering angle $\theta$ : 60°) utilizing a He–Ne Laser (wavelength $\lambda =632.8$ nm, 21 mW, Thorlabs, Newton, MA, USA) and two photomultipliers (ALV/SO-SIPD, ALV-GmbH, Langen, Germany) in a pseudo-cross-correlation configuration. The signal was correlated with an ALV-6010 multiple-tau correlator (ALV GmbH, Langen, Germany). Subsequently, the intensity–time correlation functions were converted to the field–time correlation function $g^1\left(t\right)$ and analyzed using the CONTIN software [62 (link)]. However, an analysis using a second-order cumulant function also leads to the same result within the exp. precision. The temperature was controlled via a thermostat (Phoenix II, Thermo Fisher Scientific, Waltham, MA, USA together with Haake C25P, Thermo Fisher Scientific, Waltham, MA, USA), and the sample was equilibrated for 25 min inside the decaline-filled refractive index matching bath. For each temperature, 5 consecutive measurements were performed. The obtained mean relaxation rates $\Gamma$ of the $g^1\left(t\right)$ functions were converted to the hydrodynamic radius by
$R_h=\frac{k_{B}T}{6\pi \eta \frac{\Gamma }{q^2}}.$ Here, $k_B$ is the Boltzmann constant, $\eta$ the solvent viscosity (water), T the temperature in Kelvin, and $q=\frac{4\pi n}{\lambda }sin\frac{\theta }{2}$ the magnitude of the scattering vector. n is the refractive index of the solvent.

The surface tension difference of alginate suspension and emulsion were measured at 20 °C with a digital tensiometer (DCA, digital tensiometer, Gibertini, Elettronica srl., Novate Milanese, Milano, Italy) using the Wilhelmy plate device. Edible coatings were characterized for rheological response to oscillatory mechanical tests using a modular rheometer (Haake MARS III-Thermo Scientific, Karlsruhe, Germany) equipped with a 60 mm parallel plate geometry probe at a gap distance of 0.07 mm to mimic the thickness of the coating applied on the banana fruit surface. The temperature, controlled by a cooling and heating system (Phoenix II, Thermo Scientific, Karlsruhe, Germany), combined with a Peltier system, was set at 20 °C. For studying the behavior of the coating made of alginate emulsion, the dispersion was sprayed with the airbrush on the lower plate, and for crosslinked hydrogel a second step of CaCl₂ spraying followed. Amplitude sweep tests were carried out in control stress mode by varying the applied stress according to the sample differences, and keeping the frequency fixed at 1 Hz. Frequency sweep tests were made in a frequency range between 0.1 and 10 Hz and by applying a stress taken from the linear viscoelastic region. The stress applied for alginate emulsion and for crosslinked hydrogel were of 0.05 and 0.01 Pa, respectively.