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Development of a Microwave Assisted Cell Disruption of Biomass and Extraction of Valuable Compounds

Periodic Reporting for period 1 - Amicrex (Development of a Microwave Assisted Cell Disruption of Biomass and Extraction of Valuable Compounds)

Reporting period: 2015-05-01 to 2017-04-30

The combination of biomass valorisation, process intensification and green technology is an attractive research challenge for the European Community being in line with the “Resource-efficient Europe” flagship initiatives by optimizing the use of material, energy resources and gaining valuable products with lower impact on our environment and health. The AMICREX project accepted this challenge and aimed to develop an integrated process design for future industrial implementation, where by-products from agro-industrial processes (e.g. carrot peels) were valorised by recovering high-value nonpolar components (e.g. carotenoids, well recognized natural pigments and widely used in the food and cosmetic industries) through a microwave assisted extraction process using selected micro-emulsions as extraction solvent.
The AMICREX concept can be extended to address the challenges proposed by extraction of nonpolar metabolites, especially carotenoids, from other renewable biomass sources. The key aspects of the proposed technology were 1) to avoid the use of hazardous organic solvents in nonpolar compounds’ extraction by using micro-emulsion as extraction media, and 2) to improve extraction kinetics by microwave assisted extraction in order to facilitate the liberation of intracellular compounds and make them available during the extraction process.
The research first focused on the evaluation on the laboratory scale microwave extraction process and on the use of micro-emulsion as extraction solvent combined with wet biomass. Based on the so obtained process and system specifications, the small scale process was aimed to be turned into an industrial design concept through process modelling and simulation.
Overall objective of Amicrex was to address the gaps of the current research by establishing an integrated system for continuous microwave cell disruption and subsequent extraction of valuable compounds from semisolid biomass for future industrial implementation. Moreover, an additional environmental friendly and sustainable approach is targeted by the exclusion of organic solvents in the extraction process using micro-emulsion as extraction media.
By the implementation of the project gaps between multidisciplinary fields of natural sciences and engineering were filled. Moreover, the interdisciplinary scenario between biomass cell disruption, extraction process and micro-emulsion technology was established (Figure 1)
Primarily the characterization of the raw materials was performed via standardized methods. Moreover, their interaction with the electromagnetic field was evaluated under different conditions through dielectric properties measurements. According to the results, complex effect of temperature, moisture and effect of composition differences were observed. Moisture content of the material was found to be critical when assessing temperature dependence for dielectric constant and dielectric loss.
In order to achieve the extraction using a micro-emulsions, first, the stable extraction media, the micro-emulsion was established and optimized. Selected micro-emulsions were able to extract up to 83% more carotenoids from wet carrot peel as the conventional organic solvent, ethyl-acetate.
In parallel, the microwave pre-treatment (MWP) and microwave assisted extraction (MAE) of carotenoids from wet carrot peel were studied in order to attain process performance intensification. Although MAE and MWP resulted in similar yield increment (≈30%) compared to conventional extraction, lower temperature level and shorter extraction time enabled better process performance using MAE.
Based on the specified and previously optimized process requirements an industrial design concept was established, giving ground to the exploitation of the technology to further application using different biomass. The developed concept laid on following criteria: 1) Direct MW energy input from the waveguide into the extraction media. 2) Avoid the use of MW transparent material when transmitting energy from the source to the extraction media due to the assembly difficulties of at connecting points at higher temperatures and pressures. 3) Achieve good field distribution in order to perform volumetric heating. 4) Achieve good mixing level of non-homogeneous material in order to enhance substance diffusion and energy distribution (Figure 2).
Dissemination: The development and update of a project dedicated web site in the framework of Fraunhofer’s network was established at the beginning of the project (www.amicrex.eu). Face-to-face dissemination took place through active participation in conferences, forums, info days and workshops, organized both at the national and EU level, such as the Achema trade fair 2015 (Frankfurt, Germany), AMPERE Conference 2015 (Krakow, Poland), WineSense Spring School 2016 (Valladolid, Spain), European Researcher’s Night 2017 (Budapest, Hungary), Anuga FoodTec trade fair 2018 (Cologne, Germany), among others. Published Online and printed dissemination took place
•Sólyom K., Javaid, A.I. Vásquez-Caicedo A.L. Effect of moisture, temperature and Bulk Porosity of Dielectric Properties of Carrot peel. Proceedings of the 15th International Conference on Microwave and Radio Frequency Heating 2015, Krakow, Poland. pp. 48. ISBN 978.83.928784.4.5
• Solyom K., Rosales Lopez P., Esquivel P., Vásquez-Caicedo A.L. Effect of temperature and moisture contents on dielectric properties at 2.45 GHz of fruit and vegetable processing by-products, accepted for publication in RSC Advances.
Exploitation: Following topics are foreseen to be protected through intellectual property rights in order to maximise the exploitation of results: 1) Combined microwave cell disruption and micro-emulsion extraction of carotenoids form biomass on lab-scale. 2) Verified design concept of the continuous industrial system.
This project exploits a novel green extraction technology, micro-emulsion extraction, where the solute incorporates into the dispersed oil droplets of the emulsion due to their affinity to hydrophobic media. Using a micro-emulsion as extraction medium, organic solvents can be avoided during the process providing a healthier aspect to the end product in an environmentally sound process.
Microwave assisted extraction at atmospheric pressure and under vacuum was found to be successful tools in the course of pigment extraction from biomass. Especially β-carotene was extracted from carrot peel by microwave assisted extraction technique using organic solvent.
The combination of both processes enables the treatment of wet biomass avoiding high energy consumption due to drying process which would be necessary when using organic solvents. Moreover the inclusion of carotenoids into proper micro-emulsion which is acceptable for the food and/or cosmetic industry makes the extract right away available for foreseen applications (Figure 3).
Figure 1. Amicrex, a multidisciplinary approach
Figure 2. Amicrex project structure
Figure 3. Amicrex concept as implemented