Near infrared spectroscopy combined with chemometrics as tool to monitor starch hydrolysis

The objective of this study was to evaluate the feasibility of using near infrared (NIR) spectroscopy combined with principal component analysis (PCA) and partial least squares (PLS) regression to monitor the in vitro hydrolysis of different starch substrates. Potato and rice starches, and pre-gelatinised corn starch were used, where samples collected at different time points (5 to 120 min) during the in vitro hydrolysis and analysed using a Fourier transform NIR instrument with a gold-coated integrating sphere (diffuse reflection). PLS regression models between the spectra and reference data yield a coefficient of determination in cross validation (R²_CV) and standard error in cross validation (SECV) of 0.94 and 1105. 8 μg mL^-1; 0.81 and 440.81 μg mL^-1; 0.45 and 338 μg mL^-1; 0.70 and 276 μg mL^-1; 0.75 and 296. 2 μg mL^-1 for the prediction of the concentration of maltose using all samples, rice and potato combined, and pre-gelatinised corn, potato and rice starches analysed separately, respectively. It was concluded that the combination of NIR spectroscopy with both PCA and PLS regression might provide with a rapid and efficient tool to rapidly monitor changes that occur during the in vitro hydrolysis of starch.