Use of near infrared hyperspectral tools for the screening of extractable polyphenols in red grape skins

•Extractable polyphenols from red grape skin have been studied.•Methodology for recording and processing hyperspectral images has been applied.•Calibration models have been developed from reference and hyperspectral data.•These models present a good potential for a fast screening of these parameters.•The heterogeneity of these parameters within the ripeness stage has been evaluated. Hyperspectral images of intact grapes were recorded at harvest time using a near infrared hyperspectral imaging system (900–1700nm). Spectral data have been correlated with red grape skin extractable polyphenols (total phenolic, anthocyanins and flavanols) by modified partial least squares regression (MPLS) using a number of spectral pretreatments. The obtained results (coefficient of determination (RSQ) and standard error of prediction (SEP), respectively) for the developed models were: 0.82 and 0.92mgg−1 of grape skin for extractable total phenolic content, 0.79 and 0.63mgg−1 of grape skin for extractable anthocyanin content, 0.82 and 0.45mgg−1 of grape skin for extractable flavanol content. The obtained results present a good potential for a fast and reasonably inexpensive screening of the extractable polyphenolic compounds in intact grapes. Moreover, the heterogeneity of extractable polyphenols within the ripeness stage has been also evaluated using the proposed method.