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

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).

Automated summary

This study aimed to evaluate the recovery of high added-value compounds from Phaedoactylum tricornutum assisted by ultrasound, and optimized the extraction of proteins, carbohydrates, pigments and antioxidant compounds using response surface methodology. Results showed that carbohydrate extraction was influenced by temperature, while carotenoid extraction was mainly affected by extraction time. Total polyphenols were significantly affected by extraction time. Antioxidant capacity was modulated by extraction time for ABTS assay, and by temperature and extraction time for ORAC assay. Optimal conditions for maximum extraction of nutrients, bioactive compounds and antioxidant capacity were found to be 30 min, 50°C and pH 8.5.