Shortwave near infrared spectroscopy for non-destructive determination of maturity of wine grapes

Abstract

Near-infrared (NIR) spectroscopy has become a very popular technique for the non-invasive assessment of intact fruit. This work presents an application of a low-cost commercially available NIR spectrometer for the estimation of ripeness of Chilean wine grapes. Two configurations for the spectra acquisition were used (diffuse transmittance and interactance), using a custom-designed contact probe. Samples of Chardonnay, Carménère and Cabernet Sauvignon, collected over the 2002 harvest and pre-harvest seasons, were analysed for total soluble solids content ( • Brix). Partial least squares calibration models, obtained from several preprocessing techniques (smoothing, multiplicative signal correction, standard normal variate, etc), were compared. Also, two spectral regions were used, one without the red part of the visible spectrum (just the short-wave (SW-NIR) region) and the other including it. Performance of different models was assessed in terms of root mean square of cross-validation, root mean square of prediction (RMSEP) and R 2 for a validation set of samples. RMSEPs of 1.06 with R 2 = 0.942 indicate that it is possible to estimate wine grape ripeness ( • Brix value), by using a CCD portable spectrometer. The red grape models performed better than the white grape models.

Identification and quantification of furanic compounds in tequila and mezcal using spectroscopy and chemometric methods

“…Some works have shown the effectiveness of applying chemometric methods to different spectroscopic techniques. For example, NIR and Mid-IR spectra to estimate the ripeness of wine grapes and discrimination of Cognacs, 16,17 and to FT-IR, UV and fluorescence spectra for the characterization and classification of wine and brandies [18][19][20] or the determination of several compounds such as sugars, 21,22 dyes 23 and stimulants 24 in drinks. For the case of tequila, chromatic analysis and chemometrics tools have been applied to FT-IR and UV-Vis absorption spectra to discriminate between 100% agave and mixed tequilas as well as among tequilas from different brands.…”

Preliminary Results on the Non-Destructive Determination of Pear (Pyrus Communis L.) Cv. Rocha Ripeness by Visible/Near Infrared Reflectance Spectroscopy

“…This ratio was not easily related to any of the ripening parameters determined (Table 1), although this region is expected to be affected by the SSC and % dry matter, due to water and the carbohydrates absorbance region (McGlone and Kawano, 1998). In contrast to other fruits such as apple and grapes (Ventura et al, 1998;Zude-Sasse et al, 2002;Herrera et al, 2003), the spectra obtained and the corresponding ratios could hardly be related to the °Brix, since this parameter was unaltered along ripening.…”

“…The advantage of Vis/NIRS includes fast execution, limited sample pre-processing and easy use in process control and grading systems. Indeed, it has been used to assess quality attributes such as acidity, juiciness, sugar content, firmness, texture parameters, pigments content and starch degradation in a large variety of horticultural products, namely, peach, nectarine, kiwifruit, melon, mandarin, pineapple, grape, papaw and mango (Kawano et al, 1992;Guthrie and Walsh, 1997;Guthrie et al, 1998;Lammertyn et al, 1998;McGlone and Kwano, 1998;Ventura et al, 1998;Greensill and Newman, 1999;Zude-Sasse et al, 2002;Herrera et al, 2003;Solovchenko et al, 2005).…”

Optimisation of the Quantification of Total Soluble Solids, pH and Titratable Acidity in South African Grape Must using Fourier Transform Mid-infrared Spectroscopy

“…In contrast to wine analysis, spectroscopic applications for grape analysis have mostly focussed on the use of visible and near-infrared spectroscopy (Manley et al, 2001;Jarén et al, 2001;Dambergs et al, 2003;Herrera et al, 2003;Arana et al, 2005), and the evaluation of FT-MIR spectroscopy for comprehensive grape analysis has only been reported in a very limited number of publications (Dubernet et al, 2000). Furthermore, the prediction accuracies of the global calibrations, when used for the quantification of grape samples from non-European origin, have not been evaluated thoroughly.…”