 IVES 9 IVES Conference Series 9 Phenolic extraction and mechanical properties of skins and seeds during maceration of four main italian red wine grape varieties

Phenolic extraction and mechanical properties of skins and seeds during maceration of four main italian red wine grape varieties

Abstract

AIM: Red grape varieties are characterized by different phenolic contents (prominently tannins and anthocyanins) found in skins and seeds. The extractability of these compounds varies during maceration, as well as the mechanical properties of skins and seeds. Four main Italian red winegrape varieties were tested to understand these differences during a simulated maceration process.

METHODS: Vitis vinifera L. cv. Aglianico, Nebbiolo, Primitivo, and Sangiovese grape skins, seeds, and joint skin+seeds were subjected to 10-day simulated maceration in a buffer solution (pH 3.40), with increasing contents of ethanol to simulate the fermentation trend. The phenolic extractable content (tannins and anthocyanins by spectrophotometry and HPLC) was evaluated during the simulated maceration. Mechanical-acoustic properties of skins and seeds were performed before and after maceration.

RESULTS: The combined total phenolics release during the maceration of separately-extracted seeds and skins were higher compared to the joint extraction (seeds+skins); in this latter case, the seeds contribution become significant (p < 0.05) after 3 (Nebbiolo), 4 (Aglianico) or 10 days (Primitivo and Sangiovese). In three cases out of four the anthocyanin content was found slightly reduced when the seeds were jointly present: these appeared red-coloured at the end of the maceration, and a further extraction and quantitation of the colouring matter retained by seeds was conducted. Diverging effects on the skin or seeds mechanical-acoustic measurements were found with the maceration process, depending by the variety.

CONCLUSIONS

Varietal differences were highlighted in phenolic compounds simulated extraction from solid parts, particularly for seeds contribution and for their ability to hold colour pigments.

ACKNOWLEDGMENTS

MIUR project PRIN n. 20157RN44Y. P. Arapitsas, A. Gambuti, M. Marangon, L. Moio, L. Nouvelet, G. Parpinello, D. Perenzoni, L. Picariello, D. Slaghenaufi, G.B. Tornielli, A. Versari, S. Vincenzi

DOI:

Publication date: September 7, 2021

Issue: Macrowine 2021

Type: Article

Authors

Simone Giacosa

University of Torino, Italy – Maria Alessandra PAISSONI, University of Torino, Italy – Susana RÍO SEGADE, University of Torino, Italy – Andrea CURIONI, University of Padova, Italy – Fulvio MATTIVI, University of Trento, Italy – Paola PIOMBINO, University of Napoli, Italy – Arianna RICCI, University of Bologna, Italy – Maurizio UGLIANO, University of Verona, Italy – Vincenzo GERBI, University of Torino, Italy – Luca ROLLE, University of Torino, Italy

Contact the author

Keywords

italian red winegrapes, phenolic extraction, anthocyanins, tannins, grape seeds

Citation

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.

Wine industry, digital transformation, and sustainability: a systematic literature

This paper aims to (i) identify the state of the art regarding digital transformation in the transition to sustainability in the wine industry, (ii) analyze the adoption of digital technologies at different stages of the winemaking process and their contribution to the triple bottom line of sustainability, and (iii) present a research agenda that facilitates the development of the field, providing contributions to both literature and managerial practice.

Usefulness and limits of the crop water stress index obtained from leaf temperature for vine water status monitoring

Aims: This work aimed i) to calibrate the accuracy of estimating vineyard water status by crop water stress index (CWSI) compared to stem water potential; ii) to determine the time interval during the day that best correlates to stem water potential and iii) to understand the its usefulness.

Physico-chemical properties of vine pruning residues with potential as enological additive

Grapes are one of the world’s primary fruit crops, and pruning activities generate high amounts of annual wood wastes [1]. These pruning shoots contain valuable phenolic compounds and could have numerous potential applications [1,2]. Consequently, the aim of this work was to evaluate the physico-chemical properties of vine pruning residues with potential as enological additives. For this purpose, grapevine shoots from 12 varieties grown in Chile were collected during the winter of 2021.

Classification of “Valpolicella Superiore” wines in relation to aromatic composition: influence of geographical origin, vintage and aging

The Valpolicella appellation, mainly known for Amarone and Ripasso, is experiencing growing interest in Valpolicella Superiore (VS), a lighter red wine aligning with consumer demand. However, anecdotal evidence suggests different stylistic interpretations of VS, potentially causing consumer confusion.