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Green Engineering for Aroma Stabilization

Periodic Reporting for period 1 - GEAS (Green Engineering for Aroma Stabilization)

Reporting period: 2021-04-01 to 2023-03-31

Aromas represent complex mixtures of volatile organic components (VCs) which are present in various natural resources. Due to their sensory and biological properties, they are implemented in numerous pharmaceutical, food, cosmetics, perfume, and other products.

Given that obtaining natural VCs can be an expensive and complex process, numerous industries use synthetically obtained aromas. However, due to the growth of the consumer demand for natural products produced in an environmentally safe process, there is a constant search to find new, alternative, safe, and cost-effective ways for obtaining natural aroma VCs.

As a response to the conventional, inefficient, and unsafe methods of obtaining natural aroma VCs, supercritical carbon dioxide (ScCO2) extraction was implemented. This procedure implies the application of a green solvent, rational use of resources, and the attainment of a clean and safe product of high quality while avoiding degradation. However, after effective isolation, the limiting factor for a more rational application of VCs is their instability, volatility, and tendency to degradation. Hence, the quality properties of the product may be significantly impaired, which shortens the shelf life of aroma VCs and products.

Deep eutectic solvents (DES) represent a new generation of solvents that have gained a lot of attention due to their properties: they are inexpensive, easy to prepare, biodegradable, and characterized by low or no toxicity. DES possess both thermal and chemical stability, as well as high absorption capacity, making them promising candidates for the stabilization of sensitive components such as aroma VCs.

The goal of the GEAS project was to address these challenges and to develop a new, simple, and green procedure that ensures obtaining and preserving natural VCs in a green way. To accomplish this goal, the integration of green solvents, ScCO2 for the recovery of VCs from natural resources and DES for their stabilization, was investigated and the following objectives were set:
1. To develop and optimize ScCO2 extraction procedures
2. To stabilize aromas with DES
3. To evaluate the potential and stability of new products.

It was concluded that DES can serve as stabilizers of VCs and protection agents against oxidative degradation of the extracts' components obtained by ScCO2. Moreover, this sustainable approach delivers safe and high-quality aroma VCs and products with extended stability at room temperature. The implementation of this solution has the capacity to provide benefits for human health and the environment along with economic advantages important for the industry and large-scale processing systems.
After establishing the optimal conditions for the effective and rational use of natural sources of aromas, the dispersion of the isolated VCs was carried out in different DES by applying depressurization. As natural sources of aroma VCs, the following resources were investigated: Lavandula stoechas, Satureja montana, Rosmarinus officinalis, Mentha piperita, Anethum graveolens, Origanum vulgare, Melissa officinalis, and Zingiber officinale.

The obtained systems (ScCO2+DES) were stored and the VCs stability was monitored during 6 months of storage at room temperature by analyzing headspace profile (HP). Various statistical and chemometric tools were used for data analysis, change detection, and stability assessment over time.

The stability of VCs in different DES was compared with control samples. It was found that significant changes in the HP of the samples occurred during storage. The most common patterns of changes were the evaporation of low-boiling components and oxidation. Additionally, the most significant indicator of reduced stability over time was the formation of new compounds, which can lead to significant degradation of sensory characteristics. In addition, to the potential deterioration of the taste, smell, and texture of the product, these components can also be responsible for manifesting undesirable effects on health.

Changes in volatile profiles and formation of new components were the most prominent in controls, indicating reduced stability of these samples. Moreover, it was established that, although there was a change in the percentage distribution of VCs in ScCO2-DES systems, the changes were significantly less pronounced. The absence of the formation of new components that impair the quality of the product was observed in certain ScCO2-DES systems. For example, for preserving the stability of VCs of L. stoechas, the betaine/ethylene glycol system was the most effective, while the betaine/ethylene glycol and betaine/glycerol/sucrose/water DES mixtures effectively preserved the stability of R. officinalis VCs.

Dissemination activities included publications in scientific journals, presentations at conferences, and presentation of the project results to associates and industry representatives. Additionally, communication of the project activities to different target audiences through popular events was conducted, such as the European Researchers’ Night.
The project represents an approach where the integration of two green solvents which were coupled for the first time provides a solution for efficient attainment and preservation of aroma VCs. By establishing the potential of DES to stabilize aroma VCs, a new indication for the application of DES was created. Moreover, the established sustainable approach brings a multi-aspect socio-economic impact, including benefits for human health, the environment, and economic benefits important for the industrial sector.

The ability to obtain and preserve natural aroma VCs provides safe products for the consumers. The implementation of this solution would bring a rational and effective use of natural resources without solvent waste generation, hence. Consequently, this approach has the potential to reduce environmental pollution.

By implementing project outputs, the industries get the possibility to improve their existing processes which leads to saving resources, improving quality of products, and efficiently meeting the demands of the market for safer and greener products. Apart from extending their duration and ensuring a more rational use of VCs and their natural sources, preservation at room temperature brings additional economic benefits in terms of cost savings related to the transport and storage of these sensitive components. Also, due to the safe profile of DES, these products are ready-to-use products which eliminates the purification step. The integrated application of ScCO2 and DES, prevents losses, degradation, and evaporation that occur during the common VCs preservation procedures. As a result, this could contribute to a greener production at the European level which can have a lasting impact on the quality of life in Europe and its economy by increasing its share on the global market of aromas.

The conclusions of this project represent the basis for further development and implementation of these systems in different areas as the great number of DES components can be applied in food, beverage, pharmaceutical, cosmetic, perfume, and chemical areas. Lastly, the implementation of the established solutions ensures processes with high societal implications that are in accordance with the Sustainable Development Goals agenda, including environmental and economic sustainability, environmental protection, and human well-being.
GEAS Project-medicinal plant, supercritical extract, DES components, ScCO2-DES system