Determination of total phenolic compounds in yerba mate (Ilex paraguariensis) combining near infrared spectroscopy (NIR) and multivariate analysis

Abstract A quick method to determine the content of phenolic compounds (TPC) in yerba mate based on near infrared spectroscopy (NIR) was studied aiming to provide reductions of cost and analysis time for the mate industry without generating laboratory effluents. A total of 111 samples of yerba mate from different regions of the State of Parana, Brazil (Southeast, South Central and Metropolitan Area of Curitiba) was analyzed by the Folin-Ciocalteu method. The average contents of TPC found were 84.82, 133.31 and 37.00 mg g −1 , respectively. The samples were separated into three groups (regarding the different growing regions) using the principal component analysis (PCA). Models were developed using partial least squares (PLS) and some preprocessing strategies of the spectral data were evaluated. The best result was obtained by Multiplicative Scatter Correction (MSC) and first derivative with six latent variables. The best model presented a correlation coefficient of 0.81 with a prediction error of 12%. The results showed that NIR can be applied as an efficient method for the assessment of TPC, which allows classifying samples in relation to its origin of planting, processing and agronomic practices applied, aiding the decision of referral and use of yerba mate in different final products.