(4es) Developing Bio-Based Solutions for Harnessing Natural Resources

Bio-based solutions leveraging renewable resources to produce food, non-food products, and biofuels offer a sustainable alternative to current dependence on fossil fuels and traditional manufacturing processes. My research focuses on developing innovative processing methods to upcycle renewable sources into high-value bio-based products. I aim to contribute to a thriving circular economy by minimizing waste and maximizing resource utilization for a more sustainable future.

Agricultural production and food processing generate a significant amount of waste rich in valuable compounds, offering a significant opportunity for resource recovery. My graduate research explored subcritical water (SCW) extraction as a sustainable approach to upcycle these wastes into bio-based products. I focused on developing bioactive extracts rich in antioxidant phenolics from pistachio hull, a major regional food processing waste. Using SCW, I achieved superior extract yields compared to poorly sustainable conventional methods. SCW further allowed me to selectively recover targeted bioactive components in a water-based extract with a tunable composition by processing parameters. These results highlighted the promise of SCW for sustainable production of bioactive extracts from waste, warranting further research on mechanisms, optimization, scalability of SCW processes, and commercial viability of the obtained extracts.

The potential application and commercial success of bio-based products from waste streams rely on rigorous characterization processes for their chemical compositions, potential biological activities, and (techno)-functional properties. Recognizing the critical role of reliable bio-analytical methods, I developed quantitative analytical strategies, particularly involving analytical extraction, chromatographic separation and spectrometric detection methods, to comprehensively characterize both plant materials and bioactive SCW extracts. These methods enabled me to chemically characterize raw materials, track the functional molecules throughout the SCW process, and identify novel structures, degradation products, and functional mechanisms of the extracts and potential final products.

My postdoctoral research further explored the potential of functional bio-based products for both food applications and human health. In the food industry, I focused on addressing the challenge of color instability of anthocyanins, natural pigments, in plant-based foods. I investigated color-enhancing chemical interactions between these coloring pigments and phenolic-rich plant-based extracts. My findings revealed that phenolics can protect anthocyanins from degradation and color loss through intermolecular co-pigmentation, paving the way for developing more stable and sustainable food colorants for the food industry. Additionally, I explored the health effects of natural compounds on cellular metabolism, leveraging expertise in metabolomics and cell biochemistry. My research revealed that select phenolics may modulate cellular energy metabolism, suggesting the potential for developing novel, nature-based therapeutics for diseases like diabetes and cancer.

In addition to my research on natural compounds, I actively collaborated on projects exploring microbial production of commodity chemicals. By applying metabolomics, I contributed to understand how microbes respond metabolically to material-induced stresses. This experience further broadened my knowledge of sustainable resource utilization and supplemented my skills in biology in harnessing natural resources for bioproduction.

All in all, my research experience encompasses all process and product development aspects, from evaluating raw materials to processing and final product formation, positioning me to lead a multi-faceted research program. My expertise particularly lies in three key areas for developing (1) innovative bioprocesses to upcycle waste streams, (2) advanced bio-analytical characterization techniques, and (3) high-value bioproducts with a focus on functionality and sustainability. I am passionate about developing innovative and sustainable bio-based solutions that contribute to a circular economy and a healthier planet. My multidisciplinary background allows me to effectively collaborate and communicate with scientists from diverse fields and institutions to tackle complex research challenges.

Teaching Interests:

Teaching has always been integral to my academic journey through teaching positions and research mentoring experiences. I firmly believe that strong researchers make strong teachers; thus, research and teaching are inseparable. My engineering background shapes my teaching philosophy, prioritizing the development of critical thinking and problem-solving skills in my students. After equipping students with skills to achieve their goals and setting clear objectives, I guide them toward independence, where they can learn to gather resources efficiently and critically evaluate. As in other parts of life, teaching also involves a continuous learning process, as I strive to improve my pedagogical skills through ongoing student mentorship.

My teaching experience encompasses a range of courses relevant to food engineering programs, including department-specific subjects like food analysis, food microbiology, and food engineering unit operations. Building on my research expertise, I can offer courses leveraging chemistry and engineering subjects with practical laboratory components. Specifically, I can offer engineering courses like fluid mechanics, separation processes and process design, complementing my research objectives.

Selected Publications:

1. Xie Y, Erşan S, Guan X, Wang J, Sha J, Xu S, Wohlschlegel J. A, Park JO, Liu C. 2023. Unexpected metabolic rewiring of CO₂ fixation in H₂-mediated materials-biology hybrids. Proceedings of the National Academy of Sciences 120, e2308373120.
2. Guan X, Erşan S, Hu X, Atallah TL, Xie Y, Lu S, Cao B, Sun J, Wu K, Huang Y, Duan Y, Caram JR, Park JO, Liu C. 2022. Maximizing light-driven CO₂ and N₂ fixations in biology-material hybrids. Nature Catalysis 5, 1019-1029.
3. Erşan S, Müller M, Reuter L, Carle R, Müller-Maatsch J. 2022. Co-pigmentation of strawberry anthocyanins with phenolic compounds from rooibos. Food Chemistry: Molecular Sciences 4, 100097.
4. Erşan S, Guclu-Ustundag Ö, Carle R, Schweiggert R. 2018. Subcritical water extraction of phenolic and antioxidant constituents from pistachio (Pistacia vera) hull. Food Chemistry 253, 46-54.
5. Erşan S, Guclu-Ustundag Ö, Carle R, Schweiggert R. 2017. Determination of pistachio hull phenolics by HPLC-DAD-ESI/MSⁿ and UHPLC-PDA-ELSD after ultrasound-assisted extraction. Journal of Food Composition and Analysis 62, 103-114.
6. Erşan S, Guclu-Ustundag Ö, Carle R, Schweiggert R. 2016. Identification of phenolic compounds in red and green pistachio (Pistacia vera) hulls (exo- and mesocarp) by HPLC-DAD-ESI-(HR)-MSⁿ. Journal of Agriculture and Food Chemistry 64, 5334-44.
7. Guclu-Ustundag O, Erşan S, Özcan E, Özan G, Kayra N, Ekinci FY. 2016. Black tea processing waste as a source of antioxidant and antimicrobial phenolic compounds. European Food Research and Technology 242, 1523-1532.