## 3 Results and Discussion
### Pulsed Electric Fields (PEF)-Assisted Extraction  
#### 3.2.1 Ethanol/Water  
Figure 6 shows the results obtained after applying both treatments (conventional and PEF) using the mixture EtOH/H\({}_{2}\)O. After performing a two-way ANOVA analysis (time and treatment), it was observed that both the extraction time and the use of the PEF pre-treatment had a significant effect (\(p<0.05\)) on the extraction of chlorophylls, carotenoids, (Figure 6a), and total phenolic compounds (Figure 6b). This effect is due to the electroporation produced by the PEF, which facilitates the extraction of these compounds more efficiently and with less agitation time.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **TPC** & **TEAC** & **ORAC** & **Chlorophyll a** & **Chlorophyll b** & **Carotenoids** \\ \hline TPC & & 0.7114 & 0.0301 & 0.7016 & 0.6827 & 0.5727 \\  & & (36) & (36) & (36) & (36) & (36) \\  & & 0.0000 & 0.8618 & 0.0000 & 0.0000 & 0.0003 \\ \hline TEAC & 0.7114 & & \(-\)0.3054 & 0.7986 & 0.8419 & 0.6306 \\  & (36) & & (36) & (36) & (36) & (36) \\  & 0.0000 & & 0.0701 & 0.0000 & 0.0000 & 0.0000 \\ \hline ORAC & 0.0301 & \(-\)0.3054 & & 0.1415 & 0.1164 & 0.3586 \\  & (36) & (36) & & (36) & (36) & (36) \\  & 0.8618 & 0.0701 & & 0.4103 & 0.4991 & 0.0317 \\ \hline Chlorophyll a & 0.7016 & 0.7986 & 0.1415 & & 0.9511 & 0.8735 \\  & (36) & (36) & (36) & & (36) & (36) \\  & 0.0000 & 0.0000 & 0.4103 & & 0.0000 & 0.0000 \\ \hline Chlorophyll b & 0.6827 & 0.8419 & 0.1164 & 0.9511 & & 0.9169 \\  & (36) & (36) & (36) & (36) & & (36) \\  & 0.0000 & 0.0000 & 0.4991 & 0.0000 & & 0.0000 \\ \hline Carotenoids & 0.5727 & 0.6306 & 0.3586 & 0.8735 & 0.9169 & \\  & (36) & (36) & (36) & (36) & (36) & \\  & 0.0003 & 0.0000 & 0.0317 & 0.0000 & 0.0000 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Correlation between antioxidant compounds and total antioxidant capacity (TEAC and ORAC).  
Figure 6: _Cont._  
It should be noted that no significant differences were observed regarding the maximum carotenoid content obtained after applying PEF pre-treatment for 60 min (0.50 \(\pm\) 0.01 mg/g DM) or after conventional treatment without PEF for 180 min (0.50 \(\pm\) 0.01 mg/g DM), which showed that PEF is an effective tool to reduce carotenoid extraction time, being 3 times faster than conventional extraction. A similar effect was observed for chlorophyll a: We obtained similar values after applying PEF and supplementary extraction for 120 min (0.60 \(\pm\) 0.01 mg/g DM) as those obtained with conventional treatment for 180 min (0.57 \(\pm\) 0.04 mg/g DM), observing a reduction of 60 min in the time to obtain the maximum chlorophyll a content. Moreover, PEF pre-treatment increased the extraction of chlorophyll b throughout all the extraction times compared to that of the control sample.  
After analysing the statistical data of the TPC values, it was found that the pre-treatment with PEF also had a very positive effect on the extraction, obtaining significant differences (\(p<0.05\)) compared to those of the conventional treatment, independently of the extraction time. Moreover, it was also observed that after PEF extraction, the TPC values were 2-3-fold higher. For example, after 180 min of conventional extraction, TPC values of 4.84 \(\pm\) 0.48 mg GAE/g DM were obtained, while the value obtained at the same time after PEF pre-treatment was 19.75 \(\pm\) 0.50 mg GAE/g DM, representing a 75% increase. The increase in chlorophylls, carotenoids, total phenolic compounds, and TAC content obtained after PEF application compared to those of conventional extraction is in agreement with the results obtained by other authors after similar experiments with the microalgae _Nannochloropsis_ spp. [13].