[Study on fast discrimination of brands of soy sauce using near infrared spectra]

A new method for the fast discrimination of brands of soy sauce by means of near infrared spectroscopy (NIRS) was developed and these eight kinds of soy sauce had got its "identity card". The experiment adopted typical eight brands of soy sauce which we bought in the market. Total 3 942 frequencies from 7 625 to 3 684 cm(-1) transmit wavelength were gotten to set up a analyses model. In order to handle these data efficiently, after pretreatment, firstly, principal component analysis (PCA) was used to compress thousands of spectral data into several variables and to describe the body of the spectra, the analysis suggested that the cumulate reliabilities of the first eight components was more than 99.99. According to the first eight components, the authors could distinguish some brand of the soy sauce but could not deal with all of them. So the authors chose ANN-BP as further research method. The eight components were secondly applied as ANN-BP inputs. The experiment took total 242 examples of 8 kinds of soy sauce as original model examples and left 10 every kind as unknown samples to predict. Finally, the result indicated the distinguishing rate is 98.75% in 0.98 reliable area. This paper could offer a new method to the discrimination of varieties of soy sauce.