In-field spectrophotometric measurement to estimate maturity stage of wine grapes

P. Menesatti

doi:10.1117/12.735547

22 October 2007 In-field spectrophotometric measurement to estimate maturity stage of wine grapes

P. Menesatti

Proceedings Volume 6761, Optics for Natural Resources, Agriculture, and Foods II; 676118 (2007) https://doi.org/10.1117/12.735547
Event: Optics East, 2007, Boston, MA, United States

Abstract

High quality standards in modern wine production strictly depend of the choice of optimal maturity stage of grapes for the wine-making. Different chemical parameters of grape juice and peel were usually analysed in order to establish the optimal time of harvest. Aim of the study was to test the capability of a spectrophotometric visible and near-infrared (VIS-Nir) portable non-destructive system, to estimate chemical parameters to establish the optimal harvesting period. Spectral acquisition on wine grapes were made at three times before harvesting (18, 15, 9 days) and at the harvest for three different cultivars: Cabernet Sauvignon, San Giovese, Merlot. Trials were conducted in a vineyard located in South Tuscany, typical production area of Morellino di Scansano wine (Marchesi de' Frescobaldi producer). A VIS-Nir spectrometer - wavelength range 400 - 1000 nm, 3 nm bandwidth - equipped with a reflectance optical fiber probe (4 mm diameter) was used to estimate reductant sugars, total acidity, pH, potential anthocyanins and maturity index (sugar/acidity ratio) in whole wine grapes. A partial least square regression was performed for the different sampling times, including more than 3000 spectral measurements. Estimation of chemical parameters were performed with different standard error of prevision (SEP) and correlation coefficient (R): near to SEP=10% in respect to the average of the observed value and R=70%. Results showed that VIS-NIR reflectance was a suitable non-destructive method for monitoring the wine grapes maturity stage.

Citation Download Citation

P. Menesatti "In-field spectrophotometric measurement to estimate maturity stage of wine grapes", Proc. SPIE 6761, Optics for Natural Resources, Agriculture, and Foods II, 676118 (22 October 2007); https://doi.org/10.1117/12.735547

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