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…

Assay of distinct modes of polysaccharidases dosage in vinification with cv. Malbec. Effects on microbiological evolution, color and skin depletion

In the maceration stage of winemaking, enzymes can be used to degrade the polysaccharides present in the cell walls and middle sheets, and thus facilitate the extraction of juice and the release of polyphenols and aroma precursors retained in the grape skins.

Effect of one-year cover crop and arbuscular mycorrhiza inocululation in the microbial soil community of a vineyard

The microbial composition of the soil is an important factor to consider in viticulture, since its influence on the “terroir” and on the organoleptic properties of the wine have been demonstrated. Different agronomic techniques have the potential to modify the composition and functionality of the soil microbial community. Maintaining green covers is known to increase soil microbial diversity. The direct application of inoculum of beneficial microorganisms to the soil has also been used to increase their abundance. However, the environmental conditions of each site seem to have a determining weight in the result of these practices. In this study, we compared the effect on the microbial community of a cover crop with legumes in autumn and the inoculation of grapevines with commercial inoculum bases on Rhizophagus irregularis and Funeliformis mosseae in the previous spring. The study has been carried out in a vineyard in Binissalem, Mallorca, Spain. After applying the treatments, we will analyze the soil microbial communities using the data obtained from Illumina amplification of soil DNA from the 16S and ITS regions to analyze bacteria and fungi community, respectively. In addition, we will record the physicochemical characteristics of the soil at each sampling point. The result showed that agronomic management, in the short term, has less influence than soil characteristics on the composition of the soil microbiome. With these results, we can conclude that in a vineyard, agricultural techniques should focus on improving the characteristics of the soil to improve the biodiversity of the soil microbiota.

Residual copper quantification on grapevine’s organs

Copper is listed among the active substances candidates for substitution (Regulation EU 2015/408). Yet still, because of the lack of valid alternatives, the European Commission recently confirmed its usage authorization by limiting the maximum amount to 28 Kg per hectare in 7 years, i.e. an average of 4 kg/year (Reg. EU 2018/1981).This restriction is due to copper accumulation in soils and surface waters both caused by a steady application, especially on perennial crops (Riepert et al., 2013). The aim of this work is to determine if treatments with reduced copper dosages are able to reach different grapevine’s organs, with particular focus on the core of bunches, and if these small amounts can ensure the respect of the legislative prescription, without compromising the phytosanitary conditions of the vineyards, thus grape yields.

Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines – The case study of malolactic fermentation

In this study, stationary and time-resolved fluorescence signatures were statistically and chemometrically analyzed among three typologies of Chardonnay wines with the objectives to evaluate their sensitivity to acidic and polyphenolic changes.

Enological and nutraceutical potential of some grape varieties tolerant to downy mildew and powdery mildew

AIM: Since 2012 the Veneto Region regulation (north-east Italy) allowed wine production using 20 hybrid grapevine varieties selected for their high tolerance to downy mildew and powdery mildew. Characterized by vigour, high grape productivity and low pesticide use, these varieties are suitable to develop sustainable viticulture in mountain areas located at medium altitudes.