* Philippidis 2020 Philippidis, A.; Velegrakis, M.  
be affected by the employed extraction techniques and conditions, so there is a need for optimized methods that can bring value and market interest to the final products. This work focused on the optimization of C-PC and \(\beta\)-carotene extraction techniques from Spirulina biomass and their application to lab-cultured microalgae strains isolated from diverse habitats of Greece. Selected Spirulina samples were further fractionated in order to evaluate the antioxidant activity of different fractions. Several techniques of cell disruption were tested for C-PC extraction (sonication, magnetic stirring, etc.) and optimized experimental parameters included an initial pre-treatment of the sample for 2 h, at 25 \({}^{\circ}\)C, using a phosphate buffer (C = 0.01 M) and a solvent to biomass ratio equal to 10:1 followed by a 5 min sonication. In case of \(\beta\)-carotene, optimum extraction conditions included intense stirring for 1.5 h using a mixture of acetone and ethanol. Both methods were applied under optimum conditions for C-PC and \(\beta\)-carotene extraction. The results showed that C-PC content ranged from 1.1 to 61.4 mg C-PC/g d.w., while C-PC purity ratio (A\({}_{620}\)/A\({}_{280}\)) ranged from 0.15 to 1.16. Although _Arthospira_ spp. have shown low C-PC content values (2.4-3.6 mg C-PC/g d.w.), their crude extracts exhibited elevated C-PC purity (0.71-0.85). \(\beta\)-Carotene content ranged from 0.1 to 180.7 \(\mu\)g/g d.w. with _Arthospira_ spp. being among the strains with the highest content (135.3 \(\mu\)g/g d.w.). Extraction and fractionation of selected Spirulina samples were performed using solvents with different polarities (water/methanol, methanol, chloroform, acetone/ethanol, ethyl acetate, and n-butanol) and the antioxidant activity of all fractions was evaluated using the DPPH and ABTS assays. Results revealed that methanolic extracts exhibited the highest antioxidant activity, followed by acetone/ethanol extracts. The present study clearly demonstrates that significant amounts of C-PC and \(\beta\)-carotene can be extracted under optimal conditions from local microalgae strain cultures, while a fractionation protocol applied to Spirulina biomass samples produced fractions enriched with metabolites that exhibit high antioxidant activity. Financial support is acknowledged by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH--CREATE--INNOVATE (Project acronym: CO\({}_{2}\) Bioproducts; project code: T1 EDK-02681). ## References  
* Grosshagauer et al. 2020 Grosshagauer, S.; Kraemer, K.; Somoza, V. The true value of spirulina. _J. Agric. Food Chem._**2020**, _68_, 4109-4115. * Pagels et al. 2021 Pagels, F.; Vasconcelos, V.; Guedes, A.C. Carotenoids from cyanobacteria: biotechnological potential and optimization strategies. _Biomolecules_**2021**, _11_, 735. * Romay et al. 2003 Romay, C.; Gonzalez, R.; Ledon, N.; Remirez, D.; Rimbau, V. C-Phycocyanin: A biliprotein with antioxidant, anti-inflammatory and neuroprotective effects. _Curr. Protein. Pept. Sci._**2003**, \(4\), 207-216. * _17.9. Optical Spectroscopy as an Alternative Tool for Honey Analysis_
* Boumpoulaki 1 2 2 1 2 1 2 1 1 2 1 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 2 1 2 2 1  
that spectroscopic techniques provide a rapid, useful tool that requires no sample pre-treatment for the evaluation of honey according to its botanical origin and physicochemical parameters [1,2]. ## References  
* Orfanakis et al. (2021) Orfanakis, E.; Markoulidakis, M.; Philippidis, A.; Zoumi, A.; Velegrakis, M. Optical spectroscopy methods combined with multivariate statistical analysis for the classification of Cretan thyme, multi-floral and honeybee honey. _J. Sci. Food Agric._**2021**, _101_, 5337-5347. * Karoui et al. (2007) Karoui, R.; Dufour, E.; Bosset, J.-O. ; De Baerdemaeker, J. The use of front face fluorescence spectroscopy to classify the botanical origin of honey samples produced in Switzerland.