Comparative analysis of aroma compounds of African pears via differently coated solid-phase micro-extraction fibres (SPME) using GC-FID and GCMS

Comparative Analysis of Aroma Compounds in African Pear (Dacryodes edulis) Pulp by HS-SPME Coupled with GC-FID and GC-MS

Significance of the Topic

Headspace solid-phase microextraction (HS-SPME) combined with gas chromatography offers a solvent-free, sensitive technique for profiling volatile compounds responsible for fruit aroma. Understanding the aroma profile of African pear is essential for quality control, product development and sensory evaluation in food and flavour industries.

Objectives and Study Overview

This study aimed to identify and quantify the key aroma-active volatiles in the pulp of Dacryodes edulis from Cameroon. A comparative approach evaluated five commercially available SPME fiber coatings to determine the optimal extraction conditions in combination with GC-FID and GC-MS analysis.

Methodology and Instrumentation

• Sample preparation: Ripe Dacryodes edulis fruits were harvested, peeled, and pulp portioned into 60 g aliquots in 240 ml vials.
• SPME fibers: 50/30 µm DVB/Carboxen/PDMS Stable-Flex; 50/30 µm DVB/Carboxen/PDMS; 70 µm Carbowax/DVB-StableFlex; 65 µm PDMS/DVB Stable-Flex; 85 µm Carboxen/PDMS Stable-Flex.
• Extraction: Headspace sampling at 40 °C for 1 hour.
• Gas chromatography: Shimadzu GC-14 with GC-FID (hydrogen carrier gas, temperature program 40 °C to 280 °C) and Shimadzu QP-5000 GC-MS (He carrier, EI 70 eV, scan range 41–450 amu).
• Columns: 30 m FSOT-RSL-200 (0.25 µm film) and 60 m Stabilwax (0.50 µm film).
• Identification and quantification: Retention indices, mass spectral libraries (Wiley, NIST) and published essential oil data; peak area calculations in %.

Main Results and Discussion

More than 50 volatile compounds were detected and over 40 identified. The DVB/Carboxen/PDMS Stable-Flex fiber extracted the widest range of aroma-active compounds. Dominant volatiles in the pulp headspace included α-pinene (47.1–60.5%), β-pinene (7.7–8.2%), myrcene (12.9–14.8%) and limonene (3.4–6.4%). Minor components such as linalool, terpinene-4-ol, camphene and various hexane derivatives contributed green, floral, minty and earthy notes. Aroma impressions correlated well with olfactometric evaluations.

Benefits and Practical Applications

The optimized HS-SPME–GC method enables rapid, solvent-free profiling of fruit aroma profiles, supporting product development, quality assurance and sensory research. Identifying key aroma markers facilitates variety selection and post-harvest monitoring.

Future Trends and Potential Applications

Advancements in SPME fiber chemistries and coupling with two-dimensional GC or high-resolution MS will enhance aroma compound characterization. This approach can be extended to other exotic fruits, processed foods and botanicals, promoting deeper sensorial insights and flavour optimization.

Conclusion

HS-SPME using a DVB/Carboxen/PDMS Stable-Flex fiber combined with GC-FID and GC-MS provided a comprehensive volatile profile of African pear pulp, identifying major terpenes and minor aroma-active compounds. The method proves robust for aroma analysis in fruit research and industry applications.

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