VARIETIES, ORIGIN AND CHEMICAL COMPOSITION EVALUATION OF PERUVIAN CHILI PEPPERS USING NEAR INFRARED SPECTROSCOPY

Peru is considered as one of the countries with the largest number of Capsicum varieties in the world. Introduction of these varieties to the market requires the understanding of their chemical composition. Capsaicinoids, fatty acids, polyphenols, flavonoids and sugars are the most common chemical compounds found in peppers. These chemical parameters are currently evaluated by time consuming analytical techniques such as liquid and gas chromatography preceded by rigorous sample preparation. Although some works have reported the use of less or no destructive techniques such as near infrared spectroscopy (NIRS) on peppers samples, the big biodiversity of Peruvian peppers varieties by an infrared spectroscopical analysis have not yet been reported. In this work, samples of diverse varieties of Capsicum including different accessions of C. baccatum, C. chinense, and C. annum, cultured in three different Peruvian regions were analyzed by NIRS in order to evaluate the differences of samples by their geographical origin and/or varieties, as well as to quantify the content of their principal chemical components including fatty acids, flavonoids and capsaicinoids. Near infrared spectra were acquired by diffuse reflectance in the range of 12500 and 4000 cm-1 in a MPA Bruker NIR spectrometer. Chemometric analysis including principal component analysis (PCA) and partial least squares (PLS) were applied using Pirouette 4.5 software (Infometrix Inc). Results show samples grouping by varieties and origin and that total capsaicinoids, and some fatty acids (as linoleic and behenic acid) can be modeled by PLS models using diverse varieties trough of a global NIR model, with correlation coefficient greater than 0.9 and low standard error of calibration and prediction for the range of evaluated concentration. These results contribute to the rapid characterization of these varieties for potentially commercial uses in food, nutraceutic and pharmaceutical industries and could provide an efficient tool for differentiation of these peppers, prevention of frauds, guaranteeing their origin and future developing of classification models to identify species of some varieties not identified based on the spectroscopical patterns.