The application of pulsed electric fields (PEF) is an innovative extraction technology promoting cell membrane electroporation, thus allowing for an efficient recovery, from an energy point of view, of antioxidant compounds (chlorophylls, carotenoids, total phenolic compounds, etc.) from microalgae. Due to its selectivity and high extraction yield, the effects of PEF pre-treatment (3 kV/cm, 100 kJ/kg) combined with supplementary extraction at different times (5–180 min) and with different solvents (ethanol (EtOH)/H₂O, 50:50, v/v; dimethyl sulfoxide (DMSO)/H₂O, 50:50, v/v) were evaluated in order to obtain the optimal conditions for the extraction of different antioxidant compounds and pigments. In addition, the results obtained were compared with those of a conventional treatment (without PEF pre-treatment but with constant shaking). After carrying out the different experiments, the best extraction conditions to recover the different compounds were obtained after applying PEF pre-treatment combined with the binary mixture EtOH/H₂O, 50:50, v/v, for 60–120 min. PEF extraction was more efficient throughout the study, especially at short extraction times (5–15 min). In this sense, recovery of 55–60%, 85–90%, and 60–70% was obtained for chlorophylls, carotenoids, and total phenolic compounds, respectively, compared to the maximum total extracted amount. These results show that PEF improves the extraction yield of antioxidant bioactive compounds from microalgae and is a promising technology due to its profitability and environmental sustainability.

Spirulina (Arthrospira platensis) has been consumed by humans since ancient times. It is rich in high added-value compounds such as chlorophylls, carotenoids and polyphenols. Pulsed electric fields (PEF) is an innovative non-thermal technique that improves the extraction of bioactive compounds from diverse sources. PEF pre-treatment (3 kV/cm, 100 kJ/kg) combined with supplementary extraction with binary solvents at different times was evaluated to obtain the optimal conditions for extraction. In addition, the results obtained were compared with conventional treatment (without PEF pre-treatment and constant shaking) and different strains of Spirulina from diverse geographical locations. The optimal extraction conditions for recovering the bioactive compounds were obtained after applying PEF treatment combined with the binary mixture EtOH/H₂O for 180 min. The recovery of total phenolic content (TPC) (19.76 ± 0.50 mg/g DM (dry matter) and carotenoids (0.50 ± 0.01 mg/g DM) was more efficient in the Spirulina from Spain. On the other hand, there was a higher recovery of chlorophylls in the Spirulina from China. The highest extraction of total antioxidant compounds was in Spirulina from Costa Rica. These results show that PEF, solvents and the condition of growing affect the extraction of antioxidant bioactive compounds from Spirulina. The combination of PEF and EtOH/H₂O is a promising technology due to its environmental sustainability.

Fish side streams represent between 20–80% of the weight of fish, and their disposal represents an environmental and economic problem. These side streams contain proteins and antioxidant compounds that give them added value. In order to valorise these side streams, an extraction assisted by pulsed electric fields (PEF) was carried out to obtain proteins and compounds with antioxidant activity. An extraction for the same time but without PEF pre-treatment was used as a control. The side streams used were head, skin, viscera and backbone from sea bass. The antioxidant capacity was measured by two complementary methods, TEAC and ORAC. The results showed that in the case of head and skin, treatment with PEF notably improved protein extraction by 37.7 and 37.8%, respectively. However, for viscera, the best values were achieved with the control extraction. Finally, backbone did not show significant differences in protein recovery between PEF-assisted extraction and control extraction. Regarding antioxidant capacity, the results followed the same trend as for proteins. For head and skin, the pre-treatment with PEF increased the extraction of antioxidant compounds, improving the TEAC values by 21.74 and 29.11%, respectively. On the other hand, ORAC results increased 22.11% for head extracts and 40.93% for skin extracts. In the extracts obtained from the viscera, the TEAC and ORAC values were better in the control sample, being 21.43% and 24.82% higher, respectively. The antioxidant compounds present in the samples may be bioactive peptides, but a more exhaustive analysis using chromatographic techniques would be necessary to complete the information. Therefore, it has been seen that PEF-assisted extraction can be a good strategy to increase the recovery of proteins and antioxidant compounds from fish side streams such as head or skin, but not for viscera and backbone.

Currently, there is a growing nutritional interest in microalgae because they are a good source of nutrients and bioactive compounds. These bioactive compounds include polyphenols, which are known to be beneficial to health due to their antioxidant capacity. However, their extraction by conventional methods requires time and uses organic solvents, which are harmful to the environment. To reduce both time and environmental impact, the use of pulsed electric fields technology as a pre-treatment prior to extraction by stirring has been studied. For this purpose, a treatment of 100 kJ/kg at 3 kV/cm was applied to a suspension of 2% spirulina in water. Afterwards, an extraction was carried out using ethanol (EtOH) 50% or dimethyl sulfoxide (DMSO) 50% in water (v/v) for 3 h. In order to evaluate both the polyphenol extraction and the antioxidant capacity, a kinetic curve for each was established at different extraction times with the different solvents. It was observed that pre-treatment with PEF had a significant (p < 0.05) positive effect on the extraction at all times with respect to the conventional treatment. The greatest differences were observed in the first 5–15 min of the extraction. The highest antioxidant capacity measured by ORAC and TEAC was obtained using EtOH as solvent. When DMSO was used, PEF pre-treatment allowed a higher recovery of polyphenols after 5 min (12.53 ± 0.31 mg gallic acid equivalents (GAE)/g dry weight) than the control sample after 180 min (4.84 ± 0.48 mg/g). For both solvents, the highest value of total phenolic compounds (TPC) was obtained after 120 min of extraction. Finally, PEF increased the extraction of polyphenols by 408% using EtOH 50% as solvent. It can be concluded that PEF technology increases the extraction of polyphenols from microalgae, reducing the process time and the consumption of organic solvents.

Pulsed electric field (PEF) is an innovative technology that allows the creation of pores in the cell membrane through the application of an electric field. Among its main advantages, the increase in the extraction performance of intracellular compounds stands out. In order to study this effect on pigment recovery, a PEF-assisted extraction was performed. For that purpose, a PEF treatment at 3 kV/cm and 100 kJ/kg was applied to a 2% (p/v) suspension of the Arthrospira platensis microalgae, also known as spirulina. After pre-treatment with PEF, the suspension was stirred for 3 h, taking samples at different times. This extraction was compared with a control extraction, which consisted of stirring for 3 h without PEF pre-treatment. Furthermore, the influence of the solvent was evaluated in each case. Therefore, the extraction yield obtained using ethanol 50% (v/v) and DMSO 50% (v/v) was compared. The best results were obtained using 50% (v/v) ethanol as a solvent. In addition, a greater extraction of pigments was observed in the samples pre-treated with PEF. This was especially noticeable at lower extraction times. In conclusion, these results show that PEF is a promising technology for pigment extraction as it is environmentally friendly while improving the profitability of the process.