Macrowine 2021
IVES 9 IVES Conference Series 9 The influence of initial phenolic content on the outcome of pinot noir wine microoxygenation

The influence of initial phenolic content on the outcome of pinot noir wine microoxygenation

Abstract

Over the years, microoxygenation (MOX) has become a popular vinification technique to improve wine sensory qualities. However, among the impacting factors reported, only one published study (Cano-López et al. 2008) investigated the effects of initial phenolic content on wines undergoing MOX. The present study aims to establish the importance of this factor and specifically on light-coloured Pinot noir wines.Two Pinot noir wines with a low (PN1) and high (PN2) phenolic content were sterile filtered after malolactic fermentation and treated with two oxygen doses (i.e., 0.50 ± 0.08 and 2.17 ± 0.3 ppm/day) for 14 days with temperature control at 15oC. Control treatments had no MOX. Afterwards, the wines were aged for 1 month and followed by addition (100 mg/L) with the end point determined 4 days later.The results highlighted the importance of having high anthocyanin content for Pinot noir wines subjected to MOX on colour development. A higher anthocyanin content significantly increased colour intensity and resistant pigments in association with a greater increase in polymeric pigments. However, it did not guarantee colour stability, and bleaching erased the improvement on colour intensity in all wines.

We speculated that improvement of colour stability by MOX would be dependent on acetaldehyde production, forming pigments with the ethyl-bridged covalent bond that is more resistant to cleavage and bleaching. In this trials, limited acetaldehyde formation would expect after the removal of yeast with sterile filtration. Regarding tannin composition, MOX accelerated the decrease of (-)-epigallocatechin extension units in both PN1 and PN2. In PN1, the higher oxygen dosage led to the higher formation of tannin macromolecules and significantly lower tannin yield and (+)-catechin extension units, increasing the proportion of tannin terminals units.

These could be of concern for astringency perception (Ma et al. 2014). Therefore, MOX should be applied to Pinot noir and other low phenolic wines with caution.

DOI:

Publication date: September 13, 2021

Issue: Macrowine 2021

Type: Article

Authors

Yi Yang (Billy) 

The University of Auckland, New Zealand,Paul A. Kilmartin, The University of Auckland Rebecca C. Deed, The University of Auckland Leandro D. ARAUJO, Lincoln University

Contact the author

Keywords

microoxygenation, initial phenolic content, colour development, tannin composition, pinot noir wine

Citation

Related articles…

Comparison of imputation methods in long and varied phenological series. Application to the Conegliano dataset, including observations from 1964 over 400 grape varieties

A large varietal collection including over 1700 varieties was maintained in Conegliano, ITA, since the 1950s. Phenological data on a subset of 400 grape varieties including wine grapes, table grapes, and raisins were acquired at bud break, flowering, veraison, and ripening since 1964. Despite the efforts in maintaining and acquiring data over such an extensive collection, the data set has varying degrees of missing cases depending on the variety and the year. This is ubiquitous in phenology datasets with significant size and length. In this work, we evaluated four state-of-the-art methods to estimate missing values in this phenological series: k-Nearest Neighbour (kNN), Multivariate Imputation by Chained Equations (mice), MissForest, and Bidirectional Recurrent Imputation for Time Series (BRITS). For each phenological stage, we evaluated the performance of the methods in two ways. 1) On the full dataset, we randomly hold-out 10% of the true values for use as a test set and repeated the process 1000 times (Monte Carlo cross-validation). 2) On a reduced and almost complete subset of varieties, we varied the percentage of missing values from 10% to 70% by random deletion. In all cases, we evaluated the performance on the original values using normalized root mean squared error. For the full dataset we also obtained performance statistics by variety and by year. MissForest provided average errors of 17% (3 days) at budbreak, 14% (4 days) at flowering, 14.5% (7 days) at veraison, and 17% (3 days) at maturity. We completed the imputations of the Conegliano dataset, one of the world’s most extensive and varied phenological time series and a steppingstone for future climate change studies in grapes. The dataset is now ready for further analysis, and a rigorous evaluation of imputation errors is included.

Analisi delle modalita’ d’interazione tra conoscenza dl un territorio e gestione dei suoi aspetti enoturistici relativamente ad una regione (Toscana)

Il Turismo negli anni 2000 si appresta ad essere la più vasta ed estesa impresa presente nel mondo. Se a cio si aggiunge il fatto che il tempo libero risulta essere, per la maggior parte delle persone, la principale aspirazione da considerare ben oltre il proprio benessere eco­nomico, ci si rende conto del perché di una crescente domanda di ecoturismo. Un viaggiare sempre più accorto aile valenze ambientali e tipiche di un territorio.

Hierarchy of the interactions between physical and biological parameters intervening in the Pyrenean Gascon foothill vineyard

Un travail sur les A.O.C. du piémont pyrénéen occidental permet de construire une hiérarchie de paramètres climatiques, géo-pédologiques, morphologiques, de saisir leurs niveaux d’interaction et d’élaborer une méthodologie pour proposer un zonage

Grapevine nitrogen retrieval by hyperspectral sensing at the leaf and canopy level

Grapevine nitrogen (N) monitoring is essential for efficient N management plans that optimize fruit yield and quality while reducing fertilizer costs and the risk of environmental contamination. Unlike traditional vegetative-tissue sampling methods, remote sensing technologies, including hyperspectral imaging, have the potential to allow monitoring of the N status of entire vineyards at a per-vine resolution. However, differential N partitioning, variable spectral properties, and complex canopy structures hinder the development of a robust N retrieval algorithm. The present study aimed to establish a solid understanding of vine spectroscopic response at leaf and canopy levels by evaluating the different nitrogen retrieval approaches, including the radiative transfer model.

Characterization of simple polyphenols in seeds of autochthonous grapevine varieties grown in Croatia (Vitis vinifera L.)

Croatia has rich grapevine genetic resources with more than 125 autochthonous varieties preserved. Coastal region of Croatia, Dalmatia, is well known for wine production based on autochthonous grapevine varieties. Nevertheless, only couple of these are widely cultivated and have greater economic importance. Grape seeds are sources of polyphenols which play an important role in organoleptic and nutritional value of grape and wine. Hence, the aim of this study was to evaluate the simple polyphenols from grape seeds in 20 rare autochthonous grapevine varieties.