Optimized extraction, purification and stabilization of hydroxycinnamic acids from halophytes

Human activity, such as agriculture, problems with water management systems and deforestation, are some of the reasons soil salinization has reported to be one of the major reasons for agriculture land degradation. Agriculture land degradation increases continuously due to unsustainable agricultural actions and land use, as over-irrigation with fresh water increases soil salinity, and irrigation water is taken from limited and vitally important fresh water reservoirs, thus leading to rising water tables. As fresh water for food production is a scares resource in many places of the world, coupled with an increase in human population, it is of interest to investigate crops capable of cultivation on barren soil, and irrigation with saltwater without an excess use of fresh water. This problem is decreasing the area of farmable land for the European farmers, but the cultivation of edible halophyte plants for food and pharmaceuticals might reverse the trend of salinization, and furthermore increase the profit and jobs for European farmers. 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 its life cycle, the amount of phenolics found is increased, and the plant can now be harvested for phenolic extraction. The possibility of a 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 molecular 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 designed. A simple solvent extraction includes biomass submerged in a solvent. This simple extraction will only extract the free phenolics in the biomass 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 structure, 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 extraction can be done by methods of prep-HPLC in a laboratory. The raw extract can be further processed using chemical encapsulation methods to stabilize the phenolics, as phenolics are very prone to degradation due to their antioxidant properties.
Therefore, this PhD study will focus on optimizing the extraction of phenolics in halophytes by the use of green sustainable solvents possibly assisted by ultrasound, enzymes, or others, for sensitive phytochemical extraction. The study will also include 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.