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…

Does spotted lanternfly phloem-feeding have downstream effects on wine volatiles? Preliminary insights into compositional shifts

The Spotted lanternfly (SLF), first detected in the U.S. in 2014, is an invasive phloem-feeding planthopper that poses a growing threat to grape and wine production in the U.S. In Pennsylvania, where it was first detected, reductions in grapevine production and fruit quality have been reported by commercial growers. Recent advances have begun to elucidate how SLF affects grapevine physiology and resource allocation, but no research has identified how SLF affects wine chemical composition and quality. Documented reductions in fruit sugar allocation due to heavy SLF phloem-feeding may have downstream effects on wine fermentation dynamics. Additionally, secondary metabolic responses stimulated by SLF may also influence berry chemical composition. The present study investigated SLF-mediated effects on wine composition through analysis of the volatile composition of wines produced from white- and red-fruited varieties of different Vitis parentage (e.g., Vitis vinifera vs. interspecific hybrids) following prolonged exposure to adult SLF phloem-feeding.

Vineyard floor management intensity impacts soil health indicators and biodiversity across South Australian viticultural landscapes

Vineyard floors in warm, dry landscapes including those in South Australia, have traditionally been managed using intensive practices such as tillage and herbicides to control weeds and vegetation, thereby limiting competition with grapevines for water and nutrients in order to not compromise yields.

Interaction Between Armenian Clay-based Ceramic and Model Wine

Clay-based ceramic vessels (jars, pyhtoi, etc.) for wine fermentation and aging processes have been used in several cultures for millennia. This know-how still in practice in several countries of the Armenian highland is gaining worldwide in curiosity, popularity, and interest. Ceramic pots are famous among traditional winemakers for their benefits such as temperature regulation, natural cooling system, favorable oxygen exchange, and impact on pH, which are different from those of stainless steel, wood barrels, or concrete.

Evaluation of terroir suitability for vine cultivation in new areas using geographic multi-criteria decision support

Based on historical vine cultivation, the recent development of wine production in Drama wine region (Greece) has led to vine cultivation expansion of white and red varieties. The current cultivation of 500 ha of vineyards is expected to increase in the coming years. Natural terroir units (NTU) have been designed recently to support the production of high quality wines in the region [1]. The aim of this work is to evaluate the relevancy of the proposed NTUs regarding their suitability to produce wines of specific sensorial identity, and to provide guidelines for correct site selection for the expanding wine industry of the region.

Rapid damage assessment and grapevine recovery after fire

There is increasing scientific consensus that climate changeis the underlying cause of the prolonged dry and hot conditions that have increased the risk of extreme fire weather in many countries around the world. In December 2019, a bushfire event occurred in the Adelaide Hills, South Australia where 25,000 hectares were burnt and in vineyards and surrounding areas various degrees of scorching and infrastructure damage occurred. The ability to coordinate and plan recovery after a fire event relies on robust and timely data. The current practice for measuring the scale and distribution of fire damage is to walk or drive the vineyard and score individual vines based on visual observation. The process is time consuming, subjective, or semi-quantitative at best. After the December 2019 fires, it took many months to access properties and estimate the area of vineyard damaged. This study compares the rapid assessment and mapping of fire damage using high-resolution satellite imagery with more traditional ground based measures. Satellite imagery tracking vineyard recovery in the season following the bushfire is being correlated to field assessments of vineyard productivity such as canopy health and development, fertility and carbohydrate storage. Canopy health in the seasons following the fires correlated to the severity of the initial fire damage. Severely damaged vines had reduced canopy growth, were infertile or had very low fertility as well as lower carbohydrate levels in buds and canes during dormancy, which reduced productivity in the seasons following the bushfire event. In contrast, vines that received minor damage were able to recover within 1-2 years. Tools that rapidly and affordably capture the extent and severity of damage over large vineyard area will allow producers, government and industry bodies to manage decisions in relation to fire recovery planning, coordination and delivery, improving the efficiency and effectiveness of their response.