 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

Towards understanding the mechanisms of resistance to grapevine Flavescence dorée

Flavescence dorée (FD) is a very serious grapevine disease, classified as quarantine in europe, where it appeared in the middle of the last century. It is associated with the presence of phytoplasmas, transmitted in the vineyard by a leafhopper of american origin, scaphoideus titanus. FD causes severe wine production losses and often leads to plant death. There are currently no alternative solutions to insecticide treatments against the vector and uprooting diseased vines.

TCA – A status report on South African cork closures

Cork taint decreases the commercial value of wine as tainted wines are rejected by consumers. Although other compounds in wine and cork can also be responsible for causing a taint, 2,4,6-trichloroanisole (TCA) is regarded as the primary cause of cork taint. As cork taint is often used in marketing campaigns against natural cork closures,

Highlighting a link between the structure of mannoproteins and their foaming properties in sparkling wines

Effervescence and foaming properties are the main visual characteristics assessed by the consumer during
sparkling wine tasting.

Résistance stomatique et caractérisation hydrique des terroirs viticoles

The analysis of the distribution of natural plant populations allows an ecological characterization of cultivated environments in thermal, water and trophic terms; it guides the choice or selection of plants (or grape varieties) to cultivate (Astruc et al ., 1984, 1987; Delpoux, 1971; Jacquinet and Astruc, 1979). This approach has given good results in areas where the topography is the determining factor in the ecological differentiation of the terroirs.

Sorption of aroma compounds by commercial specific yeast derivatives and the influence of polyphenols

Specific inactivated yeast derivatives (SYDs) from S. cerevisiae are obtained through thermal, mechanical, and enzymatic processes and are used to enhance wine quality.