Potato taste defect (PTD) in coffee analyzed via two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry

A Rising Star in Separation Science

Dr. Cain's journey in analytical chemistry began during her undergraduate studies, where mentorship from Dr. Sarah Rutan and Dr. Marianne Collinson sparked her passion for chromatography. This early exposure to developing stationary phase gradients for LC columns set her on a path that would lead to significant contributions in both liquid and gas chromatography.

"I don't know something about seeing peaks coming off a column and seeing that either your modification worked or it didn't work in the anticipation of that just really drew me into chromatography," Dr. Cain reflected on her initial fascination with the field.

Innovative Research on Coffee Quality

Dr. Cain's award-winning work focused on investigating potato taste defect (PTD) in coffee using comprehensive two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry. This research, conducted in collaboration with Seattle University and a coffee roaster, aimed to uncover the complex volatile profile associated with PTD.

The study employed headspace solid-phase microextraction (HS-SPME) coupled with GC×GC-TOFMS to analyze roasted Arabica coffee samples. Dr. Cain optimized the extraction conditions to balance analyte signal maximization with efficient run times, reducing the extraction time from 60 minutes to 30 minutes while maintaining signal quality.

Groundbreaking Findings

The research identified 359 class-distinguishing analytes related to PTD, providing unprecedented insights into this coffee defect. Key findings include:

1. A significant drop in desirable coffee volatiles: About 300 analytes, including pyrazines and furans responsible for cocoa, nutty, and roasted notes, showed decreased signals in PTD-affected samples.

2. Increase in specific compounds: PTD samples exhibited higher levels of phenols and phenylindanes, potentially linked to increased chlorogenic acid content in green coffee beans affected by microbes.

3. Comprehensive volatile profile: The study expanded our understanding of PTD beyond the known biomarker 2-isopropyl-3-methoxypyrazine (IPMP), revealing a complex interplay of volatile compounds.

Implications for the Coffee Industry

Dr. Cain's research provides valuable insights that could help coffee farmers and the industry address PTD:

- Enhanced understanding of PTD's impact on coffee aroma and flavor
- Potential for developing new strategies to combat the antestia bug responsible for initiating PTD
- Opportunities for further research into the biochemical pathways leading to PTD

The Power of GC×GC Technology

Dr. Cain highlighted the advantages of comprehensive two-dimensional gas chromatography over traditional one-dimensional GC:

- Increased selectivity through complementary column chemistries
- Improved peak capacity and resolution
- Enhanced ability to separate complex mixtures

"In a 2D chromatogram, we can actually improve upon that unresolved hump and help actually resolve out a lot of those analytes," Dr. Cain explained, emphasizing the technique's power in analyzing complex samples like coffee volatiles.

Advice for Early Career Scientists

When asked about advice for aspiring analytical chemists, Dr. Cain emphasized the importance of thinking broadly and making connections across different areas of research:

"I really tried to focus on in my research is always expanding out and thinking about the broader picture... I think that's where a lot of really great science occurs is at those types of intersections."

She also stressed the importance of embracing failure as a learning opportunity and persevering through the challenges of research.

Looking to the Future

Dr. Cain sees exciting developments on the horizon for separation science, including:

- Continued improvements in column technology and multidimensional separations
- Advancements in non-targeted analysis techniques
- Integration of machine learning and artificial intelligence in data analysis

As she continues her postdoctoral research, Dr. Cain aims to bridge the gap between GC and LC techniques, exploring both volatile and non-volatile analytes to solve complex analytical challenges.

Conclusion

Dr. Caitlin Cain's innovative work in gas chromatography, particularly her research on potato taste defect in coffee, exemplifies the cutting-edge science being conducted in the field of separation science. Her insights not only advance our understanding of complex analytical problems but also have real-world implications for industries like coffee production.