A major challenge for humanity in this century is the increased demand for nutritious food in consideration of the growing world population, consumption levels, dietary shifts and the consequent environmental degradation. Photoautotrophically grown microalgae are a possible solution to tackle these problems. These microalgae can be grown on non-arable land and fix CO2. However, photoautotrophic microalgae-based biorefinery concepts are currently not competitive compared to other established production systems. Therefore, innovative upstream processes need to be developed to increase the competitiveness of photoautotrophic microalgae biorefinery concepts. Abiotic sub-lethal stress induction via nanosecond pulsed electric field (nsPEF) treatment might be a viable process to increase the efficiency of photoautotrophic microalgae biorefinery concepts. Pulsed electric field processing is an emerging non-thermal treatment with various applications in the food and bio-based industry.
After numerous experiments in the lab, including quite some though times in front of the results, I was finally able to present my latest results at the IFT-EFFoST 2018 International Nonthermal Processing Workshop in Naples, Italy and the 11. Bundesalgenstammtisch in Karlsruhe, Germany.
During both conferences, I delightfully saw there is quite a transformation happening in the food and bio-based research community. Non-thermal processes to increase quality and nutritional aspects in food in Italy and whole microalgae-based biorefinery concept in Germany are headlines of the occurring transformation. Even greater was my personal experience, as I realized that my interdisciplinary collaborators and I work in a field that has applicability in both research areas. Thorough system characterization to increase the technology readiness level of nsPEF and conventional PEF applications in the food sector and growth stimulation of photoautotrophic microalgae, as well as microbial contamination control in the bio-based industry, have a high relevance for both future microalgae and food processing.
Currently, PEF is widely applied in the food industry to increase juice yield, shelf-life extension of fresh juice and most prominently, tissue softening of e.g. potato tubers to increase the quality of the final product, e.g. fries and chips. However, the current applications are not suitable to solve the current challenges in sustainable food supply for a growing world population. Therefore, I was glad to show novel application potentials of the PEF technology to meet these requirements, which have been developed in collaboration with an interdisciplinary research team. Reducing the pulse width to nanoseconds increases the intracellular effect of the applied electric fields. Thereby, we were able to show an increase in prokaryotic microalgae (Arthrospira platensis) cell proliferation.
These results could strongly contribute to the increased demand for nutritious food in consideration of the growing world population. It was highly inspiring for me to discuss the potential of our findings with various researches from the field. From these discussions, an idea for a closed biorefinery approach developed in my mind. Combining nsPEF with conventional PEF applications would enable a microalgae-based circular economy. Recycling of microalgae growth media as substrate for further microalgae cultivation combined with nsPEF to increase the cell proliferation in combination with conventional PEF applications for cascade extraction of valuable compounds from microalgae, bear a huge potential. Not only could the potential of microalgae itself, cultivation on non-arable land and CO2 fixation be used, but the sustainability of the system could be increased by simultaneously increasing the applicability of microalgae in the food and bio-based industry.
Buchmann, L., Frey, W., Gusbeth, C., Ravaynia, P.S., Mathys, A. 2019. Effect of nanosecond pulsed electric field treatment on cell proliferation in microalgae. Bioresource Technology 271: 402-408
Buchmann, L., Bloch, R., Mathys, A. 2018. Comprehensive pulsed electric field (PEF) system analysis for microalgae processing. Bioresource Technology 265: 268–274
Buchmann, L., Böcker, L., Frey, W., Haberkorn, I., Nyffeler, M., Mathys, A. 2018. Energy input assessment for nanosecond pulsed electric field processing and its application in a case study with Chlorella vulgaris. Innovative Food Science and Emerging Technologies 47: 445–453
ABOUT THE AUTHOR
Leandro Buchmann is doing his doctoral project on pulsed electric fields (PEF) process development and applications at ETH Zurich in the Sustainable Food Processing Laboratory under the supervision of Prof. Alexander Mathys. Leandro aims to contribute to a better understanding of PEF processes and thereby increase the technology readiness level. More info can be found here: https://www.linkedin.com/in/leandro-buchmann-30a417116/.