PROJECT TITLE: Optimized extraction, purification and stabilization of hydroxycinnamic acids from halophytes
PhD period: 2020.07.15 – 2023.14.07.
Section: Esbjerg Energy Section
Research Programme: Biogas and Biorefinering
Supervisor: Mette Hedegaard Thomsen
Co-Supervisor: Marco Maschietti
Soil salinization is seen as a major obstacle to overcome for agriculture, and little action is taken on decreasing the amount of salt in the soil. Around the coastal areas in Europe, the presence of reed grasses and other plants thriving in slightly saline conditions is increasing. This is due to the rising of the water table, as a side effect of poor agricultural water management, amongst others. This problem is decreasing the amount of area farmable for the European farmers, but the cultivation of halophyte plants for food and pharmaceuticals might reverse the trend of salinization, and furthermore increase the profit and jobs for European farmers. As a larger landmass can be used for halophyte cultivation, this also means a larger quantity of food grown. Halophytes in the Salicornia genus, commonly known as glasswort, marsh samphire or sea asparagus, are used in the gourmet kitchen, and therefore has a high sales value, making it a valuable food crop to cultivate. The idea of cultivating halophytes, which are known to contain large amounts of antioxidants, for the pharmaceutical industry, could decentralize the extraction and production of high value plant molecules known as phenolics. Extraction of phenolics will not compete with the interest in halophytes as a food source, as the upper part of the plant is harvested for food production, and the plant will continue its life cycle. When the plant reaches the end of the life cycle, the amount of phenolics found is increased, and the plant can now be harvested for phenolic extraction. The possibility of the farmer to extract phenolics on-site, will be due to a safe extraction, without the use of toxic or dangerous chemicals. To determine an extraction process layout, laboratory experiments using different extraction methods need to be set up. Solvent extractions, extracting the molecules of interest that are not bound in the plant cell structure, is an easy method that does not need chemical engineering expertise, once the optimal conditions are specified, and a stable process is determined. The extraction could simply be submerging the biomass in water in a closed vessel without heating, for a given period of time, but the highest amount of antioxidant molecules in plants are bound in the plant cell structure. A method of extracting these bound phenolics is to break the plant matrix, and thereby make the phenolics more accessible for solvent extraction. This release of phenolics can be done by either enzymes or acid/base treatments, but as an upscaled extraction favours the use of non-dangerous chemicals, strong acids or bases will only be used for laboratory characterization work. When the phenolics are extracted from the plant material, a purification of the extract needs to be done. This purification could involve a liquid-liquid extraction using green solvents, and evaporation of solvents, yielding raw dry extract. The raw dry extract can be further processed using chemical encapsulation methods to stabilize the phenolics, as these are very prone to degradation.
Therefore, this PhD study will focus on optimizing the extraction of phenolics in halophytes by the use of green sustainable solvents, isolation and purification of the extract to yield a high concentration of phenolics, stabilization hereof and lastly proposing a biorefinery process layout, mass balance simulation and techno-economic assessment for upscaling the production.
Publications in journals and conference papers may be found at VBN.