Monitoring of Furan Derivates and Key Aroma Species Simultaneously in Coffee and Coffee Substitutes

Significance of the Topic

Coffee and its substitutes represent a major global industry, with consumer demand for both safety and consistent aroma profiles driving analytical requirements. Thermal processing generates potentially harmful furan derivatives alongside desirable aroma compounds. A robust method capable of quantifying toxic furans while simultaneously profiling aroma-active species is essential for quality control, regulatory compliance, and product development.

Study Objectives and Overview

This study aimed to develop and validate a headspace solid phase microextraction (HS-SPME) combined with gas chromatography time-of-flight mass spectrometry (GC-TOFMS) method for:

• Quantitative determination of furan, 2-methylfuran, 3-methylfuran, and 2,5-dimethylfuran in coffee and coffee substitutes.
• Non-target screening (NTS) of additional volatile and aroma-active compounds within the same analytical run.
• Meeting the performance criteria specified in EU Recommendation 2022/495 for monitoring furans in food matrices.

Methodology

Sample Preparation and Calibration:

• Seven retail coffee substitute samples and a proficiency test instant coffee sample (FAPAS 30119) were analyzed.
• Standard solutions of target analytes at 0.07, 7, and 1400 μg/mL were prepared for calibration curves via multi-point dilutions.
• Samples (100 mg) were combined with 2 mL saturated NaCl solution in 10 mL headspace vials; analyte quantification used the standard addition approach to compensate for matrix effects.

Used Instrumentation

• SPME Fiber: DVB/C-WR 80/10 μm (CTC Analytics).
• GC System: Agilent 7890A with split injection (1:30) at 240 °C.
• Column: HP-INNOWax, 30 m × 0.25 mm ID, 0.25 μm film thickness.
• Oven Program: 35 °C (3 min), ramp 15 °C/min to 100 °C, then 50 °C/min to 220 °C (hold 5 min).
• TOFMS: LECO Pegasus BT, EI source at 230 °C, mass range 35–600 m/z, acquisition at 12 spectra/s.

Main Results and Discussion

Method Validation:

• Limits of quantification (LOQ) of 1 μg/kg for all furans, well below EU thresholds (20 μg/kg for coffee).
• Linearity range from 0.4 to 400 μg/kg with correlation coefficients ≥0.998.
• Repeatability (RSD) between 4% and 19% across analytes (n=6).
• Trueness confirmed via proficiency test with z-scores between –1.4 and 1.1.

Furan Levels in Samples:

• Detected concentrations varied by sample composition; one substitute had all analytes below LOQ.
• Highest furan levels observed in roasted spelt–based substitute.

Non-Target Screening:

• Full volatile profiles captured enabled deconvolution of coeluting peaks and identification of additional toxic or aroma-active compounds.
• Identified species included methoxymethylfuran, furancarboxaldehyde derivatives, several pyrazines, and nonanal with library match scores >850.

Benefits and Practical Applications

• Simultaneous safety monitoring and aroma profiling in a single analysis enhances laboratory efficiency.
• Compliance with EU regulations supports product safety documentation and market authorization.
• High-quality full mass range data facilitate deeper understanding of flavor chemistry and contaminant formation.

Future Trends and Applications

The method can be extended to other thermally processed foods such as baby foods by adjusting sample mass for lower detection limits. Advanced two-dimensional GC, automation of sample preparation, and integration of machine learning for non-target data interpretation are promising developments. Expanded libraries and AI-driven deconvolution will further streamline comprehensive volatile profiling.

Conclusion

The validated HS-SPME–GC-TOFMS approach on the Pegasus BT instrument reliably quantifies low-level furans in coffee matrices and enables concurrent non-target screening of key aroma compounds. The method meets regulatory requirements and offers a versatile tool for flavor and safety assessment in coffee and substitute products.

References

1. Mostafa MM, Ali E, Gamal M, Farag MA. How do coffee substitutes compare to coffee? A comprehensive review of quality, sensory, phytochemicals, health benefits and safety. Food Biosci. 2021;43:101290.
2. EFSA. Risks for public health related to the presence of furan and methylfurans in food. EFSA J. 2017;15(5):5005.
3. Javed F, et al. Formation of furan in baby food products: Identification and technical challenges. Compr Rev Food Sci Food Saf. 2021;20:2699–2715.
4. EFSA. Furan in food – EFSA confirms health concerns. Press release. 2018.
5. EU Commission Recommendation 2022/495 on monitoring the presence of furan and alkylfurans in food. OJ L100. 2022.
6. Zheng LW, Chung H, Kim YS. Effects of dicarbonyl trapping agents on furan formation in canned-coffee models. Food Res Int. 2015;75:328–336.