Harvesting microalgae for health beneficial dietary supplements

Abstract Microalgae are an abundant and diverse resource that can help ease the growing pressure on the food and dietary supplements industry. Microalgae can be used either as whole biomass to increase the overall food content of lipids, carbohydrates, and proteins. They can be also grown to produce high levels of specific metabolites that are extracted and purified, such as omega-3 fatty acids, antioxidants and phycobiliproteins. However, technological and economical barriers within downstream processing, in particular microalgae harvesting, continue to limit large-scale production. Harvesting can affect both process economics and the end-use market, as many existing methods involve large energy expenditures or use of potentially harmful chemicals which would not satisfy government regulations. This review discusses the requirements of harvesting microalgal dietary supplements, and provides a comparison of harvesting techniques currently used in industries, along with other promising methods that could be utilized in the future. Based on a comparison of methods, centrifugation remains a top choice despite energy costs, and flotation techniques that utilize promising bioflocculants that avoid the toxicity associated with traditional flocculants have significant potential for harvesting microalgae to produce dietary supplements.