## 3 Results and Discussion
### Conventional Extraction
#### 3.1.2 Total Phenolic Compounds (TPC) and Total Antioxidant Capacity (TAC)  
Figure 4 shows the results obtained for total phenolic compounds (TPC) and total antioxidant capacity (TAC) determined by TEAC and ORAC. After performing a 2-factor analysis of variance (ANOVA) (time and solvent), it was observed that both time and solvent had a significant effect (\(p<0.05\)) on the extraction of phenolic compounds. ORAC values ranged from 295.87 \(\pm\) 19.01 to 393.24 \(\pm\) 15.28 \(\upmu\)mol TE/g DM after using EtOH/H\({}_{2}\)O and from 72.45 \(\pm\) 5.95 to 155.95 \(\pm\) 10.78 \(\upmu\)mol TE/g DM when the mixture DMSO/H\({}_{2}\)O was used. In addition, a greater effect on the extraction of antioxidant compounds was observed at 30 and 180 min, respectively. On the other hand, the TEAC values ranged from 4.52 \(\pm\) 0.02 to 19.05 \(\pm\) 1.25 \(\upmu\)mol TE/g DM after using the EtOH/H\({}_{2}\)O mixture and from 9.19 \(\pm\) 0.62 to 16.19 \(\pm\) 1.37 \(\upmu\)mol TE/g DM with the DMSO/H\({}_{2}\)O mixture. The maximum value for the TEAC assay (19.05 \(\upmu\)mol TE/g DW) was obtained after 180 min extraction and using EtOH 50% as the solvent. The highest ORAC value was also obtained after using EtOH, but after 30 min of extraction (393.24 \(\upmu\)mol TE/g DW). Regarding DMSO, the best values for TEAC and ORAC were obtained at 60 min (16.19 \(\upmu\)mol TE/g DW) and 15 min (155.95 \(\upmu\)mol TE/g DW), respectively. The higher ORAC values are due to other  
Figure 4: Total phenolic compounds, TEAC and ORAC. Conventional extraction (5–180 min) using two binary mixtures (EOH or DMSO in 50% deionised water). Different lower-case letters in the same parameter and solvent indicate statistical differences as a function of extraction time. Different capital letters in the same parameter and time indicate statistical differences as a function of solvent. antioxidant compounds not measured in this study, especially fat-soluble compounds such as vitamin E that may have an impact on the antioxidant capacity [38; 39; 40]. Moreover, ORAC sensitivity for other antioxidant compounds should also be taken into account [34]. In the determination of total phenolic compounds (TPC), concentrations between 3.64 \(\pm\) 0.07 and 6.04 \(\pm\) 0.28 mg GAE/g DM were obtained for the EtOH/H\({}_{2}\)O extraction and between 1.91 \(\pm\) 0.07 and 5.921 \(\pm\) 0.175 mg GAE/g DM for the DMSO/H\({}_{2}\)O extraction and 5.921 \(\pm\) 0.175 mg GAE/g DM in the extraction with DMSO/H\({}_{2}\)O: For both solvents, the highest values were obtained at 120 min, the phenolic content at that time was similar to that obtained by [PERSON] et al. [41] for spirulina. Regarding the mean values of TAC (TEAC + ORAC), it is worth noting that the values obtained with DMSO/H\({}_{2}\)O are relatively lower compared to those of the EtOH/H\({}_{2}\)O mixture, independent of the extraction time (Figure 5). This may be due to a lower extraction of chlorophylls, carotenoids, and phenolic compounds, as seen above, suggesting a clear contribution of these compounds to TAC. This same correlation has been previously observed by other authors after evaluating the use of these solvents for the extraction of these compounds from the microalgae _Nannochloropsis_[13]. To evaluate the possible correlations between the different antioxidant compounds (chlorophyll a, chlorophyll b, carotenoids, and total phenolic compounds) and the determination methods used for total antioxidant capacity (TEAC and ORAC), a Pearson's test was performed for 36 samples (Table 1). The main correlations were observed between TEAC and carotenoids (R = 0.9094, \(p\) < 0.05), chlorophyll a (R = 0.7986, \(p\) < 0.05), chlorophyll b (R = 0.8419, \(p\) < 0.05), and total phenolic compounds (R = 0.7114, \(p\) < 0.05), obtaining moderate to high positive correlation coefficients.