Rapid Assessment of Total Phenolic and Anthocyanin Contents in Grape Juice Using Infrared Spectroscopy and Multivariate Calibration

Grape juice is rich in bioactive compounds that are known for beneficial effects, such as prevention of cancer and diabetes. The determination of the content of these compounds has been carried out following several protocols which generated toxic waste. In this context, infrared spectroscopy in near (NIR) and mid- (MIR) regions were applied for the determination of total phenolic and anthocyanin content (TPC and TAC, respectively) in grape juice for being a rapid green methodology. Calibration models were built using partial least squares regression (PLSR) to predict TPC and TAC in grape juice. MIR and NIR had a similar satisfactory performance to predict TAC presenting low RMSEP (4.22 mg/100 mL and 4.44 mg/100 mL). In TPC prediction, MIR presented a RMSEP (0.21 mg GAE/mL) slightly better in comparison to the one presented by NIR (0.37 mg GAE/mL). Errors can be considered acceptable for the determination of TPC and TAC in grape juice, qualifying both infrared techniques to replace traditional wet methodologies, with the advantage of being environmentally friendly.