IVAS 2022 banner
IVES 9 IVES Conference Series 9 IVAS 9 IVAS 2022 9 Infrared spectroscopy investigation of fresh grapevine organs for clustering and classification.

Infrared spectroscopy investigation of fresh grapevine organs for clustering and classification.

Abstract

The spectral information acquired from fresh whole grapevine organs have yet to be fully explored. Infrared spectroscopy provides the means to rapidly measure fresh plant material and providing extensive information on the physical and chemical structure of samples. This study aimed to explore the spectra of fresh grapevine shoots, leaves, and berries throughout the growing season for clustering and classification. Sampling was performed across two vintages (2019-2020; 2020-2021) from November to March. Five locations, seven cultivars, and 17 commercial vineyards were included. Collection of whole shoots, including leaves and grape bunches, were performed on a monthly basis. The fresh grapevine organs were analysed using three spectroscopy methods within 24-36 hours of sampling. Mid-infrared (MIR) and near-infrared (NIR), making use of a solid probe (NIR-SP) and a rotating sphere (NIR-RS), were investigated. The raw spectra were firstly investigated using principal component analysis (PCA) followed by a more novel chemometric approach, unsupervised
self-organising maps (SOM). PCA as well as unsupervised SOM showed the most considerable grouping based on organ type. Additionally, the unsupervised SOM showed separation trends based on phenological stage. Investigation of the datasets per organ with SOM showed separation based on the phenological stage for berries and shoots, as well as shoots clustering based on lignification. Supervised SOM were examined for classification based on the observed clustering per organ type, phenological stage, and lignification. The accurate prediction of organ at 90.3% was possible for the NIR-SP dataset for 2019-2021. Overlapping of various phenological stages were seen for the grape berry datasets, but prediction improved to 85.6% for the NIR-RS 2019-2021 dataset when certain phenological
stages were grouped together. Accurate predictions of lignified and unlignified shoots were also seen for the NIR-SP 2019-2021 and NIR-RS 2020-2021 datasets at 74.4% and 89.9% respectively. The possibility of using spectral variable selection to improve the supervised SOM predictions were explored and promising results obtained for certain datasets. Following variable selection with OPLS-DA and S-plots, the prediction of shoots and leaves improved by 14% for the NIR-RS 2020-2021 dataset. The prediction of lignified and unlignified shoots improved considerably to 92.3% for the NIR-SP 2019-2021 dataset and 95.9% for the NIR-RS 2020-2021 dataset. This study showed the extensive information available in infrared spectra of fresh grapevine organs and how the information could be used to achieve important clustering and classifications objectives

DOI:

Publication date: June 23, 2022

Issue: IVAS 2022

Type: Article

Authors

Van Wyngaard Elizma¹, Blancquaert Erna¹, Nieuwoudt Hélène¹and Aleixandre-Tudo Jose Luis1,²

¹South African Grape and Wine Research Institute (SAGWRI), Department of Viticulture and Oenology, Stellenbosch University, Stellenbosch, South Africa
²Instituto de Ingeniería de Alimentos para el Desarrollo (IIAD), Departamento de Tecnologia de Alimentos, Universidad Politécnica de Valencia, Valencia, Spain

Contact the author

Keywords

Spectroscopy, grapevine organs, clustering, classification

Tags

IVAS 2022 | IVES Conference Series

Citation

Related articles…

How small amounts of oxygen introduced during bottling and storage can influence the metabolic fingerprint and SO2 content of white wines

The impact of minute amounts of headspace oxygen on the post-bottling development of wine is generally considered to be very important, since oxygen, packaging and storage conditions can either damage or improve wine quality. This is reflected in the generalised use of inert bottling lines, where the headspace between the white wine and the stopper is filled with an inert gas. This experiment aimed to address some open questions about the chemistry of the interaction between wine and oxygen, crucial for decisions regarding optimal closure. While it is known that similar amounts of oxygen affect different wines to a variable extent, our knowledge of chemistry is not sufficient to construct a predictive method.

Effect of Yeast Derivative Products on Aroma compounds retention in model wine

For many years, enological research has developed commercial formulates of yeast derivatives as stabilizing agents and technological adjuvants in winemaking. These products are obtained from yeast by autolytic, plasmolytic, or hydrolytic processes that liberate many macromolecules from the yeast cell, principally polysaccharides and oligosaccharides and most specifically mannoproteins that are well known for their ability to improve tartaric stability and to reduce the occurrence of protein hazes (Ángeles Pozo-Bayón et al., 2009; Charpentier & Feuillat, 1992; Morata et al., 2018; Palomero et al., 2009).

Dry leaf hyperspectral reflectance predicts leaf elemental composition in grafted hybrids

Elemental composition, measured as the concentrations of different elements present in a given tissue at a given time point, is a key indicator of vine health and development. While elemental composition and other high-throughput phenotyping approaches yield tremendous insight into the growth, physiology, and health of vines, costs and labor associated with repeated measures over time can be cost-prohibitive. Recent advances in handheld sensors that measure hyperspectral reflectance patterns of leaf tissue may serve as an affordable proxy for other types of phenotypic data, including elemental composition. Here, we ask if reflectance patterns of dried Chambourcin leaf tissue from an experimental grafting vineyard can predict the known elemental composition of those leaves.

Managing changes in taste: lessons from champagne in britain 1800-1914

This paper focuses on how taste in wine (and other foods) changes and the implications of this process
for producers and merchants.
It draws primarily on the changing taste of and taste for champagne in Britain in the 19th century. Between 1850 and 1880 champagne went from a dosage level of around 20% (20 grams sugar / litre) to 0%. Champagne became the ‘dinner wine of the elite – drunk with roast meat and savoury dishes.
Contemporaries accepted that while most people could distinguish the taste of good champagne from that of bad, very few could distinguish very good from good.

Terpenoid profiles and biosynthetic gene expression pattern in Asti DOCG white muscat grapes at ripening as affected by different canopy management protocols

Aim: The main goal of this study was to find an efficient canopy management to limit the high temperature-related aroma losses of White Muscat grapes, and consequently to preserve the quality standards of Asti DOCG wines.