Genesys 10 s uv vis spectrometer

The antioxidant activity was evaluated in vitro by DPPH scavenging method. A total of 1 g of soursop fruit tea was weighed, homogenized with 50 mL of ethanol, and filtered to obtain the extract. The extract (0.5 mL) was placed in a test tube and added with 1.5 mL of DPPH. The sample was incubated in darkness for 30 min before optical absorbance measurement using Thermo Scientific GENESYS 10S UV–Vis Spectrometer at a wavelength of 517 nm (Brand‐Williams et al., 1995 (link); Tran et al., 2023 (link)).
The antioxidant activity was evaluated in vitro by the ABTS scavenging method as previously described by Nguyen et al. (2023 (link)). A total of 1 g of soursop fruit tea was weighed, homogenized with 50 mL of ethanol, and filtered to obtain the extract. The extract (0.5 mL) was mixed with 1.5 mL of ABTS in a test tube. The sample was incubated in the dark for 30 min before measurement by using Thermo Scientific™ GENESYS 10S UV–Vis Spectrometer at a wavelength of 734 nm.

Total polyphenol content of soursop fruit tea extract was determined by the Folin–Ciocalteu colorimetric method, using gallic acid as a standard and previously described by Gyesi et al. (2019 (link)) and Dao et al. (2021 (link)). A total of 1 g of soursop fruit tea was weighed, homogenized with 50 mL of ethanol, and filtered to obtain the extract. The extract (0.1 mL) was placed in a dark‐colored test tube and added with 0.5 mL of FCR 10%, and 0.4 mL 7.5% Na₂SO₃. The sample was incubated in the dark for 1 h before absorbance measurement at the wavelength of 765 nm using GENESYS™ 10S UV–Vis spectrometer (Thermo Scientific, USA). TPC is expressed in milligrams of Gallic acid equivalent (GAE) and calculated by Equation (5). $$\mathrm{TPC}=\frac{C_x\times n\times V\times 100}{m\times \left(100-X\right)}\times {10}^{-3},$$ where Cx is the concentration of gallic acid determined from the standard curve (μg/mL): Cx=61.0676×A+1.8598, R = 0.9991; n is the dilution from the original extract; V is the volume of the original extract (mL); X is the sample moisture (%) and m is the weight of sample (g).

The obtained supernatants were carefully removed from the precipitated NPs, then diluted to a suitable range with purified water and the absorption was measured by using a UV spectrometer (ThermoScientific-Genesys 10 S UV-Vis Spectrometer, USA) at lambda max 281 nm. Based on the absorbance, the concentration of unprecipitated NP enzymes was used to calculate precipitation efficiency.
The obtained supernatants were carefully separated from the encapsulated NPs and absorption was measured at 281 nm for each sample based on a pre-recorded calibration line. The concentration of free enzyme NPs was measured for all samples, from which encapsulation efficiency was determined. Encapsulation efficiency (EE%) resulting from the adsorption of alginate on the LYS composite was calculated according to the following equation:
$$EE\mathrm{\%}=\frac{\left(totalamountofLYS\right(mg)-amountofLYZinthesupernatantsol.(mg\left)\right)}{totalamountofLYS\left(mg\right)}*100$$