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Advancing selectivity in extraction and analysis of bioactive compounds in seaweed and plant-based foods

Year: 2024
Type: dissertation
Abstract: A wide range of biomass resources provides significant opportunities to meetsociety's needs, such as ensuring food nutritional security, responsible use andconsumption. Seaweed, one of the abundant natural resources along the Swedishcoastline and characterized by rapid growth, has attracted significant interest as asource of biomass for various industries, including food, biochemical, and biofuelproduction. Other interesting plant-based biomass, with a wide range of biochemicalcomposition, include berries, which are known for their anthocyanin-rich composition. Extraction and analysis are critical steps in recovering valuablebioactive compounds from biomass, as well as understanding their identity andconcentrations. However, challenges arise due to the diverse chemical properties ofthese compounds, such as varying polarity, stability, and matrix interactions.Additionally, the absence of reference standards for many plant-derived compoundscomplicates the analysis. There is a need for robust and sustainable analyticalprocesses to foster biomass utilization, through both extraction and quantificationof biochemicals. This thesis addresses these challenges by developing quantitative concepts for evaluating extraction performance, focusing on extractability, selectivity, and relative comprehensiveness. Supercritical fluid extraction (SFE) andchromatographic analysis were utilized for bioactive compounds. The researchbegan by formulating quantitative descriptors to measure extraction in terms ofextractability, selectivity, and comprehensiveness. Formulas were derived toestimate selectivity by analysing target components and quantifying potentialinterferences. For example, using carbon dioxide (CO2) with 5% ethanol as a co-solvent in seaweed extraction yielded high selectivity for β-carotene with minimalinterferences. The addition of water increased the extractability andcomprehensiveness of polar compounds but reduced selectivity by co-extractingundesirable compounds like arsenic. Shortening extraction time to 15 minutesreduced accumulation of interferences. The second approach involved evaluating extraction selectivity's impact on chromatographic results, investigated by employing multivariate curve resolution (MCR) on liquid chromatography-diode array data from berry matrices. This method highlighted the varying effects of different extraction methods on the quantification of different classes of bioactive compounds. In general, this was a simplified approach crucial for assessing selectivity and improving the reliability of quantification. To address both selectivity and comprehensiveness in analysis of a broad polarity range of bioactive compounds, a strategy combining SFE and supercritical fluid chromatography (SFC) was developed. An SFC method covering compounds of a wide polarity range ( log P of -0.36 to 15.5) was developed. A short (<10 min) and comprehensive analysis method was attained with SFC, while careful fractionation with SFE also demonstrated the potential for reducing matrix complexity before the chromatography. This was particularly shown by a partial least square (PLS) regression model, which predicted the extractability, as well as showing the selectivity in different SFE fractions. Some of the investigations involved assessing the influence of various food processes, such as storage temperatures and fermentation, on the amounts of bioactive compounds. MCR and evolving factor analysis were used to estimate degradation products during storage. In fermentation studies, metabolite changes varied by strain and matrix, which were mainly associated with enhanced extractability and microbial bioconversion.
Institution: Lund University
Language: English
Subfield: Aquatic Science
Open Access status: green
OpenAlex ID: W7017132533
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