Fast Detection of White Pepper Adulteration using FTIR-ATR Spectroscopy and Chemometrics

Abstract

White pepper is a significant spice in Indonesia; however, powdered white pepper is vulnerable to adulteration, particularly with ingredients such as mung bean flour. Consequently, there is a need for a reliable analytical method to ascertain the authenticity of ground white pepper. This research seeks to establish an approach for authenticating white pepper and detecting the presence of mung bean flour utilizing Fourier Transform Infrared (FTIR) spectroscopy combined with chemometric techniques. The findings indicate that the adulteration patterns of white pepper and its contaminants can be effectively identified using the Partial Least Squares (PLS) method and chemometrics. Partial Least Squares (PLS) is a statistical method employed for regression analysis and modelling complex relationships between independent variables (X) and dependent variables (Y). It is one of the primary methods used in chemometrics because of its effectiveness in handling datasets with numerous variables, which is often the case in chemical analysis and spectroscopy. The second derivative FTIR spectrum in the range of 3712-650 cm⁻¹ was identified as the optimal calibration model. The coefficient of determination (R²) for calibration was 0.9535, while for prediction it was 0.9943. Furthermore, the root mean square error of calibration (RMSEC) was calculated at 4.32, and the root mean square error of prediction (RMSEP) was determined to be 1.38. The PLS Discriminant Analysis (PLS-DA) method also successfully classified pure white pepper samples from those adulterated with various concentrations of mung bean flour.