Ultrasound Extraction Mediated Recovery of Nutrients and Antioxidant Bioactive Compounds from Phaeodactylum tricornutum Microalgae

Abstract

In recent years, a growing interest has been shown in the use of microalgae due to their interesting nutritional and bioactive profiles. Green innovative processing technologies such as ultrasound-assisted extraction (UAE) avoid the use of toxic solvents and high temperatures, being a sustainable alternative in comparison with traditional extraction methods. The present study aims to evaluate the recovery of high added-value compounds from Phaedoactylum tricornutum assisted by ultrasound. To optimize the UAE of proteins, carbohydrates, pigments and antioxidant compounds, a response surface methodology was used. Carbohydrate extraction was positively affected by the temperature. However, for the extraction of carotenoids, the most influential factor was the extraction time. The total polyphenols were only significantly affected by the extraction time. Finally, the antioxidant capacity, measured by 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), was strongly modulated by the extraction time, while for the oxygen radical antioxidant capacity (ORAC) assay, the most important parameter was the temperature, followed by the extraction time. The optimal conditions for the maximum extraction of nutrients, bioactive compounds and antioxidant capacity were 30 min, 50 ºC and a pH of 8.5. Finally, it has been seen that with these conditions, the extraction of fucoxanthin is allowed, although no differences were found between an ultrasound-assisted extraction and a shaking extraction (control).

Total Phenolic Content, Biomass Composition, and Antioxidant Activity of Selected Marine Microalgal Species with Potential as Aquaculture Feed

“…Apart from the differences in the units of available data, there is also a variation in the results of different authors, with some reporting a correlation of phenolic content with antioxidant capacity [ 20 , 47 ] while others do not [ 48 , 49 ]. Variation in the phenolic content measured by Folin–Ciocalteu in the literature might stem from actual differences in the phenolic content of different species and the effect of different growth conditions; however, it might also be related to the choice of solvents, extraction time [ 50 ], and temperature. Regarding the choice of solvent, phenolic compounds are often extracted from the microalgal cells using only methanol.…”

Extraction of Antioxidant Compounds and Pigments from Spirulina (Arthrospira platensis) Assisted by Pulsed Electric Fields and the Binary Mixture of Organic Solvents and Water

“…The higher ORAC values are due to other 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].…”

“…The method used was previously described by Khawli et al [34]. This assay measures the oxidative degradation of a fluorescent molecule such as fluorescein (Sigma-Aldrich, St. Louis, MO, USA) after the addition of a free radical generator such as 2,2 -azobis(2-aminodinopropane) dihydrochloride (AAPH).…”

Effect of Salt Stress on the Phenolic Compounds, Antioxidant Capacity, Microbial Load, and <em>In Vitro </em>Bioaccessibility of Two Microalgae Species (<em>Phaeodactylum tricornutum </em>and <em>Spirulina platensis</em>)

“…A positive and moderate correlation (r = 0.67) was found for the P. tricornutum samples while a negative and strong (r = −0.86) correlation was observed for the S. platensis samples between the salt concentration and ABTS in the present study. It was reported in a previous study that the maximum antioxidant capacity of the P. tricornutum samples evaluated using the ABTS method was found as 758.28 M TE and this value was obtained through extraction for 28.36 min under optimal conditions of 20 • C temperature and 5.5 pH [26]. Goiris et al [5] reported that the ABTS capacity of P. tricornutum ranged between 4.55 and 48.90 µmol Trolox/g DW.…”