基于荧光光谱—模拟退火法年份白酒中乙酸浓度预测研究

近年来年份白酒市场中行业规范有所缺失,因此年份白酒的研究具有深远意义和市场价值.白酒中单体物质的浓度会随着白酒的年份改变,检测白酒中单体浓度可用来鉴定白酒质量及其年份.基于国内某品牌年份原桨白酒的三维荧光光谱,对其中乙酸浓度进行了建模研究.对原始光谱进行了小波分解和求导预处理.研究发现小波分解第一层和第二层呈噪声特征,...

Prediction of Acetic Acid Concentration in Chinese Liquors Based on Fluorescence Spectrumand Simulated Annealing Algorithm

In recent years, the industry of vintage liquor market is not standardized. It is of deep significance and market value to study year liquor. The concentration of monomer in liquor will change with liquor age, so the detection of monomer concentration in liquor can be used to identify liquor quality and age. In this paper, based on the three-dimensional fluorescence spectrum of a certain domestic puree liquor brand, the concentration prediction model of acetic acid is studied. The main contents and innovations are as follows: Firstly, wavelet decomposition and derivative preprocessing are performed on the original spectrum. It is found that the first layer and the second layer of the wavelet mainly present the characteristics of noise, the concentration information is mainly distributed in the third and fourth layer signals. The intensity distribution of fluorescence emission spectra with different excitation wavelengths is different. At present, there is no unified method to select the appropriate excitation wavelength. According to wavelet decomposition signal, this article introduced effective signal strength and obtained the proper modeling excitation wavelength (200 nm). The derivative spectrum has more detailed features than the original spectrum, which can improve the spectral resolution. Secondly, the correlation between acetic acid concentration and fluorescence spectrum was studied. In general, the correlation between the original fluorescence spectrum and the concentration of acetic acid is not high. The correlation between the wavelet decomposition spectrum and derivative spectrum and the concentration is more than 0.8 and shows more discrete correlation peaks. Therefore, the wavelet decomposition spectrum and derivative spectrum contain more information about the acetic acid concentration, which has a wider distribution than the original spectrum’s. Finally, the partial least squares (PLS) multiple regression model of acetic acid concentration was studied based on fluorescence spectra and simulated annealing. The results show that the root means square error of the prediction set of acetic acid concentration in the original spectrum is as high as 70.03 mg·L-1, so its model’s effect is poor. Wavelet decomposition spectrum and derivative spectrum have better prediction effect because the multiple correlations between the spectra is reduced, and the resolution is improved. The second derivative spectral modeling is the best. The root mean square error of the prediction set is 20.32 mg·L-1, and the correlation coefficient is 0.9998. The spectral information density curve based on 1000 simulated annealing algorithms shows that the second derivative spectrum contains more acetic acid concentration information than the original spectrum. This study provides a simple optical method for predicting the concentration of substances in the year liquor. The research methods have a certain reference value for studying the concentration prediction of multi-component gradual change system.