FTIR-ATR Characterization of Commercial Honey Samples and Their Adulteration with Sugar Syrups Using Chemometric Analysis

Significance of the Topic

Honey is a high-value natural product prized for its flavor and potential health benefits. Adulteration with inexpensive sugar syrups erodes consumer confidence, harms market growth, and may misrepresent product quality. Rapid, reliable screening methods are needed to ensure authenticity and protect both consumers and producers.

Study Objectives and Overview

This study demonstrates the use of Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) combined with chemometric analysis to characterize commercial honey samples and detect adulteration with sugar syrups such as corn syrup. Nine different honey products were evaluated to quantify fructose, glucose, and sucrose content and to assess purity claims.

Methodology and Instrumentation

Samples were diluted to 10 % w/w in deionized water. FTIR-ATR spectra were acquired between 4000 and 650 cm⁻¹. Partial Least Squares (PLS) regression was applied to establish calibration models for sugar quantification in a three-dimensional concentration space. Fructose, glucose, and sucrose standards and corn syrup mixtures formed the training set.

Used Instrumentation

• Shimadzu IRTracer-100 FTIR spectrometer
• ZnSe Quest ATR accessory (Specac)
• Deionized water for sample dilution

Main Results and Discussion

PLS analysis provided quantitative estimates of sugar content in each honey sample. Expected ranges for pure honey are approximately 33–43 % fructose, 25–35 % glucose, and 0–2 % sucrose, with a fructose:glucose ratio near 1.2:1. Key findings:

• Samples labeled as 100 % pure honey exhibited elevated glucose levels and reduced fructose:glucose ratios (0.33–0.69), suggesting corn syrup addition.
• Sample #6, advertised as 7 % honey, contained significant sucrose (≈8.9 %) and high glucose, indicating sugar water adulteration.
• Unlabeled products (#7–#9) showed fructose:glucose ratios close to 1, reflecting variable authenticity.

These results highlight the sensitivity of FTIR-ATR coupled with chemometrics for detecting subtle compositional changes due to adulteration.

Benefits and Practical Applications

This approach offers a non-destructive, rapid screening protocol for quality control in honey production and distribution. It eliminates the need for complex sample preparation or reagents, reduces analysis time, and can be integrated into routine laboratory workflows or at-line inspections to safeguard product integrity.

Future Trends and Potential Uses

Advancements may include portable FTIR-ATR devices for field testing, expansion of spectral libraries to cover diverse floral honeys, and incorporation of machine-learning algorithms for improved classification. Similar strategies can be extended to authenticate other natural products such as oils, spices, and herbal extracts.

Conclusion

FTIR-ATR combined with PLS chemometrics provides an effective and efficient method to detect honey adulteration with sugar syrups. The technique’s speed, minimal sample preparation, and quantitative accuracy make it well suited for quality assurance and regulatory monitoring.

References

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