拉曼光谱检测技术具有快速、 高效、 无需样品预处理和非接触检测等独特优势, 是实现大批量样品高通量无损在线检测的理想方法, 同时也是实现白酒产品中乙醇浓度快速筛检的适宜手段。 然而与纯水溶液不同, 在激发光激励下大部分白酒的光谱中除了乙醇和水的拉曼特征峰外, 还存在明显的本底荧光干扰, 给酒精度检测精度带来负面影响。 因此, 基于拉曼特征峰峰强比值法检测乙醇浓度, 在进行数据处理前需人为选取进行荧光本底拟合的数据点, 主观性强, 数据处理效率低, 难以充分满足高通量样品在线筛检的技术需求。 针对上述问题, 基于自主搭建的激光偏振拉曼光谱检测系统, 对不同偏振角度线偏振光激发下四种白酒样品的拉曼特征峰和荧光本底干扰的偏振特性开展了详细研究, 并根据二者间的偏振特征差异提出了偏振拉曼光谱辅助的白酒乙醇浓度快速检测方法。 实验结果表明, 在差分偏振拉曼光谱的辅助下, 三次多项式拟合的相关系数超过0.99, 可实现3%~97%vol范围内乙醇浓度的准确反演, 且四种白酒样品乙醇浓度的反演精度明显高于传统方法, 显著提升了白酒酒精度检测的效率和精度。

Due to its unique advantages of rapid, high efficiency, non-contact detection and no need for sample pretreatment, Raman spectroscopy is an ideal method for high-throughput, non-destructive on-line detection of large quantities of samples and a suitable method for rapid detection of ethanol concentration of liquor products. However, different from pure water, besides Raman characteristic peaks of ethanol and water, there is apparent fluorescence interference within the spectra of most liquor under laser excitation, which negatively influences the quantitative determination of ethanol concentration. Therefore, during the determination of ethanol concentration based on the Raman characteristic peak intensity ratio method, the data points for fluorescence background fitting need to be manually selected before data processing, which possess strong subjectivity and low data processing efficiency and is difficult to fully meet the technical requirements of the high-throughput samples on-line screening. In order to solve the above problems, based on the self-built laser-induced polarized Raman spectroscopy detection system, a series of experiments were carried out on the polarization characteristics of the Raman peaks and fluorescence background of four kinds of liquor samples under excitation of linearly polarized laser with different polarization orientation. Based on the polarization difference of them, a quantitative determination method of alcohol concentration in liquor products based on polarized Raman spectroscopy is proposed. The experimental results show that, with the aid of differential polarization Raman spectroscopy, the correlation coefficient of the polynomial fitting of three times is over 0.99, which can achieve accurate inversion of ethanol concentration in the range of 3%~97%vol. The accuracy of ethanol concentration in four kinds of liquor samples is significantly higher than the inversion results of traditional methods, which significantly improves the accuracy and efficiency of alcohol concentration determination of liquor products.