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

Significance of the Topic

Honey is valued for its nutritional benefits but is prone to adulteration with cheaper sweeteners such as corn syrup or refined sugar, which undermines consumer trust and market integrity. A fast and reliable analytical method is needed to verify sugar composition and detect fraudulent additions.

Objectives and Study Overview

• Develop a quantitative FTIR-ATR approach to measure fructose, glucose, and sucrose in honey.
• Establish criteria to identify adulteration by comparing sugar profiles to expected ratios in pure honey.

Methodology and Instrumentation

• Instrument: Shimadzu IRTracer-100 FTIR spectrophotometer with Quest ATR accessory (ZnSe prism).
• Measurement parameters: 4 cm⁻¹ resolution; 32 scans; 4000–600 cm⁻¹ range; Happ–Genzel apodization; DLATGS detector.
• Sample preparation: Nine commercial honeys diluted to 10 % w/w; standard calibration set of 34 aqueous mixtures spanning 0–15 % each of fructose, glucose, sucrose arranged in a three-dimensional matrix.
• Chemometric analysis: Partial Least Squares regression using 25 calibration and 9 validation samples; calibration models achieved correlation coefficients ≥0.998 and low prediction errors (MSEP, SEP).

Main Results and Discussion

• Calibration models for all three sugars exhibited excellent linearity (R² > 0.998) and minimal error.
• Commercial samples labeled “100 % pure honey” showed elevated glucose and low fructose/glucose ratios (<1), indicating corn syrup addition.
• One sample labeled as partially pure honey contained significant sucrose, suggesting refined sugar adulteration.
• Other grade-marked or unlabeled honeys varied in sugar ratios, reflecting diverse authenticity levels.

Benefits and Practical Applications

• Reagent-free, non-destructive analysis with minimal sample preparation.
• Simultaneous quantification of multiple sugars in a single measurement.
• Suitable for routine quality control in food industry, regulatory labs, and research settings.

Future Trends and Applications

• Extension to detection of additional adulterants and determination of botanical or geographical origin.
• Integration with portable or inline ATR-FTIR devices for on-site and real-time monitoring.
• Advanced chemometric approaches including machine learning and data fusion with NIR or Raman spectroscopy.

Conclusion

The combination of FTIR-ATR spectroscopy and PLS chemometrics offers a straightforward, accurate method to quantify key sugars in honey and detect adulteration. This approach enhances quality control protocols, helping to ensure product authenticity and consumer confidence.

Reference

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