## 3 Results and Discussion
### Bioactivity Characterisation  
#### 3.8.1 Total Phenolic Content and Antioxidant Activity of Free and Bound Phenolics  
The TPC and antioxidant activity (DPPH, ABTS and ORAC) of crude olive pomace, liquid and pulp fraction samples are presented in Figure 3. Total TPC resulted from the sum of the free phenolic compounds with the bound phenolic compounds. TPC in the crude olive pomace samples was of  
Figure 2: FTIR spectra of the liquid-rich fraction (L-OP) and pulp-rich fraction (P-OP) produced after the wet and dry fractionation process of crude olive pomace (C-OP). Abbreviations: C-OP—crude olive pomace, L-OP—liquid-rich fraction, P-OP—pulp-rich fraction. 22.73-24.51 mg GAE/g DW in crude olive pomace without significant differences between each other (\(p>0.05\)) regarding TPC from free and bound phenolic compounds. Different TPC results were reported in previous works for crude olive pomace: higher [38] and lower values [20], mainly due to the differences between olive cultivars and oil extraction conditions. Figure 3: Content of total, free and bound phenolic compounds and antioxidant activity using DPPH, ABTS and ORAC methods from crude olive pomace (C-OP), the liquid-rich fraction (L-OP) and pulp-rich fraction from olive pomace (P-OP). Data were expressed as mean \(\pm\) SD (n = 3). The different superscripts in the same column were significantly different (\(p<0.05\)). Abbreviations: OM 1—olive mill 1, OM 2—olive mill 2, C-OP—crude olive pomace, L-OP—liquid-rich fraction, P-OP—pulp-rich fraction. GAE—Gallic acid equivalents, TE—Trolox equivalents. Liquid fraction (21.21-22.67 mg GAE/g DW) and crude olive pomace exhibited similar values of TPC regarding free phenolic extracts, and pulp fraction (8.32-14.86 mg GAE/g DW) revealed significantly lower values (\(p<0.05\)). On the other hand, TPC of bound phenolic extracts from pulp fraction (2.78-5.13 mg GAE/g DW) was similar or higher than in crude olive pomace samples (3.20-3.62 mg GAE/g DW). However, as expected, higher recovery of phenolic compounds was achieved in liquid rather than in pulp fraction. Antioxidant activity of crude olive pomace and edible fractions (liquid and pulp fraction) were evaluated using three different methods (DPPH, ABTS and ORAC), due to the absence of a single antioxidant determination methodology able to reflect the total antioxidant activity of a sample. The model of scavenging stable radicals, DPPH, is widely used to evaluate antioxidant capacities of natural products, including olive oil samples [52]. The DPPH method showed that the proton-removal activity of free phenolic compounds from the liquid fraction (76.03-106.03 \(\upmu\)M TE/g DW) was higher than pulp fraction (41.05-79.20 \(\upmu\)M TE/g DW) and analogous to crude olive pomace (79.94-103.15 \(\upmu\)M TE/g DW). ABTS showed the same tendency as DPPH, where free phenolic compounds' extract of the liquid fraction showed higher values of antioxidant activity and similar to crude olive pomace. Nonetheless, the bound phenolic extracts of the pulp fraction had the double capacity (21.25-26.98 \(\upmu\)M TE/g DW) to inhibit the free radicals when compared to the liquid fraction (12.34-13.34 \(\upmu\)M TE/g DW) (\(p<0.05\)). When comparing ABTS with DPPH, ABTS had higher values, which could be related to the use of methanol in both methods. Water is commonly used as a solvent in ABTS, and its substitution by methanol allows to improve the evaluation of the total antioxidant activity of complex samples (aqueous and organic compounds) [33]. In ORAC, the liquid fraction (1546.93-1585.46 \(\upmu\)M TE/g DW) also showed the highest antioxidant activity value compared to the pulp fraction (454.74-502.80 \(\upmu\)M TE/g DW) or crude olive pomace (641.05-734.81 \(\upmu\)M TE/g DW) (\(p<0.05\)). The ORAC values were much higher than the values obtained by DPPH and ABTS. Similar differences were reported in antioxidant activity assays of olives [53] and olive pomace [38].