Nondestructive Detection of Melamine in Milk Powder by Terahertz Spectroscopy and Correlation Analysis Algorithm

Abstract

Investigations were initiated for developing a rapid and nondestructive detection method to measure the illegal additive of melamine into milk powder by using terahertz (THz) spectroscopy and the correlation analysis algorithm. The absorption coefficients exhibited a maximum absorption peak at 2.04 THz, which would normally increase along with the concentration of melamine additive. In the current study, correlation analysis was carried out to select a pair-variable at 2.04 and 2.34 THz for improving the predictive ability of the multiple linear regression (MLR) model. Compared with the partial least square (PLS) model in full spectrum, the MLR model for powder samples could be considered successful in terms of quality control of milk powder with correlation coefficient R2 of 0.97 and root mean square error of prediction (RMSEP) of 1.38%. At the same time, the MLR model was simple and easier to interpret than the PLS one. The results of the research suggested that THz spectroscopy in combination with the correlation analysis algorithm has a significant potential in the quantitative analysis of the illegal additive of melamine in milk powder.