The Research On Rapid Detection Of The Main Components And Freshness Of Rice By Near Infrared Spectroscopy

Near infrared spectroscopy,which as a rapid detection technology has been deeply studied by scholars from various countries. The near infrared spectroscopy mainly produced by molecular vibration frequency within the group absorption and frequency absorption harmony, and only hydrogen-containing functional groups such as C-H, N-H, S-H, and O-H' stretching vibration can be detected. Near infrared spectroscopy analytical technique has its own advantages,such as rapid analysis of high efficiency and low cost and because of them, the Near-infrared technology has been widely used in agricultural, food, biological sciences, chemical mining and other fields now. Rice is an important strategic materials and an vital guarantee for maintaining people's lives, their quality control related to people's livelihood. However, in recent years, there are some sharpshooters who were posing old rice as the new rice into marketing, this has serious impact on the normal circulation of rice and the public food safety. Therefore, rapid detection of near infrared spectroscopy technology in rice freshness and quality testing has important practical significance.In this paper, there are 30 different fresh early season rice which place of origins are Changde and Yiyang have been used in the research and the amylose and fatty acid content has been used as the index to study the variance of rice samples' quality during storage and near infrared spectroscopy technique has been used for the detection of rice samples' quantitative and qualitative research. Under the conditions of artificial aging, all the rice samples' fatty acid and amylose content increased in varying degrees, fatty acid in rice changed significantly different which increased in the rang of 5.39-19.77mg/100g; amylose content in rice changed less significantly different which increased in range of 1.34%-6.66%. In the comparison of rice sample in different freshness:the average increase in fatty acid of rice shows that the 07 rice samples' growth were highest(15.13mg/100g), the 09 rice samples' growth were higher (10.54mg/100g) and the 08 rice samples' increase in the minimum(6.40mg/100g);the average increase in amylose content of rice shows that the 09 rice samples' growth were highest(4.42%), the 08 rice samples' growth were higher(2.81%) and the 07 rice samples'increase in the minimum(2.33%).PLS quantitative model for rice freshness has been established.Different region pretreatment methods for spectrum model were compared.The model's optimal coefficients were:fatty acids:the full spectrum wavelength region+first derivative+ Norris smoothing; then the fatty acid model correlation coefficient r, Root mean Square Error of Calibration(RMSEC), Root mean Square Error of Cross-Validation (RMSECV) were 0.85934,1.78,2.35; Amylose content:the full spectrum wavelength region+first derivative+multiplicative scatter correction+Norris smoothing,then the correlation coefficient r, Root mean Square Error of Calibration(RMSEC), Root mean Square Error of Cross-Validation(RMSECV) were 0.92775,1.49,1.65.This paper also studied the construction of discriminant analysis modef for qualitative analysis of rice freshness by using NIRS and Principle Component Analysis(PCA)-Mahalanobis Distance.The optimal model coefficients were:the full spectrum wavelength region+multiplicative scatter correction, the optimal main component was 10,At this point the model had the highest rates of discrimination which can reach 96.7%.The results show that:using near infrared spectroscopy technique for detection of rice basis and freshness is possible.