Protein Aqueous Solution And The Quality Of Baijiu Studied By Vibrational Spectroscopy

Vibrational spectroscopy is a technology that can directly detect the vibrational information of molecular groups.Its peak information reflects the environment and movement around the molecule.Therefore,vibrational spectroscopy can be used to analyze the interaction between different substances.In addition,since the intensity of the vibration spectrum is related to the content of the substance,the substance can also be quantitatively analyzed.Since the vibration spectrum having a short measurement time,simple,non-destructive of the sample,etc.,it has been used in various fields.In the thesis,we proposed some novel difference spectrum and ratio spectrum analysis methods.These methods were used to study the interaction or content of certain substances.This thesis mainly describes how to use Raman spectroscopy and Fourier infrared spectroscopy combined with correlation analysis methods to study protein aqueous solutions and Baijiu.The main research contents involved are:Quantitative estimation of the hydration number in the protein aqueous solution by Fourier infrared spectroscopy;Analyze the content of acids and esters in Baijiu and the quality grade of Baijiu by using vibration spectrum combined with difference spectrum method;Raman spectroscopy combined with fluorescence background distinguishes the blended Baijiu(Sanjiu)from brand Baijiu.The specific research process is as follows:(1)Using Fourier infrared spectroscopy for analysis and calculation,a new method for quantitatively estimating the hydration number of protein is proposed.First,we prepared and measured a series of infrared spectra of Gdn Hcl-water solution and DMSO-water solution before and after adding fixed mass lysozyme;After a series of analysis,the peak information reflecting the interaction with water in Gdn Hcl and DMSO was obtained;Next,we drew the graph of the spectral peak information with the change of the mass fraction,and obtained the offset of the mass fraction of the two types of solution graphs;Finally,the offset is substituted into the calculation formula to obtain the hydration number of lysozyme.The results we get are consistent with the theoretical estimates and the numbers obtained in the literature,indicating that this method is more reliable.(2)Raman spectroscopy and Fourier infrared spectroscopy were used to analyze the quality grade and acid ester content of Baijiu.We first measured the Raman spectra and Fourier infrared spectra of some Baijiu and ethanol-water solutions,and subtract the spectrum of ethanol-water solution from the spectrum of Baijiu,we get the Raman and Fourier infrared spectra of the acids and esters;Afterwards,by analyzing and calculating the intensity or full width at half maxima of some characteristic peaks of the acid and ester spectra,we obtained a spectroscopic analysis method that can detect the quality grade of Baijiu and the change of acid ester content;Finally,the same method was used to analyze the infrared spectrum of yellow rice wine and wine,which proved that the method was also suitable for extracting trace elements in other wines(3)Raman spectroscopy was used to study the brand Baijiu and bulk liquor(Sanjiu).First,we measured the Raman spectra of 56 groups of Sanjiu and 7 groups of brand Baijiu,found the Sanjiu have a certain fluorescent background;Through specific analysis of the normalized Raman spectra,we propose that the ratio of the fluorescence background to the intensity of the CCO peak of 886 cm^-1 of ethanol can be used to distinguish Sanjiu from brand Baijiu.