Browsing by Author "Vidovic, Senka"
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- Application of Green Technology to Extract Clean and Safe Bioactive Compounds from Tetradesmus obliquus Biomass Grown in Poultry WastewaterPublication . Vladic, Jelena; Jazic, Jelena Molnar; Ferreira, Alice; Maletic, Snezana; Cvetkovic, Dragoljub; Agbaba, Jasmina; Vidovic, Senka; Gouveia, LuisaABSTRACT: Microalgae are capable of assimilating nutrients from wastewater (WW), producing clean water and biomass rich in bioactive compounds that need to be recovered from inside the microalgal cell. This work investigated subcritical water (SW) extraction to collect high-value compounds from the microalga Tetradesmus obliquus after treating poultry WW. The treatment efficiency was evaluated in terms of total Kjeldahl nitrogen (TKN), phosphate, chemical oxygen demand (COD) and metals. T. obliquus was able to remove 77% TKN, 50% phosphate, 84% COD, and metals (48-89%) within legislation values. SW extraction was performed at 170 degrees C and 30 bar for 10 min. SW allowed the extraction of total phenols (1.073 mg GAE/mL extract) and total flavonoids (0.111 mg CAT/mL extract) with high antioxidant activity (IC50 value, 7.18 mu g/mL). The microalga was shown to be a source of organic compounds of commercial value (e.g., squalene). Finally, the SW conditions allowed the removal of pathogens and metals in the extracts and residues to values in accordance with legislation, assuring their safety for feed or agriculture applications.
- Green approach for the valorization of microalgae Tetradesmus obliquusPublication . Gouveia, Luisa; Jazic, Jelena Molnar; Ferreira, Alice; Maletic, Snezana; Cvetkovic, Dragoljub; Vidovic, Senka; Vladic, JelenaABSTRACT: The main goal of this study was to develop an efficient, green approach for the valorization of Tetradesmus obliquus biomass, with zero waste. This microalga was selected because it is widespread, resistant, easy for cultivation, and fast-growing. In the first step, supercritical carbon dioxide (ScCO2) extraction followed by rapid gas decompression was used for the extraction of biomass. The following step was to apply ultrasound-assisted (UA), microwave-assisted (MA), and subcritical water (SW) extraction on the ScCO2-treated biomass to determine the most efficient processing technology. SW demonstrated to be a superior technique over MW and UA with regard to extraction yield and antioxidant content. Moreover, the chemical and microbiological profiles of SW extracts were determined to evaluate their potential and safety. In addition, to create a procedure with zero waste, the solid waste after SW extraction (residue) was analyzed. The organic profile of extracts and residues contained compounds that belong to groups of aliphatic saturated hydrocarbons, aliphatic unsaturated hydrocarbons, alkylated hydrocarbons, ketones, phenols, and esters. Furthermore, these compounds can be applied in different industries including the pharmaceutical and cosmetic industries. Additionally, the content of metals in residues indicated that this material can be used as animal feed and in agriculture. Finally, a complete reduction of microorganisms present in the initial biomass was obtained for the extracts and residues, indicating their safety.