Evolution 201 220 uv vis thermo scientific

The antioxidant activity of BC and BC-CH films (n = 3) was determined by measuring the free radical scavenging activity using the ABTS (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) method [31 (link),32 (link)]. For analysis, an aqueous solution of ABTS (7 mM) and potassium persulfate (140 mM) was prepared and kept in the dark for a period of 16 h; subsequently, the absorbance of the solution was measured at 734 nm using a spectrophotometer (Evolution™ 201/220 UV-Vis Thermo Scientific™, Waltham, Ma, USA). Later, the solution was diluted with distilled water to obtain an absorbance value between 0.7 and 1.00 at this wavelength. Next, the 25 µL of the methanolic extract was mixed with 1 mL of ABTS reagent and kept in the dark for 45 min. Changes in the absorbance were measured, and antioxidant activity was expressed as % ABTS radical scavenging activity using the following equation: ABTS radical scavenging activity (%) = (absorbance of ABTS solution − absorbance of sample/absorbance of ABTS solution) × 100 [32 (link)].

The total phenolic content of all developed films (n = 3) was determined by the Folin-Ciocalteu procedure [27 ] and expressed as mg gallic acid equivalents (GAE)/g of dry weight. The concentration was calculated independently in triplicates (n = 3). The determination was carried out with 250 µL of the methanolic extract, 800 µL of water, 50 µL of Folin-Ciocalteu reagent (1 N), and 800 µL of Na₂CO₃ at 7.5%. Subsequently, they were kept for 30 min in the dark, and the reading was performed in a spectrophotometer (Evolution™ 201/220 UV-Vis Thermo Scientific™, Waltham, MA, USA) at 750 nm.

The antioxidant activity of BC and BC-CH films (n = 3) was evaluated using tests for scavenging of free radicals of DPPH (2,2-diphenyl-1-picrylhydrazyl) following the methods of Blois [28 (link)], Siripatrawan, and Harte [29 (link)], and Wang et al. [20 (link)], with some modifications. From the methanolic extract, 0.050 mL was taken and mixed with 1 mL of the DPPH solution. The mixture was then incubated at room temperature for 30 min, and the absorbance at 517 nm was determined using a spectrophotometer (Evolution™ 201/220 UV-Vis Thermo Scientific™, Waltham, MA, USA) [30 (link)]. Changes in the absorbance were measured, and antioxidant activity was expressed as % DPPH radical scavenging activity using the following equation: DPPH radical scavenging activity (%) = (absorbance of DPPH solution − absorbance of sample/absorbance of DPPH solution) × 100 [19 (link),20 (link)].