Quantitative Analysis of Sugars (Fructose, Glucose, and Sucrose) in Honey by FTIR

Significance of the Topic

Honey is valued for its vitamins, minerals and bioactive compounds, but economic adulteration with cheaper syrups undermines consumer confidence and market integrity. Rapid, reliable detection of sugar adulterants is essential for quality control in the food industry.

Goals and Overview

This study demonstrates a quantitative method to determine fructose, glucose and sucrose levels in honey using Fourier transform infrared spectroscopy combined with chemometric analysis. The objectives were to construct a robust calibration model from standard sugar mixtures and to apply it to nine commercial honey samples diluted to 10% w/w, identifying potential additions of corn syrup or refined sugar.

Methodology

• Sample preparation: Standard mixtures covering 0–15% w/w of each sugar formed a three-dimensional training matrix. Nine commercial honey samples were diluted to 10% w/w in water.
• Spectral acquisition: Measurements conducted in attenuated total reflectance mode, capturing spectra between 4000 and 600 cm–1.
• Chemometric analysis: Partial least squares regression with five factors per sugar. Calibration built on 25 standard samples and validated with nine held-out samples.

Used Instrumentation

• Fourier transform infrared spectrophotometer: IRTracer-100.
• Single-bounce attenuated total reflectance accessory: Quest ATR with ZnSe prism.
• Detector: DLATGS.
• Acquisition parameters: 4 cm–1 resolution, 32 scans accumulation, spectral range 4000–600 cm–1, Happ–Genzel apodization.

Main Results and Discussion

The PLS models achieved correlation coefficients above 0.998 for all sugars, with mean square error of prediction below 0.003 and standard error of prediction around 0.05% w/w. Distinct IR absorption bands allowed discrimination of fructose, glucose and sucrose. Analysis of commercial honeys revealed that products labeled as 100% pure honey exhibited elevated glucose relative to fructose, indicating corn syrup addition. One sample showed high sucrose content, suggesting refined sugar use. Grade A and unlabeled samples displayed variable fructose to glucose ratios consistent with mixed syrup adulteration.

Benefits and Practical Applications

The proposed FTIR-PLS method is rapid, non-destructive and requires minimal sample preparation. It enables routine screening for sugar adulteration in honey, supporting quality assurance and regulatory compliance in food production and distribution.

Future Trends and Applications

1. Extension of calibration models to detect additional adulterants and authenticate floral or geographic origin.
2. Development of portable FTIR systems and handheld ATR probes for on-site testing.
3. Integration with advanced machine learning algorithms to enhance predictive performance.
4. Creation of shared spectral libraries and cloud-based analytics for real-time monitoring across supply chains.

Conclusion

FTIR spectroscopy combined with chemometric modeling provides an efficient and accurate approach for quantifying fructose, glucose and sucrose in honey. The method successfully identified adulteration patterns in commercial samples, demonstrating its value for routine quality control in the food industry.

References

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