Study On Fluorescence Spectral Characteristics Of Several Major Substances In Chinese Aged Liquor

Chinese liquor has a very long history in china.Chinese liquor not only has a mellow taste,but also has been verified to be beneficial to the health of the body.So the Chinese liquor has been favored by cosumers,Chinese aged liquor is the most popular liquor among them.The main substances in Chinese aged liquor are Alcohols?esters?acids?aldehydes and so on.These substances have much influence on the quality of liquor.We measure the three dimensional fluorescence spectrum of these substances and studied their spectral characteristics,analyze the spectrum data by chemometrics method to achieve the quantification of monomer in Chinese aged liquor and predict its year.The specific studies are as follows:we analyzed the three-dimensional fluorescence spectrum of fifteen main substances in Chinese aged liquor,studied there spectral characteristics as well.Compare them with the spectral characteristics of two different flavor Chinese aged liquor,learned that acids and esters has much contribution on the fluorescence of Chinese aged liquor.As the year of Chinese aged liquor grow,the reaction of acids and esters will cause change in the fluorescence range?the number and location of fluorescence peak and the fluorescence intensity of Chinese aged liquor.All of above make a base for the study on the quantitative and year predict of Chinese aged liquor.For the content determination of hexanoic acid in Chinese aged liquor,we propose a method by using three-dimensional fluorescence spectrum combined with alternate fitting residual algorithm(AFR).First,eleven different concentrations of hexanoic acid in ethanol-water solution were made,determine their three-dimensional fluorescence spectra as the calibration set.Then determine the three-dimensional fluorescence spectrum of certain Chinese aged Luzhou-flavor liquor as prediction set,totally five years.The alternate fitting residual algorithm was used to analyze the set and predict the content determination of hexanoic acid.The hexanoic acid concentrations were 0.155%,0.182%,0.217%,0.252%,and 0.287%,respectively.The standard addition method and high performance gas chromatography were used to verify the prediction results.For the standard addition method,the correlation coefficient between the real concentration and the predicted concentration was 0.9926.For the high performance gas chromatography,the correlation coefficient between the real concentration and the predicted concentration was 0.9959.The results show that this method can effectively predict the concentration of hexanoic acid in Chinese aged Luzhou-flavor liquor.In order to determine the vintage of white wine,a method using Pearson coefficient combined with multi-dimensional partial least squares(NPLS)to predict the year of white wine was proposed.Firstly,the three-dimensional fluorescence spectrum of two kinds of Chinese aged liquors were determined,include twelve years of Luzhou-flavor and 11 years of sesame-flavor.The Pearson coefficients of the data points and Chinese liquor years in the fluorescence spectrum matrix were measured.According to the value of the coefficients,different regions of the spectrum matrix were selected,and the white wine year was predicted by using a multi-dimensional partial least squares algorithm.The region which has highest cofficient with year has the best predict result.For Luzhou-flavor liquor,the average absolute error between the predict year and the real year is 0.91 years;the sesame-flavor liquor is 1.20 years.This result is better than the prediction results of other regions or the full spectrum matrix.For Luzhou-flavor liquor,the main substances likely to be present in the region which has the best predict result is ethyl caproate;for sesame-flavor liquor,are ethyl acetate and ethyl butyrate.The results show that Pearson's coefficient combined with multi-dimensional partial least squares algorithm can effectively improve the accuracy of predicting the year of Chinese aged liquor.At the same time,this method can preserve the effictive data to the greatest degree,for further analyze the substance which has higher linear correlation with liquor year.