2.5.6. Antioxidant Activity

The 2,2-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid (ABTS) assay was used to measure the antioxidant activity of the biocomposites. A radical solution (7 mM ABTS and 2.45 mM potassium persulphate) was prepared and left in dark during 14–16 h before testing. The radical solution was adjusted to an absorbance of 0.70 ± 0.02 at 734 nm diluting with ethanol. A specimen of 0.5–1 cm<sup>2</sup> of the biocomposites was added to a 4 mL of radical solution and the absorbance of the solution was measured at 734 nm using ethanol as blank. The absorbance was measured after 6 min. The antioxidant activity was determined according to the following equation [45]:

$$AOP\left(\%\right) = \frac{A\_{734,ABTS6'} - A\_{734,\text{sample}}}{A\_{734,ABTS6'}} \times 100\tag{1}$$

where A734,ABTS6' is the absorbance at 734 nm of the radical solution after 6 min, A734,sample6' the absorbance at 734 nm of the sample after 6 min, and A734,ABTS0' the absorbance at 734 nm of the radical solution before the 6 min. Because the radical scavenging activity was performed in the surface of the biocomposites, the antioxidant activity was related to the surface exposed to the radical solution, expressed as antioxidant potential, (AOP%/cm2).

#### **3. Results and Discussion**
