Chemometrics as an aid to quickly evaluate galactomannans through infrared spectroscopy

Galactomannans, composed of galactose and mannose, may form gels and are considered safe because of their non-toxic, biodegradable, and biocompatible nature. As a result, they are widely utilized in the food industry as stabilizers and thickeners. Among galactomannan producing species, guar gum and locust bean gum are particularly important due to their economical relevance. Guar gum and locust bean gum are often adulterated with cellulose gums like xanthan gum and carboxymethyl cellulose (CMC). Adulteration of galactomannans with other gums may introduce uncertainties regarding functionality and complicate quality control, posing a potential problem for the food industry. Among the different techniques which have been used for determining and characterizing galactomannans, Fourier Transform Infrared Spectroscopy stands out. Especially when coupled to Attenuated Total Reflection (ATR), analyses are performed rapidly, with a minimum sample preparation, and without the need for solvent or previous extraction mechanisms. However, food is a very complex matrix that contains a high number of components which generate a multitude of spectral information and large data sets. Consequently, additional data processing tools such as chemometrics are needed to be able to draw useful information from spectra. Our goal in this work is to show how to optimize conditions for instrumental analysis by infrared spectroscopy of galactomannans and its constituent monomers and create a chemometric model where galactomannans could be differentiated as a single group. We successfully optimized the PCA model obtained after chemometric processing of infrared data through reducing dimensions by loadings selection.