Macrowine 2021
IVES 9 IVES Conference Series 9 Grape seed flavanols extraction and mechanical-acoustic properties as influenced by maceration time and ethanol content

Grape seed flavanols extraction and mechanical-acoustic properties as influenced by maceration time and ethanol content

Abstract

AIM: Grape flavanols are involved in wine quality markers such as in-mouth sensations and colour stability. In particular, seed flavanols are characterized by low molecular weight and high galloylation ratio, which are correlated respectively with bitterness and astringency. Their release during maceration is derived from the seed hydration and the ethanol-driven disassembly of cell walls that is promoted by maceration time. In this study, acoustic and mechanical parameters were tested to investigate the effect of maceration length and ethanol content on seed flavanols extraction. The magnitude of the changes observed in seeds hardness in the different maceration conditions was evaluated in the attempt to establish correlations with the extracted compounds.

METHODS: Pinot noir seeds were macerated in a wine-like solution (pH 3.40, 5 g/L tartaric acid) with different ethanol content (0, 5, 10, 15 and increasing addition up to 15% v/v). After 3, 7, and 10 days, total polyphenols (A280), condensed tannins (methylcellulose assay), flavanol composition as mean degree of polymerization (mDP), and monomeric content by HPLC were determined in the resulting solutions. Mechanical and acoustic parameters of macerated seeds were evaluated through compression test by instrumental texture analysis.

RESULTS: Seed tannins extraction was influenced by both ethanol and maceration time, in different extent depending on the specific compound. In all macerations, an initial seed deformation together with a loss of elasticity was reported. As well, seed hardness (as seed break force, N) increased in all macerations except for 15% ethanol samples that showed a significant decrease. In accordance, some acoustic parameters (as average acoustic energy, dB) increased significantly during maceration, and this last parameter was positively correlated with total polyphenols and condensed tannins extractions.

CONCLUSIONS:

Initial ethanol content and maceration length influenced flavanols richness and composition in the maceration extract. However, limited differences in both phenolic composition and texture parameters were found between the samples with no ethanol content and gradually-increasing alcohol strength

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Maria Alessandra Paissoni

University of Torino, Italy,Susana RÍO SEGADE, University of Torino, Italy Luca ROLLE, University of Torino, Italy Simone GIACOSA, University of Torino, Italy

Contact the author

Keywords

grape seeds, tannins, maceration, texture analysis, mechanical-acoustic properties

Citation

Related articles…

REGAVID a decision tool to deficit irrigation in a temperate climate (DO Monterrei – Spain)

In temperate climates, such as in the North of Spain, the use of irrigation in the vineyard has not been required, due to the usual rainfall from June to August. In some large vineyards, irrigation management has been carried out, based on occasional support irrigation, or for the application of nutrients (fertigation). Currently it is necessary to implement decision support models to manage irrigation water in real time and avoid misuse of a scarce resource. Moreover, quality standards must be achieved, as in the previous rainfed viticulture.

Evaluation des aptitudes œnologiques des raisins rouges avec l’étude de certains nouveaux indices de maturité phénolique

Pour obtenir des vins d’une certaine gamme, il faut connaître les paramètres liés à la composition de la baie et introduire non seulement les paramètres classiques, c’est-à-dire sucres et acidité, mais aussi les paramètres qui tiennent compte

Experimental vinification of withered grapes of Vitis vinifera “Muscat of Alexandria”

The objective of the present work is to investigate wine produced from dehydrated grapes and vinified according to classical Roman manuals.

METHODS – Locally produced Muscat of Alexandria’s grapes were used for the sweet wine production, grown in the experimental vineyard of Instituto Superior de Agronomia (Lisbon, Portugal). The grapes were harvested manually slightly over-ripe and subjected to greenhouse drying. After 7-10 days dried grapes were transported to an experimental winery for various operations (e.g., grape weighing, sorting, crushing/destemming). Several maceration protocols were used comprising the addition of saltwater and white wine to whole bunches or destemmed grapes. Fermentation was conducted with the addition of commercial yeast. The standard physico-chemical parameters of wines were determined according to the OIV standards.

First results on the chemical composition of red wines from the pressing of marc

In the Bordeaux vineyards, press wine represents approximately 15% of the total volume of wine produced[1]. Valuing this large volume of wine is necessary from an economic point of view, but also because of their organoleptic contribution to the blend, and their contribution to the construction of wines for laying down. Therefore, this study was developed considering the lack of recent scientific knowledge on the composition of red press wines. The aim of this study is to establish an initial assessment of their chemical composition including aromatic compounds and a phenolic part.

Rootstock x environment interaction shapes shoot system phenotypic variation in grafted ‘Chambourcin’

Recent advances in phenomics and transcriptomics have the enhanced capacity for understanding how clonally propagated perennial crops like grapevines respond to their environments seasonally and over the course of multiple years. Because most grapevines are grafted, above-ground grapevine traits reflect scion genotype and its interaction with the local environment. In addition, traits expressed by the scion reflect rootstock genotype and how that rootstock is interacting with its environment seasonally and across years. To investigate rootstock x environment interaction on shoot systems in grafted grapevines we characterized comprehensive phenotypic variation in an experimental vineyard in Mount Vernon, Missouri, USA where the grapevine cultivar ‘Chambourcin’ is growing on its own roots and is grafted to three different rootstocks (‘1103P’, ‘3309C’, ‘SO4’).