Quantification of soluble solids in reconstituted acai (Euterpe oleracea Mart.) pulp using near-infrared spectroscopy

Acai consumption is increasing worldwide because of the growing recognition of its nutritional and therapeutic properties. This product is classified based on its soluble solids content (SS), but the determination of SS in pulp is time consuming, tedious and not suitable for modern food processing plants. As near-infrared (NIR) systems have been implemented to measure various quality attributes of food products, the objective of this study was to evaluate the feasibility of NIR diffuse reflectance spectroscopy to quantify the SS content of acai pulp. Partial least squares (PLS) regression models were constructed to predict the SS. An optimum PLS model required one latent variable [principal component (PC)1=97%] with a root-mean-square error of calibration (RMSEC) of 1.06% for the calibration data set and the root-mean-square error of prediction (RMSEP) of 1.03% for internal cross-validation. External validation using an independent data set showed good performance (RMSEP=1.33% and Rp(2)=0.82). NIR spectroscopy is a reliable method with which to determine SS in acai pulp and thereby to classify acai pulp according to established minimum quality standards.