Rapid and Nondestructive Determination of origin, volatile oil, sanshoamides and crack rate in the ‘Sichuan Pepper’ Based on a Novel Portable Near Infrared Spectrometer

Abstract

Sichuan Pepper is an important economic crop in the poor areas of Midwestern China. The price paid for Sichuan Pepper depends principally on its aroma and taste, as well as its appearance. In this research, a novel portable near-infrared (NIR) spectrometer was used to fast detect the origin, the content of volatile oil and sanshoamides, and crack rate which related to the aroma, taste and appearance of Sichuan Pepper. By steam distillation, UV–vis spectrophotometry and sampling weighing, each sample (n = 274) from four different origins were determined for the contents of volatile oil and sanshoamides, and crack rate. The origin, the content of volatile oil and sanshoamides, and crack rate were determined by using Linear discriminant analysis (LDA) and Partial least squares (PLS) methods. LDA was used to distinguish the samples from different origins, and the result showed that the method seemed to be effective, with accuracy of calibration set and prediction set reached 91.3 % and 86.8 %, respectively. PLS was used to predict the contents of volatile oil and sanshoamides, and crack rate in Sichuan Pepper samples. Coefficient of determination of prediction (R2p) and root mean square errors of prediction (RMSEP) obtained were 0.839 and 0.378; 0.822 and 2.52; 0.826 and 6.60, for volatile oil, sanshoamides and crack rate, respectively. The results showed that the origin, the content of volatile oil and sanshoamides, and crack rate of Sichuan Pepper could be determined quickly, nondestructively and in real time by a portable NIR spectrometer.