Exploring Ultrasound, Microwave and Ultrasound–Microwave Assisted Extraction Technologies to Increase the Extraction of Bioactive Compounds and Antioxidants from Brown Macroalgae

Abstract

This study aims to determine the influence of (1) ultrasound-assisted extraction (UAE), (2) microwave-assisted extraction (MAE) and (3) a combination of ultrasound–microwave-assisted extraction (UMAE) on the yields of fucose-sulphated polysaccharides (FSPs), total soluble carbohydrates and antioxidants extracted from A. nodosum. Scanning electron microscopy (SEM) was used to evaluate the influence of the extraction technologies on the surface of macroalgae while principal component analysis was used to assess the influence of the extraction forces on the yields of compounds. UMAE generated higher yields of compounds compared to UAE and MAE methods separately. The maximum yields of compounds achieved using UMAE were: FSPs (3533.75 ± 55.81 mg fucose/100 g dried macroalgae (dm)), total soluble carbohydrates (10408.72 ± 229.11 mg glucose equivalents/100 g dm) and phenolic compounds (2605.89 ± 192.97 mg gallic acid equivalents/100 g dm). The antioxidant properties of the extracts showed no clear trend or extreme improvements by using UAE, MAE or UMAE. The macroalgal cells were strongly altered by the application of MAE and UMAE, as revealed by the SEM images. Further research will be needed to understand the combined effect of sono-generated and microwave-induced modifications on macroalgae that will allow us to tailor the forces of extraction to target specific molecules.

Optimisation of Ultrasound Frequency, Extraction Time and Solvent for the Recovery of Polyphenols, Phlorotannins and Associated Antioxidant Activity from Brown Seaweeds

“…The cell surfaces of treated samples exhibit an increased porosity that facilitated the extraction of higher yields of TPC and TPhC compared to control samples (Table 1). Previously, Rodriguez-Jasso et al [22] and Garcia-Vaquero et al [23] reported similar findings when evaluating the efficiency of MAE, UAE and UMAE (ultrasound-microwave assisted extraction) to generate extracts from F. vesiculosus and A. nodosum seaweed.…”

“…Scanning Electron Microscopy (SEM) was used to investigate the effect of ultrasound on F. vesiculosus surface characteristics. Dried seaweed samples and pellets from the extraction conditions achieving high extraction yields (35 kHz, 50% ethanol, 30 min) and control (no ultrasound, 50% ethanol, 30 min) were collected and prepared as described by Garcia-Vaquero et al [23]. The images were recorded using a SEM Regulus 8230 (Hitachi Ltd., Tokyo, Japan).…”

Macroalgae—A Sustainable Source of Chemical Compounds with Biological Activities

“…Worth mentioning, among them are phytopigments (xanthophylls and carotenoids), polyunsaturated fatty acids (PUFAs) comprising docosahexaenoic acid (DHA), phenolic compounds, tannins, peptides, lipids, enzymes, vitamins, carbohydrates, terpenoids, and others. Thus, algae are a viable and economical biomass source of valuable compounds with potential applications in the nutraceutical, pharmaceutical, chemical, food, and cosmetic industries due to their biologically active and regenerative properties [ 2 , 3 , 4 , 5 , 6 ].…”

Matrix solid-phase dispersion as a greener alternative to obtain bioactive extracts from Haematococcus pluvialis. Characterization by UHPLC-QToF

“…10 Recently, accelerated and compressed uid-based extraction techniques such as Accelerated Solvent Extraction (ASE), Ultrasound-Microwave Assisted Extraction (UMAE), Pressurized Liquid Extraction (PLE) and Supercritical Antisolvent Fractionation (SAF), have gained considerable interest in the extraction of bioactive substances from algae. [11][12][13] Many of these techniques are efficient on a small scale, not being widely applied in the industrial eld due to their high energy requirements. 14 In addition, there is currently a limited understanding of the key variables that affect the performance of these extraction processes.…”