Microalgae are a promising alternative source of lipid for biodiesel production. One of the most important decisions is the choice of species to use. High lipid productivity is a key desirable characteristic of a species for biodiesel production. This paper reviews information available in the literature on microalgal growth rates, lipid content and lipid productivities for 55 species of microalgae, including 17 Chlorophyta, 11 Bacillariophyta and five Cyanobacteria as well as other taxa. The data available in the literature are far from complete and rigorous comparison across experiments carried out under different conditions is not possible. However, the collated information provides a framework for decision-making and a starting point for further investigation of species selection. Shortcomings in the current dataset are highlighted. The importance of lipid productivity as a selection parameter over lipid content and growth rate individually is demonstrated.

Lipid productivity as a key characteristic for choosing algal species for biodiesel production

Pretreatment of lignocellulosic biomass for enhanced biogas production.

Importance of algae oil as a source of biodiesel

Microalgae feedstocks are gaining interest in the present day energy scenario due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrients contents. All of these properties render them an excellent source for biofuels such as biodiesel, bioethanol and biomethane; as well as a number of other valuable pharmaceutical and nutraceutical products. The present review is a critical appraisal of the commercialization potential of microalgae biofuels. The available literature on various aspects of microalgae, e.g. its cultivation, life cycle assessment, and conceptualization of an algal biorefinery, has been scanned and a critical analysis has been presented. A critical evaluation of the available information suggests that the economic viability of the process in terms of minimizing the operational and maintenance cost along with maximization of oil-rich microalgae production is the key factor, for successful commercialization of microalgae-based fuels.

Commercialization potential of microalgae for biofuels production

Microalgae biotechnology has recently emerged into the lime light owing to numerous consumer products that can be harnessed from microalgae. Product portfolio stretches from straightforward biomass production for food and animal feed to valuable products extracted from microalgal biomass, including triglycerides which can be converted into biodiesel. For most of these applications, the production process is moderately economically viable and the market is developing. Considering the enormous biodiversity of microalgae and recent developments in genetic and metabolic engineering, this group of organisms represents one of the most promising sources for new products and applications. With the development of detailed culture and screening techniques, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. This review article discusses the technology and production platforms for development and creation of different valuable consumer products from microalgal biomass.

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Bioprocess engineering of microalgae to produce a variety of consumer products

Twelve algal strains representing the classes Cyanophyceae, Prymnesiophyceae, Bacillariophyceae, Rhodophyceae, Cryptophyceae, Chlorophyceae, Xantophyceae and Eustigmatophyceae were selected mainly from the culture collection of the Norwegian Institute for Water Research (NIVA). The algae were grown as continuous cultures in a 1.8 l. reactor, internally illuminated with an 11 W fluorescent tube. The retention time was adjusted in the range 2–4 days to fit the growth rate of the algae. The growth responses and fatty acid composition were analysed. The maximum production rate was obtained with Pseudokirchneriella subcapitata (0.63 g 1−1 day−1) and the lowest with Porphyridium cruentum 0.13 g 1−1 day−1. Arachidonic acid (AA) and eicosapentaenoic acid (EPA) were the dominating polyunsaturated fatty acids (PUFAs) in P. cruentum, while only EPA accumulated in Phaeodactylum tricornutum. Docosahexaenoic acid (DHA) was the major PUFA in Isochrysis galbana, while Pavlova sp. had both EPA and DHA. This is the first report on the fatty acid profiles of Nannochloropsis oceanica, Chroococcus sp., Synechococcus sp. and Tribonema sp.

https://moritz.botany.ut.ee/~olli/b/Patil07.pdf

Fatty acid composition of 12 microalgae for possible use in aquaculture feed

Effect of different steam explosion conditions on methane potential and enzymatic saccharification of birch.

Quantitative determination of saturated-, monounsaturated- and polyunsaturated fatty acids in pork adipose tissue with non-destructive Raman spectroscopy.

The therapeutic significance of polyunsaturated fatty acid (PUFA) especially docosahexaenic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (AA) has been demonstrated by recent clinical and epidemiological studies. Fish oils are the major commercial source of long chained ω3 PUFA. Global production of farmed fish and shell fish has more than doubled in the past two decades, trends toward intensification and greater control over nutritional input resulting in increased demand for wild fish for feed. Feed is the largest production cost for commercial aquaculture (e.g. most farming of salmon, other marine finfish, and shrimp), and thus improving feed efficiency in industrial systems is already a priority. Moreover, fishmeal prices have risen in real terms in the past three decades and are likely to increase further with continued growth in demand. The possible decline of commercial fish stocks calls for research in alternative sources of PUFA. Considerable evidence has indicated that ω3 fatty acids in fish oils actually derive from zooplankton that consumes algae. Further the microalgae may have superior lipid stability compared to traditional PUFA because they are naturally rich in antioxidant carotenoids and vitamins and because lipids are microencapsulated by the algae cell wall.

Microalgae as source of polyunsaturated fatty acids for aquaculture

Quality changes during 3 wk of refrigerated storage (1.3 degrees C) were studied on pre-rigor filleted farmed Atlantic cod packed in modified atmosphere (MAP, 60% CO2 and 40% O2) or vacuum. The packages of MAP contained either a CO2 emitter and low gas volume to product volume (g/p ratio) of 1.3, or a 3.9 g/p ratio and no emitter. The CO2 level remained stable or increased in the packages with CO2 emitter, whereas the CO2 level in the packages with no CO2 emitter decreased to 40% after 4 d of refrigerated storage. High levels of oxygen in the gas mixture prevented formation of trimethyl amine (TMA) during storage of the MA-packed fish, whereas the TMA content increased significantly after 10-d storage in vacuum. MA-packed samples had the highest values of 1-penten-3-ol. Sensory scores of sour, sulfur, and pungent odors were significantly higher for vacuum-packed cod compared to the 2 MA-packaging methods measured 14 d after slaughtering. No differences in sensory scores were observed between the 2 methods of MAP, and shelf life of these samples seemed to be 14 to 21 d. Cod samples packaged in vacuum packages had higher pH values compared to ordinary MAP and packages containing a CO2 emitter. Bacterial growth was inhibited by MAP and resulted at the end of the storage period in dominance of Carnobacterium and some Photobacterium. In MA packages with high O2 levels the Photobacterium was inhibited. It is concluded that CO2 emitters are well suited for reduction of transport volume for MA-packaged farmed cod.

Quality Changes during Refrigerated Storage of MA-Packaged Pre-rigor Fillets of Farmed Atlantic Cod (Gadus morhua L.) Using Traditional MAP, CO2 Emitter, and Vacuum

Elisabeth Olsen

Papers

Fatty acid composition of 12 microalgae for possible use in aquaculture feed

Effect of different steam explosion conditions on methane potential and enzymatic saccharification of birch.

Quantitative determination of saturated-, monounsaturated- and polyunsaturated fatty acids in pork adipose tissue with non-destructive Raman spectroscopy.

Microalgae as source of polyunsaturated fatty acids for aquaculture

Quality Changes during Refrigerated Storage of MA-Packaged Pre-rigor Fillets of Farmed Atlantic Cod (Gadus morhua L.) Using Traditional MAP, CO2 Emitter, and Vacuum