Extraction and characterization of protein from Irish brown seaweed Ascophyllum nodosum.

This study investigates traditional and non-conventional methods of extraction of protein from Irish brown seaweed A. nodosum. Acid, alkali, combined acid-alkali with and without ultrasound pretreatment were investigated for extraction of protein from A. nodosum. Molecular weight of protein was determined using high performance size exclusion chromatography and amino acid profiling was carried out using an amino acid analyzer. Combination of first acid and then alkali extraction was found to be the most efficient method of extraction among all methods investigated (59% of recovery); followed by single step of alkali extraction assisted with ultrasound (68.4µm) which was able to extract 57% of total protein. Alkaline extraction was shown to yield the best protein/algae liquefaction ratio (1.28). This can be attributed to the release of polysaccharide complexes first by acid and then solubilization of proteins by alkali solvent. The molecular weight of extracted protein was found to be relatively low, in the range of 2-4kDa average MW. The alkali method of extraction was found to be optimum for extraction of amino acids from A. nodosum.

Power ultrasound as a pretreatment to convective drying of mulberry (Morus alba L.) leaves: Impact on drying kinetics and selected quality properties.

The effect of ultrasound pretreatment prior to convective drying on drying kinetics and selected quality properties of mulberry leaves was investigated in this study. Ultrasound pretreatment was carried out at 25.2-117.6 W/L for 5-15 min in a continuous mode. After sonication, mulberry leaves were dried in a hot-air convective dryer at 60 °C. The results revealed that ultrasound pretreatment not only affected the weight of mulberry leaves, it also enhanced the convective drying kinetics and reduced total energy consumption. The drying kinetics was modeled using a diffusion model considering external resistance and effective diffusion coefficient De and mass transfer coefficient hm were identified. Both De and hm during convective drying increased with the increase of acoustic energy density (AED) and ultrasound duration. However, De and hm increased slowly at high AED levels. Furthermore, ultrasound pretreatment had a more profound influence on internal mass transfer resistance than on external mass transfer resistance during drying according to Sherwood numbers. Regarding the quality properties, the color, antioxidant activity and contents of several bioactive compounds of dried mulberry leaves pretreated by ultrasound at 63.0 W/L for 10 min were similar to that of mulberry leaves without any pretreatments. Overall, ultrasound pretreatment is effective to shorten the subsequent drying time of mulberry leaves without damaging the quality of final product.

Laminarin from Irish Brown Seaweeds Ascophyllum nodosum and Laminaria hyperborea: Ultrasound Assisted Extraction, Characterization and Bioactivity.

Ultrasound assisted extraction (UAE), purification, characterization and antioxidant activity of laminarin from Irish brown seaweeds Ascophyllum nodosum and Laminarina hyperborea were investigated. UAE was carried out using 60% ultrasonic power amplitude and 0.1 M hydrochloric acid for 15 min. Separately, solid-liquid extraction was carried in an orbital shaker using 0.1 M hydrochloric acid at 70 °C for 2.5 h. UAE with hydrochloric acid resulted in the highest concentration of laminarin, 5.82% and 6.24% on dry weight basis from A. nodosum and L. hyperborea, respectively. Purification of all extracts was carried out using molecular weight cut off dialysis at 10 kDa. Characterization of the laminarin fraction was carried out using matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Antioxidant activity of A. nodosum and L. hyperborea extracts had 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition levels of 93.23% and 87.57%, respectively. Moreover, these extracts have shown inihibition of bacterial growth of Staphylcoccus aureus, Listeria monocytogenes, Escherichia coli and Salmonella typhimurium.

Optimization of ultrasound assisted extraction of bioactive components from brown seaweed Ascophyllum nodosum using response surface methodology.

The objective of this study was to investigate the effect of key extraction parameters of extraction time (5-25 min), acid concentration (0-0.06 M HCl) and ultrasound amplitude (22.8-114 µm) on yields of bioactive compounds (total phenolics, fucose and uronic acid) from Ascophyllumnodosum. Response surface methodology was employed to optimize the extraction variables for bioactive compounds' yield. A second order polynomial model was fitted well to the extraction experimental data with (R(2)>0.79). Extraction yields of 143.12 mgGAE/gdb, 87.06 mg/gdb and 128.54 mg/gdb were obtained for total phenolics, fucose and uronic acid respectively at optimized extraction conditions of extraction time (25 min), acid concentration (0.03 M HCl) and ultrasonic amplitude (114 µm). Mass spectroscopy analysis of extracts show that ultrasound enhances the extraction of high molecular weight phenolic compounds from A. nodosum. This study demonstrates that ultrasound assisted extraction (UAE) can be employed to enhance extraction of bioactive compounds from seaweed.

Effect of ultrasound pre-treatment on the drying kinetics of brown seaweed Ascophyllum nodosum.

The effect of ultrasound pre-treatment on the drying kinetics of brown seaweed Ascophyllum nodosum under hot-air convective drying was investigated. Pretreatments were carried out at ultrasound intensity levels ranging from 7.00 to 75.78 Wcm(-2) for 10 min using an ultrasonic probe system. It was observed that ultrasound pre-treatments reduced the drying time required. The shortest drying times were obtained from samples pre-treated at 75.78 Wcm(-2). The fit quality of 6 thin-layer drying models was also evaluated using the determination of coefficient (R(2)), root means square error (RMSE), AIC (Akaike information criterion) and BIC (Bayesian information criterion). Drying kinetics were modelled using the Newton, Henderson and Pabis, Page, Wang and Singh, Midilli et al. and Weibull models. The Newton, Wang and Singh, and Midilli et al. models showed the best fit to the experimental drying data. Color of ultrasound pretreated dried seaweed samples were lighter compared to control samples. It was concluded that ultrasound pretreatment can be effectively used to reduce the energy cost and drying time for drying of A. nodosum.

Application of novel extraction technologies for bioactives from marine algae.

Marine algae are a rich source of bioactive compounds. This paper outlines the main bioactive compounds in marine algae and recent advances in novel technologies for extracting them. Novel extraction technologies reviewed include enzyme-assisted extraction, microwave-assisted extraction, ultrasound-assisted extraction, supercritical fluid extraction, and pressurized liquid extraction. These technologies are reviewed with respect to principles, benefits, and potential applications for marine algal bioactives. Advantages of novel technologies include higher yield, reduced treatment time, and lower cost compared to traditional solvent extraction techniques. Moreover, different combinations of novel techniques used for extraction and technologies suitable for thermolabile compounds are identified. The limitations of and challenges to employing these novel extraction technologies in industry are also highlighted.