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…

Addition of glutathione-rich inactivated yeasts to white musts: effects on wine composition and sensory quality

Glutathione plays a key role in preventing some oxidative processes during winemaking. This molecule limits the must enzymatic oxidation, reacts with caffeic acid and generates a colourless compound that prevents subsequent browning. It also has a protective effect on wine aroma, preventing the oxidation of the volatile compounds with a high sensory impact.

Melatonin priming retards fungal decay in postharvest table grapes 

Postharvest losses of fruits may reach in some cases 40% in developed countries. This food waste has a significant carbon footprint and makes a major contribution toward greenhouse gas emissions so sustainable postharvest strategies are being investigated.
Melatonin, a well-known mammalian neurohormone, has been investigated as a priming agent to slow down fungal decay progression in postharvest climacteric and some non-climacteric fruits. However, the molecular and metabolic mechanisms responsible for such enhancement of disease tolerance are largely unknown.

Phenology and bioclimate of grapevine varieties in the tropical region of the São Francisco Valley, Brazil

La région de la Vallée du São Francisco, situe à 9º S, est en train d’augmenter la production des vins fins les dernières années. La région présente climat du type tropical semi-aride (climat viticole à variabilité intra-annuelle selon le Système CCM Géoviticole : “très chaud, à nuits chaudes et à sécheresse forte à sub-humide” en fonction

Frost risk projections in a changing climate are highly sensitive in time and space to frost modelling approaches

Late spring frost is a major challenge for various winegrowing regions across the world, its occurrence often leading to important yield losses and/or plant failure. Despite a significant increase in minimum temperatures worldwide, the spatial and temporal evolution of spring frost risk under a warmer climate remains largely uncertain. Recent projections of spring frost risk for viticulture in Europe throughout the 21st century show that its evolution strongly depends on the model approach used to simulate budburst. Furthermore, the frost damage modelling methods used in these projections are usually not assessed through comparison to field observations and/or frost damage reports.
The present study aims at comparing frost risk projections simulated using six spring frost models based on two approaches: a) models considering a fixed damage threshold after the predicted budburst date (e.g BRIN, Smoothed-Utah, Growing Degree Days, Fenovitis) and b) models considering a dynamic frost sensitivity threshold based on the predicted grapevine winter/spring dehardening process (e.g. Ferguson model). The capability of each model to simulate an actual frost event for the Vitis vinifera cv. Chadonnay B was previously assessed by comparing simulated cold thermal stress to reports of events with frost damage in Chablis, the northernmost winegrowing region of Burgundy. Models exhibited scores of κ > 0.65 when reproducing the frost/non-frost damage years and an accuracy ranging from 0.82 to 0.90.
Spring frost risk projections throughout the 21st century were performed for all winegrowing subregions of Bourgogne-Franche-Comté under two CMIP5 concentration pathways (4.5 and 8.5) using statistically downscaled 8×8 km daily air temperature and humidity of 13 climate models. Contrasting results with region-specific spring frost risk trends were observed. Three out of five models show a decrease in the frequency of frost years across the whole study area while the other two show an increase that is more or less pronounced depending on winegrowing subregion. Our findings indicate that the lack of accuracy in grapevine budburst and dehardening models makes climate projections of spring frost risk highly uncertain for grapevine cultivation regions.

Loose clustered vignoles clones reduce late season fruit rots

‘Vignoles’ is an aromatic, white-fruited wine grape variety valued by growers and wineries in the Eastern United States. Vignoles is grown in diverse locations in New York, Missouri, Indiana, Ohio, Pennsylvania, Illinois, Nebraska and Michigan. Consumers recognize and value the variety for its special wine quality.