Determination of sugars in aqueous mixtures using mid-infrared spectroscopy

The combination of mid-infrared (MIR) spectroscopy and multivariate statist ics for determination of glucose, fructose, and sucrose in aqueous mixtures was investigated. Spectra of different samples were recorded in the MIR ra nge between 400 and 4000 nm, Aqueous mixtures of 10, 20, and 40% total suga rs with different combinations of glucose, fructose and sucrose were used f or calibration and validation studies. Spectral wave number region from 700 to 1530 cm(-1) was selected for Principal Component Regression (PCR) and P artial Least Square regression (PLS) to develop calibration models for suga r content determination (%, w/v) in liquid foods. Results from the PLS-I (f irst derivative) models were slightly better than those obtained with other used calibration models. Merging of the 10, 20, and 40% calibration data i nto single calibration set enabled the prediction (average standard error o f calibration, SEC = 0.34) of individual sugars in the entire range accurat ely. The squared correlation (R-2) values for the calibrated models for glu cose, fructose and sucrose were 0.997 0.998, and 0.997 respectively, betwee n the predicted values and actual values. The calibrations were successfull y applied to predict sugar contents in complex mixtures and commercial beve rages Results indicated that fourier transform infrared (FTIR) spectroscopy cart be used for rapid detection of sugars in complex mixtures.