Role of infrared-assisted extraction of antioxidant phytochemicals in enhancing antimicrobial activity of Phaeodactylum tricornutum

Abstract

Microalgae are a sustainable source of highly bioactive and nutritious biomolecules such as polyphenols, and carotenoids. The efficiency of a novel infrared (IR) technology in terms of optimization of phytochemical (phenolic compounds, chlorophylls and carotenoids) recovery from P. tricornutum was studied using Response Surface Methodology (RSM). Optimized antioxidant activity (870 ± 22 μg TE/mL) and phenolic compound concentration (562 ± 7 mg GAE/100 g DM) were obtained using IR at 33 °C for 12 min at pH 7. In addition, chlorophyll A (26.54 ± 2.78 mg/100 g DM) and carotenoids (9.61 ± 0.40 mg/100 g DM) were recovered at the simultaneous optimal IR conditions: 56 °C, 36 min, pH 9.5. Compared to conventional aqueous extraction, IR enhanced by 10.06% the recovery of phenolic compounds and ameliorated their biological activities by 36.24% for DPPH, 17.24% for CUPRAC, 14.50% for TEAC, and 4.60% for FRAP. Finally, IR bioactive extracts also exhibited antibacterial effects against S. aureus. In conclusion, the richness of P. tricornutum in phytochemicals makes it a valuable alternative food source. IR technology proved to be an efficient method for the recovery of high-added value compounds from microalgae. Antioxidant and pigment-rich microalgae extracts can be used as dietary supplements.