【作者】 张帆；

【导师】 刘文军；

【作者基本信息】 哈尔滨工业大学 ， 物理学， 2018， 硕士

【摘要】 近年来,随着人们生活水平的不断提高,食品安全备受重视,食品安全检测方法也受到越来越多的关注。本文将生活中常见的白酒、地表水和食用油作为主要研究目标,在食品检测方面进行研究。本文基于自主研发的405nm激发波长的便携式光谱仪,采用拉曼光谱和荧光光谱分别研究了白酒中酒精含量,水中总氮含量以及食用大豆油的光谱特性。论文研究并总结了国内外食品检测技术发展的现状,并对目前几种典型的小型光谱仪进行简要介绍。同时,本文通过对荧光光谱和拉曼光谱原理的研究分析,探究了两种光谱的特征及应用。根据研究结果,本文决定利用拉曼光谱结合荧光光谱的方法进行具体的实验分析。首先,实验利用了乙醇和水分子的拉曼光谱特征实现了酒精含量的定量检测。通过对20%~100%不同浓度乙醇—纯水溶液的激光诱导拉曼光谱的检测,建立了乙醇和水的拉曼峰值比与乙醇浓度的对应关系,确定了线性拟合方程。同时,背景扣除算法有效降低了样品拉曼光谱中的荧光背景干扰,实现了对酒精度的定量检测。其次,对于水体总氮含量的研究,本文采用了传统的碱性过硫酸钾紫外分光光度法对采集的地表水样品进行了总氮含量的检测,结合DOM各组分的荧光光谱特征,确定了总氮含量与荧光特征峰的对应关系,通过对荧光光谱峰值强度与总氮含量值拟合得到的线性拟合方程,实现了水体总氮含量的定量检测。最后,为了进一步拓展小型便携式激光光谱仪的应用,本文对食用大豆油进行了实验分析。基于对食用大豆油的荧光光谱特性的理论分析,本文利用小型便携式光谱仪建立了三维荧光光谱检测系统,并对食用大豆油样品进行了三维荧光光谱检测,得到了信息更为全面的三维荧光光谱,发现了两个特征荧光峰,随后,同样利用小型便携式激光光谱仪对大豆油样品进行了二维激光诱导荧光光谱检测,分别测量了加热不同时间(10分钟,15分钟,20分钟,25分钟)的同一品牌大豆油样品的激发诱导荧光光谱,确定了荧光特征峰与样品加热时间的对应关系,实验结果表明荧光光谱中的第一特征峰强度整体呈增长趋势,第二特征峰呈持续下降趋势。本文对加热过程中可能发生的物质组成变化进行了研究分析,判断大豆油在此过程中可能产生的有害物质,为针对大豆油样品的质量检测提供依据。更多还原

【Abstract】 In recent years,as people’s living standards have been increasing,the field of food safety has attracted much attention.Food safety testing methods have also received more and more attention.In this thesis,liquor,water and edible oil,which are common in life,are studied as the main research targets in food detection.Based on portable spectrometer with 405 nm excitation wavelength,the alcohol content of liquor,the total nitrogen content of water and the spectral characteristics of edible soybean oil are studied by using Raman spectroscopy and fluorescence spectroscopy.The current status of international and domestic development are summarized,and several typical miniature spectrometers are briefly introduced.And several typical small-scale spectrometer are briefly introduced.At the same time,the characteristics and applications of fluorescence spectrum and Raman spectrum are studied.According to the results of this study,this paper decided to use Raman spectroscopy combined with fluorescence spectra are specific experimental analysis.First of all,the experiment uses the Raman spectra characteristics of ethanol and water molecules to realize the quantitative detection of alcohol content.By different concentration ethanol-water solution(20% ~ 100%)of laser induced Raman spectrum detection,has established the ethanol and water Raman peak ratio,the corresponding relationship between the concentration of ethanol to determine the linear fitting equation.At the same time,the background subtraction algorithm effectively reduces the fluorescence background interference in the sample Raman spectrum and realizes the quantitative detection of alcohol accuracy.Secondly,the thesis adopts the traditional alkaline potassium persulfate uv spectrophotometry for total nitrogen content in water samples.According to the fluorescence spectral characteristics of the DOM components,the content of total nitrogen and the corresponding relationship of the fluorescence characteristic peak is determined.By means of fluorescence spectrum peak intensity and total nitrogen content value fitting linear fitting equation,the thesis implements the total nitrogen content of quantitative detection of water.Finally,in order to further expand the application of portable laser spectrometer,the thesis makes an experimental analysis of edible soybean oil.Based on the fluorescence spectral characteristics of edible soybean oil of theoretical analysis.Three-dimensional fluorescence spectrum detection system is established by using portable spectrometer,and the three dimensional fluorescence spectrum edible soybean oil samples test obtains three-dimensional fluorescence spectrum with more comprehensive information and finds two characteristic fluorescence peak,then,the laser induced fluorescence spectrum detections using the same portable laser spectrometer for soybean oil samples of being measured for different heating time(10 minutes,15 minutes,20 minutes,25 minutes)of the same brand of soybean oil sample are induced,and the corresponding relationship of the fluorescence characteristic peaks of heating time to the sample is determines.The experimental results show that the first fluorescence spectrum characteristic peak intensity growth trend on the whole,the second characteristic peak keeps to decline,and the material composition changes may occur in the process of heating are analyzed.The soybean oil potentially harmful substances in the process is judged,and the basis for quality testing for soybean oil sample is provided.更多还原