Concord grape juice is associated with many health benefits, and so it can be sold at a premium price. However, there is currently no method to verify the percent composition of Concord grape juice in grape juice blends. In order to guard against potential adulteration, a rapid method for authentication is required. Fourier Transform infrared (FT-IR) spectroscopy was used to develop a model which predicts the percent composition of Concord grape juice. The model was based on a training set of 64 samples with Concord concentrations ranging from 50% to 100%. Data was collected on an external validation set with a standard error of prediction of 5.6% using 7 factors. The results suggest the feasibility of using FT-IR coupled with chemometrics as a production-scale tool for authentication claims of Concord in grape juice blends, protecting consumers and businesses against deceptive labelling. © 2013 Published by Elsevier Ltd.