Application of Two-Dimensional Correlation Spectra in the Identification of Adulterated Rice
LIU Ya-chao1, LI Yong-yu1*, PENG Yan-kun1, YAN Shuai1, WANG Qi1, HAN Dong-hai2
1. College of Engineering,China Agricultural University, National Research and Development Center for Agro-processing Equipment, Beijing 100083, China
2. College of Food Science & Nutritional Engineering, China Agricultural University, Beijing 100083, China
Abstract:With the improvement of economic level, people have higher and higher requirements on the quality of rice. Due to the large price difference among different rice varieties, many traders seek profits by filling the inferior with the superior, sometimes the adulteration ratio is as high as 30%, which seriously damages the interests of consumers. Rice as a carbohydrate, which cannot be distinguished from adulterated rice by one-dimensional near-infrared spectroscopy. At present, many kinds researches focus on the establishment of stoichiometric discrimination model based on one-dimensional spectrum. Two-dimensional correlation spectra have the advantages of high resolution, and the attribution of analytical peaks and the effective information hidden in the one-dimensional spectrum of adulterated rice can be further explored. This paper takes Wuchang rice as the research object, selects six kinds of rice which are difficult to be distinguished by the naked eye as the adulterated rice, and prepares 140 rice samples with a different adulterated proportion of 5% to 50% respectively. The mean spectrum of Wuchang rice was taken as the reference spectrum and the mixing ratio as the external disturbance factor, the NIR spectra of adulterated and Wuchang rice were calculated with the reference spectrum. By analyzing the characteristics of Two-dimensional correlated synchronous spectra of rice with different mixing ratios, it was found that the cross peak intensity of auto-correlation spectra at 1 420 and 1 920 nm and synchronous spectra at (1 420,1 920) and (1 920, 1 420) nm increased with the increase of adulteration ratio, and the 1 920 nm automatic peak has the most significant response to the adulteration ratio. By tracing the generation mechanism of two automatic peaks at 1 420 and 1 920 nm of the autocorrelation spectrum and analyzing the attribution of corresponding functional groups, it was found that the response degree of amylose in rice to the adulteration ratio was higher than that of protein and other carbohydrates. The maximum value of the automatic peak at 1 420 and 1 920 nm and the maximum value of the cross peak at (1 920,1 420) nm in the Wuchang rice synchronous spectrum were used as the discriminant threshold to discriminate 140 rice samples. The results showed that the best discriminant accuracy was 93.3% based on the 1920nm automatic peak value, and the discriminant accuracy was 100% for the adulterated rice samples with the adulterated ratio of 20% or more, As the adulterated ratio to reduce the discriminant accuracy also gradually decline, with 15%, 10%, 5% sample discriminant accuracy were 91.7%, 66% and 75% respectively. To sum up, the blending ratio as the external interference factor and the characteristics of the two-dimensional synchronous spectrum of rice with different adulteration ratios were analyzed, the adulterated rice can be distinguished simply and effectively by the difference of characteristic peak value, compared with previous NIR discriminant models, it is not necessary to prepare a large number of samples to train the model, which provides a new idea for the rapid identification of adulterated rice.
刘亚超,李永玉,彭彦昆,闫 帅,王 绮,韩东海. 近红外二维相关光谱的掺和大米判别[J]. 光谱学与光谱分析, 2020, 40(05): 1559-1564.
LIU Ya-chao, LI Yong-yu, PENG Yan-kun, YAN Shuai, WANG Qi, HAN Dong-hai. Application of Two-Dimensional Correlation Spectra in the Identification of Adulterated Rice. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(05): 1559-1564.
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