Terroir 2004 banner
IVES 9 IVES Conference Series 9 Applications of Infrared Spectroscopy from laboratory to industry

Applications of Infrared Spectroscopy from laboratory to industry

Abstract

The grape and wine industries have long sought rapid, reliable and cost-effective methods to screen and monitor all the stages of the winemaking process, which include grape ripening in the vineyard, harvest and grape reception at the weighbridge, the fermentation stage and the bottling of the final product. Primary requirements of effective quality control in this environment would include the handling of complex sample matrices, a high degree of automation, precision, accuracy and where relevant, good agreement with the reference methods conventionally used for grape and wine analysis. Although conventional chemical methods still remain the workhorse of the wine analytical laboratory, some disadvantages such as lengthy assay times, unsuitability for automation, labour-intensive activities and the generation of large amounts of chemical waste, place an obstacle in their use for rapid quality control purposes.
Infrared (IR) spectroscopy is not a new application in the field of analytical chemistry. Recent improvements in IR instrumentation and the development of innovative and powerful software applications have optimised this technology. Currently, multi-component analytical instruments with impressive performance data in terms of simple sample handling, accuracy, precision and speed of analysis, are commercially available. The technology is based on the measurement of vibrational frequencies of covalent bonds in functional groups such as C-C, C-H, O-H, C=O and N-H, upon absorption of radiation in the IR region of the electromagnetic spectrum. Since IR spectroscopy is an indirect method employing empirical correlations between compositional and/or functional quality attributes and the IR spectra of samples, multivariate data analytical techniques are used to establish these correlations.
This presentation highlights the use of near infrared (700-2500 nm) and mid infrared (2500 – 5 x 104 nm) spectroscopy for quantitative and qualitative applications in the grape and wine industries. These include the measurement of colour, sugar and acidity in grapes, as well as the quantification of routine wine parameters such as pH, volatile acidity, titratable acidity, alcohol and sugar in wine. Industrial applications include the streaming of grape juice based on colour measurement. Future directions in IR spectroscopy regarding wine flavour analysis and product authentication are discussed.

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

H. Nieuwoudt (1) and F. Bauer (1)

(1) Institute for Wine Biotechnology, Department of Viticulture and Oenology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa

Contact the author

Tags

IVES Conference Series | Terroir 2004

Citation

Related articles…

Evaluation of physiological properties of grapevine clones of ‘Tempranillo’ and ‘Graciano’ in DOCa Rioja (Spain)

In order to avoid the loss of grapevine intra-varietal diversity of DOCa Rioja grape varieties, Regional Government of La Rioja established a germplasm bank with more than 1.600 accessions, whose origin lies in the prospecting and sampling of ancient vineyards located throughout the whole region. 30 clones of Tempranillo and 13 clones of Graciano were preselected and multiplied in a new vineyard for further observations. The aim of this work is to describe the first results from the physiological characterization by an optical sensor of these preselected clones, which constitute the base of a new clonal selection that aims to increase the range of available certified clones and to improve the adaptation of these varieties to future objectives and environmental conditions.

Influence of the type of tanks employed for winemaking on red wine phenolic composition

The grape maturation process is being affected by the consequences of global climate change and, as a result, there is a gap at harvest time between the technological maturity of grapes (mostly the concentration of sugar and acids) and its phenolic quality. Due to this gap, the wines elaborated using those grapes show a non-adequate phenolic composition, which results in defects on its color and astringency characteristics. Astringency is mainly related to the salivary protein precipitation because of the interaction not only with wine flavanols but also with other wine phenolics, such as flavonols or different pigments.

PROBING GRAPEVINE-BOTRYTIS CINEREA INTERACTION THROUGH MASS SPECTROMETRY IMAGING

Plants in their natural environment are in continuous interaction with large numbers of potentially pathogenic and beneficial microorganisms. Depending on the microbe, plants have evolved a variety of resistance mechanisms that can be constitutively expressed or induced. Phytoalexins, which are biocidal compounds of low to medium molecular weight synthesized by and accumulated in plants as a response to stress, take part in this intricate defense system.1,2
One of the limitations of our knowledge of phytoalexins is the difficulty of analyzing their spatial responsiveness occurring during plant- pathogen interactions under natural conditions.

Shoot positioning: effect on physiological, vegetative and reproductive parameters

[English version below]

On a étudié durant deux saisons de croissance (2002/2003 et 2003/2004) l’effet de l’orientation vertical des rameaux sur les paramètres physiologiques, végétatifs et reproductifs dans la région de Stellenbosch dans un vignoble du cépage Merlot sur 99 R conduite à espalier et taillé a cordon coursonné. Les vignes étaient espacées 2.7 x 1.5 m. L’irrigation a été appliquée quand la baie avait la dimension d’un pois et a la véraison.

Simulating the impact of climate change on viticultural systems in various European vineyards

Aim: Global climate change affects regional climates and hold implications for wine growing regions worldwide (Jones, 2007, 2015; van Leeuwen and Darriet, 2016). The prospect of 21st century climate change consequently is one of the major challenges facing the wine industry (Keller, 2010).