Determination of colorant type in yellow tofu using Vis-NIR and SW-NIR spectroscopy

Abstract

A method that can detect colorant type in food is requisite against illegal practices that used non-food-grade colorants in food. In this study colorant types of yellow tofu were identified using visible near-infrared (Vis-NIR) and shortwave near-infrared spectra (SW-NIR) spectroscopy. Chemometrics analysis using partial least square-discriminant analysis (PLS-DA) and principal component analysis-linear discriminant analysis (PCA-LDA) were used to classify natural colorants, non-food-grade colorants, and food-grade colorants in yellow tofu. The best model obtained using Vis-NIR had calibration accuracy and reliability of 100% for both PCA-LDA and PLS-DA. The best model yielded by SW-NIR had calibration accuracy of 76% and 28% reliability for PLS-DA, and accuracy of 92% and 76% reliability for PCA-LDA. The result showed that Vis-NIR spectroscopy was superior to SW-NIR spectroscopy to distinguish the colorant type used in yellow tofu. Moreover, PCA-LDA yielded better accuracy and reliability compared to PLS-DA.