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Microalgae have been long recognized as potential food and feed solution, since they are able to meet the population growth on demand for a more sustainable food and feed, especially with respect to protein production. In addition, bioactive components, such as eicosapentaenoic acid (EPA), with well-known antioxidant and anti-inflammatory properties, can be extracted and incorporated in food supplements. Microalgae cultivation and processing becomes even more sustainable if simultaneously coupled to green technologies for the environmental protection. One of the most promising techniques is the supercritical fluid extraction which allows to extract bioactive compounds without loss of their activity and free from extraction solvents. In this work, a pilot scale supercritical CO2 (ScCO2) extraction plant was exploited for performing the extraction of active components from microalgae biomass potentially usable in the food and the feed sectors. Nannochloropsis gaditana microalga was selected as natural producer of EPA. The extract obtained after ScCO2 tests was enriched of EPA and protein, therefore suitable for food applications. The exhausted biomass, having a high content of carbohydrates and total dietary fiber, might be proposed as feed suppl

Microalgae represent one of the most interesting biological source, since they are relatively simple microorganisms containing high-value compounds with potential applications in numerous industrial sectors. The global nutraceutical market is well developed and with an enormous potential for growth: suffice to say that it has shown considerable growth with a value in 2016 between 168 and 174 billion euros, with a growth forecast that will allow it to reach between 285 and 313 billion euros in 2024. In accordance with the National Center for Biotechnology Information, by 2050, microalgae will constitute ~18% of protein source among the more diverse market. Healthy properties and excellent nutritional values have been conferred to microalgae, with particular regard to the high content of carbohydrates, vitamins, carotenoids and polyunsaturated fatty acids (PUFAs). The omega-3 PUFAs are extremely important throughout life and are a dietary need found predominantly in Nannochloropsis gaditana oleaginous microalga. In fact, although fish contain long-chain omega-3, they acquire PUFAs mainly from their microalgal diet. Additionally, considering depleting fish supplies, the use of microalgae as alternative raw material might be considered of increasing importance in the near future. Herein we report the assessment of the economic feasibility of an integrated process which allows to extract PUFAs from Nannochloropsis gaditana, by taking into account the main operational parameters able to influence the final products yield.

The Supercritical Fluid Extraction (SFE) technology is currently used in many industrial fields thanks to the advantages that it can offer. Experimental tests are carried out for different purposes such as decaffeination of coffee/tea, extraction of aromas and herbal flavours as well as spices, extraction of fats and oils, extraction of cholesterol and extraction of alcohol from beverages. SFE plants safety is closely linked to the high pressure they operate, a condition that can lead to a risk status for plant operations and above all workers. For this reason it is necessary to adopt preventive safety measures and a risk analysis is the means that allows to define and examine hazardous scenarios in order to identify safety devices. Risk scenarios related to an extraction plant as explosions are analysed through methods based on indices determination such as the Fire and Explosion Index (F&EI), the Safety Weighted Hazard Index (SW&HI) and the Probit method. This work presents the risk analysis of a SFE plant named “Luwar” using the commercial software “Phast & Safeti” provided by the DNV GL Company. In the plant is used CO2 as extraction fluid and the process purpose is valuable compounds extraction from microalgae. The risk analysis is performed on the extraction vessel considering the plant placed inside a structure (indoor condition). The results allow to identify two risk parameters, i.e. the distance and the area within which CO2 concentration in the air assumes a value considered unsafe for human health. On the basis of the outputs it is possible to identify the safety system to be adopted in order to limit the damage deriving from the occurrence of a risk situation.

Fungal contamination poses at risk the whole food production chain - from farm to fork - with potential negative impact on human health. So far, the insurgence of pathogens has been restrained by the use of chemical compounds, whose residues have gradually accumulated determining toxic effects in the environment. Modern innovative techniques imply the use of natural and eco-sustainable bioactive plant molecules as pathogens and pests-control agents. These may be profitably recovered in large amounts at the end of industrial milling processes. This is the case of the non-digestible hull of common buckwheat (Fagopyrum esculentum Moench), a natural source of polyphenols, tocopherols, phytosterols and fatty acids. We extract these compounds from the hull of buckwheat; apply them to Aspergillus flavus - aflatoxin producer - under in vitro conditions, checking their ability to inhibit fungal growth and aflatoxin biosynthesis. Moreover, a solvent free method implying the adoption of supercritical CO2 as solvent was set up to extract lipophilic molecules from the buckwheat’ hulls. Positive results in controlling fungal growth and aflatoxin biosynthesis let infer that the extracts could be further tested also under in vivo conditions.

In this article, microalgae Nannochloropsis sp. was used for fatty acid (FA) extraction, using a supercritical fluid-carbon dioxide (SF-CO2) extraction method. This study investigated the influence of different pre-treatment conditions by varying the grinding speed (200−600 rpm), pre-treatment time (2.5−10 min), and mixing ratio of diatomaceous earth (DE) and Nannochloropsis sp. biomass (0.5−2.0 DE/biomass) on FAs extraction. In addition, the effect of different operating conditions, such as pressure (100−550 bar), temperature (50−75 °C), and CO2 flow rate (7.24 and 14.48 g/min) on eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) recovery, was analyzed. Experimental data evidenced that, keeping constant the extraction conditions, the pre-treatment step enhanced the FAs extraction yield up to 3.4 fold, thereby the maximum extracted amount of FAs (61.19 mg/g) was attained with the pre-treatment with a ratio of DE/biomass of 1 at 600 rpm for 5 min. Moreover, by increasing both SF-CO2 pressure and temperature, the selectivity towards EPA was enhanced, while intermediate pressure and lower pressure promoted DHA recovery. The highest amount of extracted EPA, i.e., 5.69 mg/g, corresponding to 15.59%, was obtained at 75 °C and 550 bar with a CO2 flow rate of 14.48 g/min, while the maximum amount of extracted DHA, i.e., ~0.12 mg/g, equal to 79.63%, was registered at 50 °C and 400 bar with a CO2 flow rate of 14.48 g/min. Moreover, the increased CO2 flow rate from 7.24 to 14.48 g/min enhanced both EPA and DHA recovery.

Lutein has several benefits for human health, playing an important role in the prevention of age-related macular degeneration (AMD), cataracts, amelioration of the first stages of atherosclerosis, and some types of cancer. In this work, the Scenedesmus almeriensis microalga was used as a natural source for the supercritical fluid (SF) extraction of lutein. For this purpose, the optimization of the main parameters affecting the extraction, such as biomass pre-treatment, temperature, pressure, and carbon dioxide (CO2) flow rate, was performed. In the first stage, the effect of mechanical pre-treatment (diatomaceous earth (DE) and biomass mixing in the range 0.25–1 DE/biomass; grinding speed varying between 0 and 600 rpm, and pre-treatment time changing from 2.5 to 10 min), was evaluated on lutein extraction efficiency. In the second stage, the influence of SF-CO2 extraction parameters such as pressure (25–55 MPa), temperature (50 and 65 °C), and CO2 flow rate (7.24 and 14.48 g/min) on lutein recovery and purity was investigated. The results demonstrated that by increasing temperature, pressure, and CO2 flow rate lutein recovery and purity were improved. The maximum lutein recovery (~98%) with purity of ~34% was achieved operating at 65 °C and 55 MPa with a CO2 flow rate of 14.48 g/min. Therefore, optimum conditions could be useful in food industries for lutein supplementation in food products.