 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

Modelisation of the microclimatical parameters for the viticultural ”terroirs”characterization of “Canton de Vaud” (Switzerland)

Dans le cadre d’une recherche sur les terroirs viticoles du canton de Vaud – Suisse, un modèle du microclimat intégrant température, relief, éclairement et pluviométrie a été conçu.

Comparing the effects of vision, smell and taste in red wine quality judgments by experts: sensory cues, mental imagery and verbal representations as drivers of consensus in the multisensory space

In this study, we evaluated the contributions of vision, smell and taste to red wine quality judgments by expert wine tasters.

Sensory impacts of the obturator used for the Chasselas: study over the time

Many parameters affect the organoleptic characteristics of wine: internal parameters like the chemical composition or polyphenol content and external as for example storage conditions or the type of obturator. The aim of this study was to characterize sensorally the impacts of several type of obturator on a white wine: Chasselas. To determine the organoleptic characteristics of this wine, a quantitative descriptive analysis could be used. But rapid sensory methods were preferred in this project. Indeed these methods are an appropriate alternative to conventional descriptive methods for quickly assessing sensory product discrimination.

“Terroir” studies in the Côtes du Rhône controlled appellation: from zoning to application

This work gives a summary of the most important programmes about viticultural « terroirs », developed on the « Côtes du Rhône » controlled appellation area for about twenty years.

Olfactometric and sensory study of red wines subjected to ultrasound or microwaves during their elaboration

The effect that some extraction techniques, such as ultrasound (Cacciola, Batllò, Ferraretto, Vincenzi, & Celotti, 2013; Povey & McClements, 1988) or microwaves (Carew, Close, & Dambergs, 2015; Carew, Gill, Close, & Dambergs, 2014) produce on the aroma of red wines, when applied to processes of extractive nature, such as pre-fermentative maceration or ageing with oak chips (Spanish oak – Quercus pyrenaica and French oak – Quercus robur) has been studied. The volatile profile was determined by means of gas chromatography coupled with olfactometric and mass spectrometric detection. A sensory analysis was also carried out. No indications were found to show that the pre-fermentative treatment with microwaves or ultrasound modified the sensory profile of the wines whereas the application of such energies during the ageing phase showed some positive trends at sensory level.