Determination of reducing sugars in foodstuff applying multivariate second-order calibration

Area of Science:

• Analytical Chemistry
• Chemometrics
• Spectrophotometry

Background:

• Accurate determination of reducing sugars (glucose, fructose, lactose) is crucial for food quality assessment.
• Traditional methods may face challenges with complex food matrices and interfering substances.
• Second-order kinetic-spectrophotometric methods offer enhanced selectivity and sensitivity.

Purpose of the Study:

• To develop and validate a chemometrics-assisted second-order kinetic-spectrophotometric method for simultaneous determination of glucose, fructose, and lactose in food samples.
• To evaluate the method's performance in the presence of spectral and reducing interferents.
• To compare the method's results with a reference High-Performance Liquid Chromatography (HPLC) method.

Main Methods:

• A second-order kinetic-spectrophotometric approach using hexacyanoferrate (HCF) reaction at 70 °C in alkaline medium.
• Chemometric algorithms including Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) in spectral augmentation mode, Unfolded Partial Least Squares (U-PLS/RBL), and Non-linear Partial Least Squares (N-PLS/RBL) were employed.
• Experimental design (central composite design) was used to optimize reaction conditions (pH, temperature, HCF concentration).

Main Results:

• MCR-ALS successfully resolved interfering substances and determined fructose and glucose in validation, test, and real food samples with low limits of detection (LODs).
• U-PLS/RBL and N-PLS/RBL accurately quantified all three sugars in validation and test samples, and successfully determined lactose, glucose, and fructose in real milk samples with low LODs.
• Results obtained using the developed methods were statistically comparable to those obtained by the reference HPLC method.

Conclusions:

• The developed chemometrics-assisted second-order kinetic-spectrophotometric method provides a reliable and accurate approach for determining glucose, fructose, and lactose in food matrices.
• The method demonstrates robustness in the presence of interferents, offering a valuable alternative to conventional techniques.
• The study highlights the potential of MCR-ALS, U-PLS/RBL, and N-PLS/RBL for complex sample analysis in food chemistry.