Microalgae (including the cyanobacteria) are established commercial sources of high-value chemicals such as β-carotene, astaxanthin, docosahexaenoic acid, eicosahexaenoic acid, phycobilin pigments and algal extracts for use in cosmetics. Microalgae are also increasingly playing a role in cosmaceuticals, nutraceuticals and functional foods. In the last few years, there has been renewed interest in microalgae as commercial sources of these and other high-value compounds, driven in part by the attempts to develop commercially viable biofuels from microalgae. This paper briefly reviews the main existing and potential high-value products which can be derived from microalgae and considers their commercial development with a particular focus on the various aspects which need to be considered on the path to commercialisation, using the experience gained in the commercialisation of existing algae products. These considerations include the existing and potential market size and market characteristics of the product, competition by chemically synthesised products or by ‘natural’ compounds from other organisms such as fungi, bacteria, higher plants, etc., product quality requirements and assurance, and the legal and regulatory environment.

High-value products from microalgae—their development and commercialisation

Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

Flocculation as a low-cost method for harvesting microalgae for bulk biomass production.

Research studies on microalgae have increased in the last decades due to the wide range of applications associated to these photosynthetic microorganisms. Microalgae are an important source of oils and other biomolecules that can be used in the production of biofuels and high-valued products. However, the use of microalgae in these green processes is still not economically viable. One of the main costs associated to microalgal production is related to the harvesting process, as it usually accounts for about 20–30% of total cost. Therefore, this review focuses on the main harvesting processes applied to microalgae, presenting the main advantages and disadvantages of each method, to allow the selection of an appropriate procedure to effectively separate microalgal biomass from the culture medium. To reduce the associated costs, it is common to harvest microalgae in a two-step separation: (i) thickening procedures, in which microalgal slurry is concentrated to about 2–7% of total suspended solids; and (ii) dewatering procedures, which result in the concentration of microalgal slurry to 15–25% of total suspended solids. Selection of the adequate harvesting methods depends on the characteristics of the target microorganism and also on the type and value of the end product.

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Harvesting techniques applied to microalgae: A review

Economic and technical problems related to the reduction of petroleum resources require the valorisation of renewable raw material Recently, microalgae emerged as promising alternative feedstock that represents an enormous biodiversity with multiple benefits exceeding the potential of conventional agricultural feedstock Thus, this comprehensive review article spots the light on one of the most interesting microalga Chlorella vulgaris It assembles the history and a thorough description of its ultrastructure and composition according to growth conditions The harvesting techniques are presented in relation to the novel algo-refinery concept, with their technological advancements and potential applications in the market

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Morphology, composition, production, processing and applications of Chlorella vulgaris: A review

In the past decades, food scientists have been searching for natural alternatives to replace synthetic antioxidants. In order to evaluate the potential of microalgae as new source of safe antioxidants, 32 microalgal biomass samples were screened for their antioxidant capacity using three antioxidant assays, and both total phenolic content and carotenoid content were measured. Microalgae were extracted using a one-step extraction with ethanol/water, and alternatively, a three-step fractionation procedure using successively hexane, ethyl acetate, and water. Antioxidant activity of the extracts varied strongly between species and further depended on growth conditions and the solvent used for extraction. It was found that industrially cultivated samples of Tetraselmis suecica, Botryococcus braunii, Neochloris oleoabundans, Isochrysis sp., Chlorella vulgaris, and Phaeodactylum tricornutum possessed the highest antioxidant capacities in this study and thus could be a potential new source of natural antioxidants. The results from the different types of extracts clearly indicated that next to the well-studied carotenoids, phenolic compounds also contribute significantly to the antioxidant capacity of microalgae.

Antioxidant potential of microalgae in relation to their phenolic and carotenoid content

Flocculation of Chlorella vulgaris induced by high pH: role of magnesium and calcium and practical implications.

Pectin represents a very heterogeneous biopolymer whose functionality remains largely puzzling. The link between the pectin fine structure and functional properties with relevance to plant growth and development, as well as food processing, is continually being explored. This review describes the current knowledge of pectin structure–function relationships. Key mechanisms dictating pectin structure–function relationships are discussed, including the polymer biosynthesis, cross-linking mechanisms, enzymatic and nonenzymatic conversion reactions, solubility properties, and more. Insight into the polymer structure–function relationships is highlighted by examining traditional and advanced methodologies used in pectin research. The role of pectin in modulating the quality characteristics of plant-based foods is underlined while pin-pointing some of the main challenges and perspectives. An integrated approach using the pectin structure–function relationship in the precision engineering of mechanical properties of tissue-based systems is proposed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2009.00071.x

Pectins in Processed Fruits and Vegetables: Part II—Structure–Function Relationships

Comparative study of the cell wall composition of broccoli, carrot, and tomato: structural characterization of the extractable pectins and hemicelluloses.

Ilse Fraeye

Papers

Antioxidant potential of microalgae in relation to their phenolic and carotenoid content

Flocculation of Chlorella vulgaris induced by high pH: role of magnesium and calcium and practical implications.

Pectins in Processed Fruits and Vegetables: Part II—Structure–Function Relationships

Comparative study of the cell wall composition of broccoli, carrot, and tomato: structural characterization of the extractable pectins and hemicelluloses.

Dietary enrichment of eggs with omega-3 fatty acids: A review