Enoforum 2021
IVES 9 IVES Conference Series 9 Enoforum Web 9 Enoforum Web Conference 2021 9 Cellar session 9 Non-invasive quantification of phenol content during red wine fermentations

Non-invasive quantification of phenol content during red wine fermentations

Abstract

Phenolic compounds are responsible for the most important red wine quality attributes. Anthocyanins and tannins play crucial roles in color and mouthfeel properties of red wines. Phenolic analysis in the winery is hindered by analytical constrains. The possibility to quantify phenolic content non-invasively from a fermenting tank will provide phenolic data in real time and with absence of sampling. This could be achieved by making use of the fluorescence properties of phenolic compounds. Front-face fluorescence was in this case used to obtain fluorescence spectral properties of wines directly during the fermentation tank. Adapting the sample geometry, direct measurement from a fermenting tank through a crystal window can be obtained. Moreover, the fluorescence spectral properties were correlated with phenolic levels using machine learning techniques and accurate spectral calibrations were obtained for total phenol content, anthocyanins (mg/L) and tannins (mg/L). A prototype device for the measurement of fluorescence spectral properties was developed. The fluorescence spectrometer showed the ability to quantify phenolic content during red wine fermentations with the absence of sampling and in a non-invasive manner.  

DOI:

Publication date: April 23, 2021

Issue: Enoforum 2021

Type: Article

Authors

Jose Luis Aleixandre Tudo1, Isabel dos Santos1, Wessel du Toit1, Gurthwin Bosman2

1 South African Grape and Wine Research Institute (SAGWRI), Department of Viticulture and Oenology, Stellenbosch University, South Africa
2 Department of Physics. Stellenbosch University, Stellenbosch, South Africa

Contact the author

Tags

Enoforum 2021 | IVES Conference Series

Citation

Related articles…

Role of Grape-Extractable Polyphenols in the Generation of Strecker Aldehydes and in the Instability of Polyfunctional Mercaptans during Wine Oxidation

Wine longevity is a complex multifactor phenomenon in which the weight of the different factors is not well known. One of the key factors of wine longevity is related to its resistance to oxidation. This property can be defined as the ability of the wine, under an exposure to oxygen, to keep its color, avoid accumulation of acetaldehyde and Strecker aldehydes (SA), and keep as long as

Ellagitannins and flavano-ellagitannins: concentration ranges in different areas and sensory evaluation

C-Glucosidic ellagitannins, which are the main polyphenolic compounds in oak heartwood, are extracted by wine during aging in oak barrels. Although such maturing of alcoholic beverages in oak barrels is a multi-centennial practice, very little is known on the impact of these ellagitannins on the organoleptic properties of red wine. The objectives of the present investigation were (i) to isolate oak ellagitannins and to hemisynthesize some made-in-wine flavano-ellagitannins, such as acutissimin A; (ii) to analyse their concentration ranges depending on the cultivar area and (iii) to evaluate their sensory impact on the basis of their human threshold concentrations and dose/response relationships in different types of solutions.

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Proposal of zonification and characterization of terroirs in the Yalde-Najerilla-Uruñuela vine growing area (DOC Rioja, Spain), based on the soil influence

Natural Terroir Units (NTU) are being delimited in vine growing area DOCa Rioja, in collaboration with Uruñuela Cooperative, to characterized specific and singular Tempranillo (Vitis vinifera

Survey assessing different practices for mechanical winter pruning in Southern France vineyards

Winter pruning is today the longest operation for hand workers in the vineyard. Over the last years, mechanical pruning practices have become popular in southern France vineyards to respond to competitiveness issue especially for the basic and mid-range wine production. Wine farmers have developed different vineyard management techniques associated with mechanical winter pruning. They sought to be precise or not to control the buds number per vine.