Total anthocyanin content determination in intact açaي (Euterpe oleracea Mart.) and palmitero-juçara (Euterpe edulis Mart.) fruit using near infrared spectroscopy (NIR) and multivariate calibration

The aim of this study was to evaluate near-infrared reflectance spectroscopy (NIR), and multivariate calibration potential as a rapid method to determinate anthocyanin content in intact fruit (açaí and palmitero-juçara). Several multivariate calibration techniques, including partial least squares (PLS), interval partial least squares, genetic algorithm, successive projections algorithm, and net analyte signal were compared and validated by establishing figures of merit. Suitable results were obtained with the PLS model (four latent variables and 5-point smoothing) with a detection limit of 6.2 g kg−1, limit of quantification of 20.7 g kg−1, accuracy estimated as root mean square error of prediction of 4.8 g kg−1, mean selectivity of 0.79 g kg−1, sensitivity of 5.04 × 10−3 g kg−1, precision of 27.8 g kg−1, and signal-to-noise ratio of 1.04 × 10−3 g kg−1. These results suggest NIR spectroscopy and multivariate calibration can be effectively used to determine anthocyanin content in intact açaí and palmitero-juçara fruit.