Indirect Determination of Liquor Alcohol Content Based on Near-Infrared Spectrophotometry
HU Yao-qiang1, 2, 3, GUO Min2, YE Xiu-shen2, LI Quan2, LIU Hai-ning2*, WU Zhi-jian2
1. College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang 524088, China
2. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Provincial Key Laboratory of Resources and Chemistry of Salt Lakes, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China
3. Key Laboratory of Climate, Resources and Environment in Continental Shelf Sea and Deep Sea of Department of Education of Guangdong Province, Guangdong Ocean University, Zhanjiang 524088, China
Abstract：Alcohol is a key technical indicator of liquor, a favorite of consumers as a daily drinking. A simple and fast detection method for ethanol in liquor can help to improve the efficiency of a liquor inspection. Spectroscopy with the advantages of rapid and non-destructive can provide help for the analysis of ethanol content. Based on the good absorption effect of water molecules on infrared light, this paper explored the feasibility of indirect analysis of ethanol content in liquor by near-infrared spectrophotometry. By studying the effect of the optical path on the UV-VIS-NIR absorption spectra of water and ethanol, it is found that water molecules have an independent absorption peak at 1 448 nm. This absorption peak has a mutational point under the optical path of 10 mm. However, when the optical path is reduced to 1 mm, the shape of the absorption peak becomes symmetric and smooth, bringing the possibility of quantitative analysis. The absorption peak of aqueous ethanol solution in the range of 1 000~1 800 nm regularly decreases with the increase of ethanol content. It shows that the force between ethanol and water molecules do not affect their absorption spectrum. The linear equation between absorbance and alcohol content is obtained: A=1.38-0.013m% (R2=0.996 7) by extracting the absorbance at 1 448 nm. However, the fitting effect has a large relative deviation when the alcohol content is lower than 20% or higher than 80%. A better linear fitting equation with an excellent fitting effect is obtained: A=1.40-0.014m% (R2=0.999 3) after adjusting the fitting range to 20%~80%. The reliability of this method was tested through some purchased bulk and brand liquors. The results obtained by this method show a small relative deviation with the alcohol content marked on brand bottles, which is within the allowable error range of absorption spectrum analysis. Moreover, there are large relative deviations in the test measurement results of part of bulk liquors, which may be caused by the weaker quality control of bulk liquor. To some extent, this method has good accuracy and precision in detecting the alcohol content of liquor. This method has the advantages of convenience, rapid, no auxiliary reagent and wide linear range. It can be used as a test method for quickly analyzing the alcohol content of liquor.
胡耀强，郭 敏，叶秀深，李 权，刘海宁，吴志坚. 近红外光谱法间接测定白酒酒精度[J]. 光谱学与光谱分析, 2022, 42(02): 410-414.
HU Yao-qiang, GUO Min, YE Xiu-shen, LI Quan, LIU Hai-ning, WU Zhi-jian. Indirect Determination of Liquor Alcohol Content Based on Near-Infrared Spectrophotometry. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(02): 410-414.
[1] Song X B, Zhu L, Wang X L, et al. Food Chemistry, 2019, 297: 124959.
[2] Fang C, Du H, Jia W, et al. Metabolites, 2019, 9(1): 1.
[3] Hu H C, Zeng T, Zhang S K, et al. Holzforschung, 2018, 72(11): 973.
[4] Chen S, Sha S, Qian M, et al. Journal of Food Science, 2017, 82(12): 2816.
[5] ZHAO Zhe, WANG Hui, WANG Hui-quan, et al(赵 喆，王 慧，王慧泉，等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2019, 39(4): 1070.
[6] Shan R F, Chen Y, Meng L C, et al. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2020, 224: 117455.
[7] Dong Q, Yu C, Li L, et al. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019, 22(5): 117183.
[8] Mahajan P G, Dige N C, Vanjare B D, et al. Journal of Molecular Structure, 2019, 1198: 126915.
[9] Khopkar S, Shankarling G. Dyes and Pigments, 2019, 170: 107645.
[10] Mohamed S H, Issa Y M, Elfeky S A. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019, 222: 117186.
[11] Mahmood A. Solar Energy, 2016, 123: 127.
[12] Ho C L, Wong W Y. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 2016, 28: 138.
[13] Dong W, Guo R N, Liu M, et al. Food Research International, 2019, 125: 108546.
[14] Yu H Y, Xie T, Xie J R, et al. Food Chemistry, 2019, 293: 8.
[15] Zheng J, Zhao D, Peng Z F, et al. Food Research International, 2018, 114: 64.
