Hyperspectral imaging of wine grapes and quality parameters analysed one by one on each berry.
Data correspond to the spectra in the NIR region of 7 wine grape varieties, collected in France at harvest time, chosen by the vintners and to all quality parameters analysed.
Vintages 2019 and 2020.
Spectra were recorded on fresh grapes at 20°C, after being washed and dried.
The acquisition system was composed by an hyperspectral imaging camera (Pika L, Resonon, Bozeman, MT, USA) coupled with an objective lenses (Xenoplan 1.4/23, Schneider-Kreuznach, Bad Kreuznach, Germany), a four 35W quartz tungsten halogen (QTH) MR16 35 W lamps adjusted at angle of 45° to illuminate the camera’s field of view, a mounting tower; and a transport stage (PS-12-20-1.0, Servo Systems Co., USA), with motor (DMX-J-SA-17, Arcus Technology Inc., Livermore, CA, USA). The sensor has 900 spatial channels each with 281 spectral channels covering the range from 400 to 1000 nm.
The height between the lens and the sample was set as 54 cm; the speed of the conveyer was set at 11 mm/s to ensure the same spatial shape of samples in the image and the exposure time was set at 12 ms with a gain of 10. The spectral resolution was 2.1 nm. Spectra were recorded from 387 to 1026 nm in a dark room where only the halogen light source was used. The berries reflectance measurement was made in the equatorial position of the berry. Twenty berries were analyses at the same time, but the region of interest (ROI) was defined per berry and an average spectrum was calculated according to this ROI.
Vines were conducted in simple Guyot, except the Grolleau blanc in Cordon de Royat.
Total Phenolic Index (TPI) was assessed by the absorbance at 280 nm, corrected by the potantial dilution.
Extractible and total phneolics and anthocyanins were analyzed as reported by Corona et al. 2015, Food Chemistry, 172.
Glucose, Fructose, malic and tartaric acids were analyzed by Gallery kits (Themo FischerScientific). TSS were analyzed by a portable refractometer Mettler Toledo Refracto 30PX.
The color intensity was calculated by CI = Abs 420 nm + Abs 520 nm + Abs 620 nm.