 IVES 9 IVES Conference Series 9 The use of fluorescence spectroscopy to develop a variability index and measure grape heterogeneity

The use of fluorescence spectroscopy to develop a variability index and measure grape heterogeneity

Abstract

AIM This work aims to investigate fluorescence spectroscopy as a tool to assess grape homogenates to discriminate between samples of varying maturities and to develop an index to objectively characterise the level of grape heterogeneity present in any given vineyard.

METHODS Cabernet-Sauvignon grape bunches were sampled every ten days from veraison through to harvest from the Coonawarra Geographical Indication of South Australia in 2020. After sorting into maturity classes using density baths,1 berries were homogenised and an Aqualog spectrophotometer was used to record the excitation emission matrix (EEM)2 of each maturity class at each sample date. The pre-processed EEM data underwent parallel factor analysis (PARAFAC) to identify the relevant fluorescence regions that discriminated samples based on maturity. The grape homogenate EEM dataset was then used to formulate a variability index.

RESULTS Chlorophyll and anthocyanin fluorescence signals were identified from EEM data at excitation wavelengths in the range 250 – 700 nm and emission wavelengths between 400 – 800 nm in grape homogenate samples using PARAFAC. Discrimination between samples depending on maturity was achieved using PARAFAC. The variability index was calculated and levels of grape heterogeneity were quantified.

CONCLUSIONS

This work demonstrated the possibility of using grape homogenate EEM data, particularly in the region of chlorophyll and anthocyanin fluorescence, to objectively measure grape heterogeneity by developing a variability index. Grape heterogeneity has been shown to impact Cabernet-Sauvignon wine chemical profile and sensory characteristics.3 Therefore, a tool to analyse grape heterogeneity within a winery could aid viticultural and winemaking decisions to achieve wines of targeted quality and style.

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Claire Armstrong

Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide. ,Adam GILMORE, HORIBA Instruments Inc., Piscataway, United States. Paul BOSS, CSIRO Agriculture and Food and Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide. Vinay PAGAY, Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide. David JEFFERY, Australian Research Council Training Centre for Innovative Wine Production, The University of Adelaide.

Contact the author

Keywords

chemometrics, colour, grape maturity, parafac, vineyard variability

Citation

How the physical components of the terroir can differently intervene in French wines DPO definitions.Example of Côte de Nuits in Burgundy

European regulations describe what elements must be given in the specifications of DPO determination ; mainly production conditions, links between quality and products characteristics and the physical traits of the production area. These elements are given in the “link to terroir” paragraph relating natural and human factors, detailed product characteristics linked to the geographical area and at last interactions between product originality and the geographical area.

Health space in vine spa in the world

This elaboration presents vine spa has precious contribution of social development health and well being in culture of wine regions. The majority of the vine-spas in the world draw raw materials from the vineyard; both for cosmetics treatments and for dishes in their restaurants. Vitis vinifera vine provides fresh grapes for dishes and massages, seeds and oil from the seeds, as well as the leaves, and its extracts, and above all the wine.

Does treatment of grape juice with aspergillopepsin-i influence wine aroma?

Acid aspergillopepsins-i (ap-i) have been suggested for use in winemaking due to their ability to degrade proteins, which reduces haze formation and the necessity for bentonite to achieve protein stability. These endopeptidases cleave non-terminal amino acid bonds of proteins, resulting in their degradation.

DNA-Free genome editing confers disease resistance in grapevine

Grapevine (Vitis Vinifera L.), one of the most important cultivated fruit crops, is facing significant challenges due to climate change. Specifically, increasing temperatures negatively impact the physiological traits and disrupt plant phenology. Additionally, increased virulence in pathogen attacks and pests leads to significant yield loss, requiring widespread application of plant protection products. Traditional agronomic practices offer only partial mitigation, requiring the development of precise and effective intervention strategies. The economic worth of viticulture has prompted continuous efforts in grapevine genetic improvement programs, traditionally involving conventional breeding and clonal selection that, however, are complex and time-consuming approaches.

Soil variability effects on vine rootzones and available water

Aim: The aim of this work is educating people about soil variability, vine rootzone depth and readily available water holding capacity. The concept of terroir is readily discussed in the wine industry but many people involved are unable to describe a soil profile and interpret its limitations that impact on vine growth, fruit quality and wine produced. This paper discusses soil physical characteristics important to vine root growth and readily available water holding capacity (RAW).