Determination of technological maturity of grapes and total phenolic compounds of grape skins in red and white cultivars during ripening by near infrared hyperspectral image: a preliminary approach.
Hyperspectral images of intact grapes during ripening were recorded using a near infrared hyperspectral imaging system (900-1700 nm). Spectral data have been correlated with grape skin total phenolic concentration, sugar concentration, titratable acidity and pH by modified partial least squares regression (MPLS) using a number of spectral pre-treatments and different sets of calibration. The obtained results (RSQ and SEP, respectively) for the global model of red and white grape samples were: 0.89 and 1.23 mg g(-1) of grape skin for total phenolic concentration, 0.99 and 1.37 °Brix for sugar concentration, 0.98 and 3.88 g L(-1) for titratable acidity and for pH 0.94 and 0.12. Moreover, separate calibration models for red and white grape samples were also developed. The obtained results present a good potential for a fast and reasonably inexpensive screening of these parameters in intact grapes and therefore, for a fast control of technological and phenolic maturity.
Food Colour & Quality Laboratory, Department of Nutrition & Food Science, Universidad de Sevilla, Facultad de Farmacia, 41012 Sevilla, Spain.
Julio
J
Nogales-Bueno
Food Colour & Quality Laboratory, Department of Nutrition & Food Science, Universidad de Sevilla, Facultad de Farmacia, 41012 Sevilla, Spain.
José Miguel
JM
Hernández-Hierro
Food Colour & Quality Laboratory, Department of Nutrition & Food Science, Universidad de Sevilla, Facultad de Farmacia, 41012 Sevilla, Spain.
Francisco José
FJ
Rodríguez-Pulido
Food Colour & Quality Laboratory, Department of Nutrition & Food Science, Universidad de Sevilla, Facultad de Farmacia, 41012 Sevilla, Spain. Electronic address: heredia@us.es.
Francisco José
FJ
Heredia
D005638:Fruit / Q000737:chemistry* / Q000145:classification / Q000254:growth & development; D010636:Phenols / Q000032:analysis*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D027843:Vitis / Q000737:chemistry / Q000145:classification / Q000254:growth & development*
D010636:Phenols
Chemometrics; Grapes; H; MPLS; MSC; Mahalanobis distance; NIRS; Near infrared hyperspectral imaging; PC; PCA; PLS; Phenolic maturity; RSQ; SEC; SECV; SEP; SNV; Technological maturity; coefficient of determination; modified partial least squares; multiplicative scatter correction; near infrared spectroscopy; partial least squares; principal component; principal component analysis; standard error of calibration; standard error of cross-validation; standard error of prediction; standard normal variate