 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

Exploring the plasticity of the grapevine drought physiology

Grapevine response to water deficit has been extensively studied. Nevertheless, debate still exists regarding some physiology adoption under drought

Quantification of newly identified C8 aroma compounds in musts and wines as an analytical tool for the early detection of Fresh Mushroom Off-Flavor

The Fresh Mushroom Off-Flavor (FMOff) is a concerning undesirable aroma in wine specific of certain vintages, characterized by a typical button mushroom aroma. The appearance of this off-flavor is linked to the presence of certain fungus on the grape [1-3].

The challenge of improving oenological quality in favorable conditions for productivity

Marselan (Cabernet-Sauvignon x Grenache), has been planted for more than 20 years now in Uruguay. Due to its good agronomic and oenological aptitudes under uruguayan conditions, it is currently the red variety with highest plantation rate. The objective of the study was to identify management practices, aimed at improving quality in highly productive vineyards, different fruit/leaf regulation methods were tested in southern Uruguay.

El medio natural de Chile como factor de adaptación de la vid

Chile, junto con Australia, EE.UU., Sudáfrica, Argentina y Nueva Zelanda constituye el grupo de países del nuevo mundo vitivinícola. Todos ellos en conjunto han experimentado en la última década

Phenological characterization of a wide range of Vitis Vinifera varieties

In order to study the impact of climate change on Bordeaux grape varieties and to assess the adaptation capacities of candidates to the grape varieties of this wine region to the new climatic conditions, an experimental block design composed of 52 grape varieties was set up in 2009 at the INRAE Bordeaux Aquitaine center. Among the many parameters studied, the three main phenological stages of the vine (budburst, flowering and veraison) have been closely monitored since 2012. Observations for each year, stage and variety were carried out on four independent replicates. Precocity indices have been calculated from the data obtained over the 2012-2021 period (Barbeau et al. 1998). This work allowed to group the phenological behaviour of the grapevine varieties, not only based on the timing of the subsequent developmental stages, but also on the overall precocity of the cycle and the total length of the cycle between budburst and veraison. Results regarding the variability observed among the different grape varieties for these phenological stages are presented as heat maps.