Attenuated Total Reflectance-Fourier transform infrared spectroscopy coupled with chemometrics for the rapid detection of coconut water adulteration.

Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), in combination with chemometrics, was explored as a rapid method of detecting sugar adulteration in coconut water. In a simulated experiment, coconut water was substituted with binary sugars, mixed sugars, and high fructose corn syrup and discriminated using the fingerprint infrared band region between 1200 and 950 cm. Principal component analysis (PCA) performed on data pre-processed by the Savitzky-Golay smoothing and gap-segment derivative, revealed data clusters discernible by the type and level of substituted sugars, enabling visual diagnosis of the similarity and anomalous features in the dataset. Statistical performance metrics following a cross-validated partial least square (PLS) regression indicated the prediction of adulterant sugars at single-digit percent substitutions. A parallel exploratory analysis of 31 different commercial coconut water samples showed a distinct PCA clustering for samples bearing the label "added sugar", suggesting the potential use of the methods to screening samples for undeclared sugar additions.