光谱学与光谱分析, 2017, 37 (8): 2486, 网络出版: 2017-08-30  

二组分食用混合油的线性混合模型研究与应用

Research and Application of Linear Mixing Model of Two-Component Mixed Edible Oil
作者单位
1 天津大学精密仪器与光电子工程学院, 天津 300072
2 中国医学科学院生物医学工程研究所, 天津 300192
摘要
基于二组分混和食用油的吸收系数是各自组分吸收系数按照掺杂比例的线性组合的假设以及朗伯-比尔吸收机理, 提出并推导了二组分食用混合油的线性混合数学模型。 该数学模型可根据相同厚度的两种原料油和其二组分混合油对相同光源的吸收光强变化计算出混合油的组分比例。 根据误差理论, 利用全微分公式分析了组分比例计算值的误差, 表明通过选择使两种原料油的透射光强和吸光度差值的乘积较大的波长位置, 可以优选出检测波长。 搭建了可见-近红外光谱检测系统, 利用花生油掺杂玉米油、 花生油掺杂大豆油和玉米油掺杂大豆油三种混合油对模型进行了验证。 结果表明, 该模型对掺杂10%以上的混合油的成分比例计算值和实际值的相对误差在5%以内, 相关系数分别达到0.999 4, 0.999 7和0.999 3, 标准误差分别为0.006 9, 0.005 1和0.007 6, 并证实本研究的波长选取方法是合理的。 此外, 对3种按同样比例组合的、 未混合的分立油样本进行了检测, 计算组合比的相对误差也可控制在10%以内, 同时揭示入射光源的平行度和待测装置的垂直度对检测精度有一定影响。 试验证明, 不同于传统的光谱结合化学计量学的检测方法, 本方法可以仅通过检测原料油和混合油在选定波长上的吸收光强即可准确计算得到掺杂比例。
Abstract
A linear mixing model of the two-component mixed edible oil was proposed based on the assumption that the absorption coefficient of the two-component mixed edible oil can be obtained by the linear combination of absorption coefficients of two raw oils according to the mixing proportion. Based on the Lambert-Beer’s Law, a series of absorption equations of the incident light was constructed to describe variations of light intensity after the same source light respectively passing through the two raw oils and their proportional mixture with the same thickness. As a result, a formula was derived to calculate the mixing proportion of the two-component mixed edible oil, which was a new method to quantitatively analyze the proportion of adulterated edible oil. According to the theory of errors, the calculation difference of mixing proportion to the actual value was analyzed by the total differential methods, and the result demonstrated that there was an optimal wavelength where the products of the absorption light intensity of two raw oils and the difference value between their absorbance were larger, and less calculation difference could be obtained. A VIS/NIR spectral detection system was assembled and used to validate the mixing proportions of corn oil adulterated in peanut oil, soybean oil adulterated in peanut oil and soybean oil adulterated in corn oil. The results showed that the principle of choosing the optimal testing wavelength was correct, and the relative errors between calculation values and actual values were less than 5% for adulterating proportions above 10%(v/v), as well as the correlation coefficients were 0.999 4, 0.999 7 and 0.999 3 with RMS errors of 0.006 9, 0.005 1 and 0.007 6. The results proved that the proposed linear mixing model was practicable. The comparative experiments, which were operated on the stacked series of two separate oil samples with same mixing proportions, also verified the correctness of the linear mixing model and the method for choosing the testing wavelength. In addition, these comparative experiments revealed that the parallelism of light source and verticality of oil vessels were important to the detection accuracy of mixing proportion. This paper introduces a new method of detecting the mixing proportion of two-component mixed edible oil which differs from the traditional method of spectroscopy combined with chemometrics. In this method, the mixing proportion of two-component mixed edible oil can be precisely computed only after three times data collection of absorption spectra of the two raw oils and their mixture.

许洪, 明东, 李迎新, 綦宏志, 孙美秀, 杨基春. 二组分食用混合油的线性混合模型研究与应用[J]. 光谱学与光谱分析, 2017, 37(8): 2486. XU Hong, MING Dong, LI Ying-xin, QI Hong-zhi, SUN Mei-xiu, YANG Ji-chun. Research and Application of Linear Mixing Model of Two-Component Mixed Edible Oil[J]. Spectroscopy and Spectral Analysis, 2017, 37(8): 2486.

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