Prediction of Rhodamine B Dye Content in Chilies Paste Using VIS-NIR Spectroscopy

Chili is an agricultural product that is used as a spicy seasoning because it produces a hot effect with striking color and can be processed into various products, such as chili paste. However, it was found that some sellers misused the harmful Rhodamine B (RB) dye in chili paste to maintain the color in order to maximize profits without considering the health impact of consumers. In this study, a method was developed to predict RB in chili paste samples non-destructively using the VIS- NIR instrument combined with the Partial Least Square Regression (PLS) chemometric method to build a calibration model to measure RB content. Red curly chilies in good condition without blemishes were washed and then ground into chili paste products as samples in this study. The samples were divided into four variations of RB concentration, namely 0 ppm, 250 ppm, 500 ppm, and 1000 ppm. The chili paste spectra were acquired at a wavelength of 450-950 nm and several pre- treatments spectra were performed. The best calibration model that can be generated using pre- treatment multiplicative scatter correction (MSC) has a calibration value of R² of 0.96, SEC of 70.69, and RPD of 4.52. This shows that a non-destructive method for predicting RB concentrations in chili paste using VIS-NIR spectroscopy combined with chemometric analysis produces a good measurement method for screening applications.