Extraction of oil and carotenoids from pelletized microalgae using supercritical carbon dioxide

Can Growth of Nannochloropsis oculata under Modulated Stress Enhance Its Lipid-Associated Biological Properties?

Nannochloropsis oculata is well-recognized as a potential microalgal source of valuable compounds such as polyunsaturated fatty acids, particularly, eicosapentaenoic acid (EPA). The content and profile of these lipids is highly dependent on the growth conditions and can, therefore, be tailored through modulation of the growth parameters, specifically, temperature. Moreover, biological activities are composition dependent. In the present work, lipid extracts obtained from N. oculata, grown under constant temperature and under modulated temperature stress (to increase EPA content; Str) were characterized by GC-FID and several bioactivities were evaluated, namely, antioxidant (L-ORAC_FL), cytotoxic (MTT), adipolytic, anti-hepatic lipid accumulation (steatosis), and anti-inflammatory properties. Both extracts exhibited antioxidant activity (c.a. 49 µmol Trolox_equivalent/mg_extract) and the absence of toxicity (up to 800 µg/mL) toward colon and hepatic cells, adipocytes, and macrophages. They also induced adipolysis and the inhibition of triglycerides hepatic accumulation, with a higher impact from Str. In addition, anti-inflammatory activity was observed in the lipopolysaccharide-induced inflammation of macrophages in the presence of either extract, since lower levels of pro-inflammatory interleukin-6 and interferon-β were obtained, specifically by Str. The results presented herein revealed that modulated temperature stress may enhance the health effects of N. oculata lipid extracts, which may be safely utilized to formulate novel food products.

Research advancement and commercialization of microalgae edible oil: a review

The global food crisis has led to a great deal of attention being given to microalgal oil as a sustainable natural food source. This article provides an overview of the progress and future directions in promoting the commercialization of microalgal edible oils, including microalgal triglyceride accumulation, suitable edible oil culture strategies for high nutritional value, metabolic engineering, production, and downstream technologies. The integration of the production process, biosafety, and the economic sustainability of microalgal oil production are analyzed for their critical roles in the commercialization of microalgal edible oil to provide a theoretical and scientific basis for the comprehensive development and utilization of microalgal edible oil. © 2021 Society of Chemical Industry.

Microalgae for high-value products: A way towards green nutraceutical and pharmaceutical compounds

Microalgae is a renewable bioresource with the potential to replace the conventional fossil-based industrial production of organic chemicals and pharmaceuticals. Moreover, the microalgal biomass contains carotenoids, vitamins, and other biomolecules that are widely used as food supplements. However, the microalgal biomass production, their composition variations, energy-intensive harvesting methods, optimized bio-refinery routes, and lack of techno-economic analysis are the major bottleneck for the life-sized commercialization of this nascent bio-industry. This review discusses the microalgae-derived key bioactive compounds and their applications in different sectors for human health. Furthermore, this review proposes advanced strategies to enhance the productivity of bioactive compounds and highlight the key challenges associated with a safety issue for use of microalgae biomass. It also provides a detailed global scenario and market demand of microalgal bioproducts. In conclusion, this review will provide the concept of microalgal biorefinery to produce bioactive compounds at industrial scale platform for their application in the nutraceutical and pharmaceutical sector considering their current and future market trends.

The Realm of Microbial Pigments in the Food Color Market

Colors are added to food items to make them more attractive and appealing. Food colorants therefore, have an impressive market due to the requirements of food industries. A variety of synthetic coloring agents approved as food additives are available and being used in different types of food prepared or manufactured worldwide. However, there is a growing concern that the use of synthetic colors may exert a negative impact on human health and environment in the long run. The natural pigments obtained from animals, plants, and microorganisms are a promising alternative to synthetic food colorants. Compared to animal and plant sources, microorganisms offer many advantages such as no seasonal impact on the quality and quantity of the pigment, ease of handling and genetic manipulation, amenability to large scale production with little or no impact on biodiversity etc. Among the microorganisms algae, fungi and bacteria are being used to produce pigments as food colorants. This review describes the types of microbial food pigments in use, their benefits, production strategies, and associated challenges.

Optimization and Comparison of Three Cell Disruption Processes on Lipid Extraction from Microalgae

This study reports on the optimization of the operating conditions using response surface methodology and a comparative study of three promising technologies of cell disruption (bead milling, microwaves and ultrasound) to increase the lipid extraction from Nannochloropsis oceanica, Nannochloropsis gaditana and Tetraselmis suecica. Central composite designs were used for the optimization of ultrasound and microwave processes. The performance of the cell disruption processes in breaking down microalgae cells is dependent on the strain of microalgae. Microwaves (91 °C for 25 min) were the most efficient for the recovery of lipids from N. oceanica, reaching a lipid content of 49.0% dry weight. For N. gaditana, ultrasound process (80% of amplitude for 30 min) was the most efficient in terms of lipid recovery (21.7% dry weight). The two aforementioned processes are ineffective in disturbing T. suecica whatever the operating conditions used. Only the bead milling process at low flow feed rate with 0.4 mm zirconia beads made it possible to extract 12.6% dry weight from T. suecica. The fatty acid profiles of N. oceanica and T. suecica are affected by the cell disruption process applied. The calculation of specific energy consumption has shown that this criterion should not be neglected. The choice of the most suitable cell disruption process can be defined according to numerous parameters such as the microalgae studied, the total lipid extracted, the fatty acids sought, or the energy consumption.

Progress in the physicochemical treatment of microalgae biomass for value-added product recovery

Interest in microalgae-derived products is growing, mostly due to their unique characteristics and range of industrial applications. To obtain different products, one must employ specific pretreatments that retain the properties of the biologically active compounds extracted from microalgae biomass; thus, new extraction techniques require frequent upgrades. Due to increased interest in economically viable and ecologically friendly processes, new extraction methods that can be incorporated into microalgae biorefinery systems have become the main focus of research. Therefore, this review aims to address the potential applications, future prospects, and economic scenario of the new physicochemical treatments used in the extraction of bioactive microalgae compounds.

Macrocystis pyrifera source of nutrients for the production of carotenoids by a marine yeast Rhodotorula mucilaginosa

AIMS

To evaluate an aqueous extract of Macrocystis pyrifera as a nutrient source for the production of carotenoids by a marine Rhodotorula mucilaginosa isolated from seaweed samples.

MATERIALS AND RESULTS

The effect of different culture conditions on the concentration of biomass and total pigments was evaluated using a Box-Behnken experimental design. The seaweed extract contained 15% w w-1 of protein and 20% w w-1 of carbohydrate; the main sugar in this fraction was trehalose (78%). The culture conditions that maximize the total pigment concentration (1·84 ± 0·03 mg l-1 ) were initial pH equal to 7, yeast extract as nitrogen source at a concentration of 4 g l-1 , seaweed extract concentration at 25% v v-1 , incubation performed at 25°C and 150 rev min-1 during 6 days. Under optimal growth conditions, three carotenoids were identified among the pigments produced by R. mucilaginosa, lycopene (38·4 ± 9·4%), β-carotene (21·8 ± 1·5%) and astaxanthin (1·8 ± 0·3%).

CONCLUSIONS

Carotenoids of commercial interest (lycopene, β-carotene and astaxanthin) can be produced using a marine R. mucilaginosa cultivated with an aqueous extract of M. pyrifera as nutrient source. The total pigment concentration in the culture ranged between 0·82 and 1·84 mg l-1 , and was significantly affected by the concentration of the seaweed extract, and yeast extract.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work demonstrates that M. pyrifera can be used as a nutrient source for the production of carotenoids by the marine yeast.

Production of new activated bio-carbons by chemical activation of residue left after supercritical extraction of hops

A technology of activated bio-carbons production from the residue left after supercritical extraction of hops is described. The effect of the variant of chemical activation and impregnation ratio on the physicochemical properties as well as sorption capacity towards toxic gas of acidic character (nitrogen dioxide), basic organic dye (aqueous solution of methylene blue - MB) and iodine was investigated. The materials obtained were activated bio-carbons of well-developed surface area ranging between 897 and 1095m²/g, showing clearly acidic character of the surface. The sorption tests results proved that chemical activation of the residue left after supercritical extraction of hops allows obtaining activated bio-carbons with very high sorption capacity towards nitrogen dioxide, reaching to 77.2 and 155.3mg/g in dry and wet conditions, respectively. The maximum sorption capacity of the adsorbents towards methylene blue was 328.75mg/g, while towards iodine 1815mg/g. The equilibrium data for aqueous solution of MB were analyzed by the Langmuir and Freundlich models, whereas the kinetics of the adsorption process was studied using pseudo-first and second-order models. According to the obtained data, the adsorption of MB from aqueous solution is better described by Langmuir model and pseudo-second order kinetic model.

Continuous production of biodiesel from microalgae by extraction coupling with transesterification under supercritical conditions

Raw material for biodiesel has been expanded from edible oil to non-edible oil. In this study, biodiesel continuous production for two kinds of microalgae Chrysophyta and Chlorella sp. was conducted. Coupling with the supercritical carbon dioxide extraction, the oil of microalgae was extracted firstly, and then sent to the downstream production of biodiesel. The residue after decompression can be reused as the material for pharmaceuticals and nutraceuticals. Results showed that the particle size of microalgae, temperature, pressure, molar ration of methanol to oil, flow of CO₂ and n-hexane all have effects on the yield of biodiesel. With the optimal operation conditions: 40mesh algae, extraction temperature 60°C, flow of n-hexane 0.4ml/min, reaction temperature: 340°C, pressure: 18-20MPa, CO₂ flow of 0.5L/min, molar ration of methanol to oil 84:1, a yield of 56.31% was obtained for Chrysophyta, and 63.78% for Chlorella sp. due to the higher lipid content.