Now showing 1 - 2 of 2
  • Publication
    Ultrasound-assisted processing of Chlorella vulgaris for enhanced protein extraction
    The green microalga Chlorella vulgaris is a promising source of proteins of high nutritional value for the food industry. The present study aims to improve the recovery of proteins and umami free amino acids from C. vulgaris by exploring the use of ultrasound following multiple approaches including ultrasound-assisted single solvent extraction, ultrasound-assisted sequential solvent extraction and ultrasound-assisted enzymatic extraction. Ultrasound-assisted single solvent extraction using an alkaline solvent during 10 min provided equivalent protein recoveries to those obtained in control experiments macerating the biomass during 18 and 24 h. Ultrasound-assisted sequential solvent extraction using 0.4 M NaOH followed by 0.4 M HCl achieved a protein recovery of 79.1 ± 5.3%, 1.32-fold higher than the control experiments without ultrasound for 1 h. Ultrasound-assisted enzymatic extraction using lysozyme resulted in protein recoveries ranging from 33 to 42%, and these extracts also contained a high percentage of umami free amino acids. Ultrasound-assisted enzymatic extraction with protease enhanced the recovery of proteins (58–82%), although the extracts had low percentage of umami free amino acids. The scanning electron microscopy imaging revealed that ultrasound-assisted solvent extraction and ultrasound-assisted enzymatic extraction significantly changed the morphology of the cell surface.
    Scopus© Citations 67  765
  • Publication
    An investigation into the efficacy of ozone for inactivation of microalgae cells in photobioreactors
    (American Society of Agricultural and Biological Engineers (ASABE), 2013-07) ; ; ; ;
    The sterilisation of photobioreactors is paramount to successful cultivation of microalgae. Due to the adhesive nature of microalgae, fouling of the light transmitting surfaces can be problematic. Traditional methods of sterilising photobioreactors between batches involve ultrasound, autoclaving or as seen in recent times, the photobioreactor incorporates a cleaning system. The objective of this project was to look at an alternative method of sterilisation. A preliminary study was carried out to determine the efficacy of ozone as treatment for the algae strain Dunaliella tertiolecta. Algae cultures at 104 cells CFU mL-1 were exposed to 3-51 μg mL-1 of ozone at different time periods (0-80 sec) and constant gas flow rates of 0.125 and 0.25 L min -1. Inactivation rates for total reduction of D. tertiolecta were found to increase significantly with an increase in ozone concentration and treatment time. This study supports the proposed mechanism of cell inactivation by ozone that causes cell membrane destruction and finally cell death. Therefore, it was found that ozone can be used to effectively eradicate microalgae in photobioreactors.
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