Aroma Profiling of Commercial Poi Products in Fresh and Aged States Using Comprehensive Two-Dimensional Gas Chromatography

Importance of the Topic

Poi, a traditional fermented taro product, holds cultural, nutritional, and sensory value. Profiling its volatile organic compounds (VOCs) provides insights into fermentation chemistry, supports quality control, and informs product development in food science and industry.

Objectives and Study Overview

This study examined three commercial poi brands to achieve three main goals: establish a core VOC profile, compare VOC compositions among products, and determine changes during fermentation by analyzing fresh and aged samples using comprehensive two-dimensional gas chromatography combined with quadrupole mass spectrometry and flame ionization detection (GC×GC-qMS/FID).

Methodology

Samples were prepared according to manufacturers’ instructions. Fresh poi was analyzed immediately, and aged samples were analyzed after seven days of storage. VOCs were extracted from 5 g of sample using a divinylbenzene/carbon wide range SPME Arrow fiber in headspace vials. GC×GC-qMS/FID analysis employed a TRACE 1300 GC/FID coupled with an ISQ 7000 single quadrupole MS and a reverse fill/flush modulator. Data processing included peak integration via mass spectral libraries and multivariate visualization (PCA, box plots, volcano plots). A 30 % detection threshold within each class filtered the compound list.

Instrumentation Used

• Gas chromatograph: TRACE 1300 GC with split inlet (250 °C, 20 mL/min split flow)
• Mass spectrometer: ISQ 7000 single quadrupole (ion source 280 °C, 40–300 m/z, 41.5 scans/s)
• Detector: Flame ionization detector (FID), broad linear range
• Modulation: Reverse fill/flush modulator, 2.5 s period
• Columns: 1D Rxi-624Sil MS (30 m × 0.25 mm × 1.4 µm), 2D Stabilwax (5 m × 0.25 mm × 0.25 µm)
• SPME Arrow fiber: 1.5 mm wide sleeve divinylbenzene/carbon wide range (CWR)

Main Results and Discussion

A total of 56 VOCs were identified across all samples, with 24 core compounds present in every brand. Fresh samples contained 14 unique VOCs, while aged samples yielded 18 unique compounds. Each brand exhibited 2–8 product-specific VOCs. Fermentation markers such as 1-pentanol, acetic acid, and 2,5-dimethylfuran were detected in aged samples. Principal component analysis showed distinct aromatic profiles for fresh samples by brand, converging into more similar profiles post-fermentation. Chemical class analysis revealed that esters and carboxylic acids dominated in two brands, alcohols increased upon aging across all brands, and ketones decreased with fermentation. Sensory descriptors shifted from predominantly fruity, floral, and sweet in fresh samples to tangy, acidic, and savory notes in aged samples.

Benefits and Practical Applications

Comprehensive VOC profiling of poi improves understanding of fermentation chemistry and flavor development. The findings support quality assurance in production, enable authentication of commercial brands, and guide process optimization to achieve desired sensory attributes.

Future Trends and Potential Applications

Advances may include coupling GC×GC with high-resolution mass spectrometry for more comprehensive non-targeted analyses, integration of real-time online monitoring of fermentation, application of machine learning for pattern recognition, and combining chemical profiling with sensory and nutritional data to develop predictive models for product quality.

Conclusion

This study demonstrated the utility of GC×GC-qMS/FID in differentiating VOC profiles of three commercial poi brands and tracking changes from fresh to aged states. A core set of compounds was established, brand-specific markers were identified, and key fermentation-related VOCs were highlighted. The approach offers valuable tools for food scientists and industry professionals to monitor and enhance product quality.

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