 IVES 9 IVES Conference Series 9 Influence of must fining on oxygen consumption rate, oxidation susceptibility and electrochemical characteristics of different white grape musts

Influence of must fining on oxygen consumption rate, oxidation susceptibility and electrochemical characteristics of different white grape musts

Abstract

AIM: Pre-fermentative fining is one of the central steps of white wine production. Mainly aiming at reducing the levels of suspended solids, juice fining can also assist in reducing the content of oxidizable phenolics and therefore the susceptibility of juice to oxidation. There is a large variety of fining agents available on the market, many of which have been introduced in recent years in response to specific dietary requirements. The aim of this work is to characterize different fining agents for their ability to reduce oxidation susceptibility of must of different white grape varieties.

METHODS: Musts of Pinot grigio, Garganega and Chardonnay were produced in the laboratory and submitted to different fining treatments by means of casein, PVPP, potato protein, pea protein, or combinations of potato protein and PVPP. All fining also included pectolitic enzymes. Following cold settling, clear juice was racked and submitted to chemical and electrochemical (linear sweep voltammetry, LSV) analyses, as well as to cycles of controlled oxygen consumption to assess oxidative behaviors. A control treatment consisting of cold settling only with pectolitic enzymes was used as control.

RESULTS: Not all fining treatments were able to impact juice oxidative behavior. Common fining agents such as casein showed marginal impact on oxygen consumption rates, content of oxidizable phenolics and browning susceptibility. Conversely, pea protein, alone or in combination with PVPP, showed great capacity to reduce the content of oxidizable phenolics and the ability of the must to undergo oxidative reactions. LSV could be used to effectively monitor the removal of oxidizable phenolics during the treatment.

CONCLUSIONS:

This work illustrates the importance of the type of fining agent in the context of managing must and wine oxidation susceptibility. It also highlights the potential of a simple electrochemical technique such as LSV to monitor the effectiveness of fining towards oxidizable phenolics. ACKNOWLEDGMENTS: The present work was financially supported by Biolaffort

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Maurizio Ugliano

University of Verona, Italy,Virginie, MOINE, Biolaffort, France Arnaud, MASSOT, Biolaffort, France

Contact the author

Keywords

fining, vegetable proteins, oxidation, lienar sweep voltammetry

Citation

Terroir factors causing sensory and chemical variation in Riesling wines

The term “terroir”, originated in France, comprises the interaction of soil, climate, and topography with the vines of a specific variety and may be extended to the human impact due to the active choice of viticultural and oenological treatments.

The influence of different fertiliser applications and canopy management practices on the potassium content and pH of juice and wine of Vitis vinifera L. cvs. Cabernet-Sauvignon and Cabernet franc

In an attempt to reduce the pH of juice and wine, different fertiliser applications and canopy management practices were evaluated in South Africa in a field trial. Fertiliser treatments entailed no, CaSO4, Ca(OH)2, and MgSO4 fertilisation.

Induction of polyphenols in seedlings of Vitis vinifera cv. Monastrell by the application of elicitors

Contamination problems arising from the use of pesticides in viticulture have raised concerns. One of the alternatives to reduce contamination is the use of elicitors, molecules capable of stimulating the natural defences of plants, promoting the production of phenolic compounds (PC) that offer protection against biotic and abiotic stress. Previous studies on Cabernet-Sauvignon seedlings demonstrated that foliar application of elicitors methyl jasmonate (MeJ) and benzothiadiazole (BTH) increased proteins and PC involved in grapevine defence mechanisms. However, no trials had been conducted on Monastrell seedlings, a major winegrape variety in Spain.

Diagnosis of soil quality and evaluation of the impact of viticultural practices on soil biodiversity in a vineyard in southwestern France

Viticulture is facing two major changes – climate change and agroecological transition. In both cases, soil quality is seen as a lever to move towards a more sustainable viticulture. However, soil biological quality is little considered in the implementation of viticultural practices. Gascogn’Innov (2017-2022) is an Operational Group funded by the European Innovation Partnership for Agriculture. As such, it brings together winegrowers from the south-west of France, scientists, advisors and technicians, around a project focused on viticultural soil biological functioning and the design of technical routes more respectful toward soil heritage. To achieve this, the project aims to acquire references on the impact of viticultural practices on soil biology from a dynamic way, and to test a methodology to integrate information provided by the soil bioindicators to manage farming systems. A set of indicators of soil biological quality are evaluated in the project: microorganisms (bacteria and fungi abundance and diversity), fauna (abundance and diversity of nematodes and earthworms), physico-chemical characteristics, soil structure assessment and degradation rate of organic matter. Based on a network of 13 plots that have been subject to an initial diagnosis in 2017, several agronomical practices to restore soil fertility are experimented to redesign the cropping system (for instance plant cover, organic matter inputs, reduction of herbicides, mineral fertilizers). System redesign was made in collaboration by winegrowers and an interdisciplinary group of experts (agronomists, biologists). Several indicators are measured on vine and soil at each vintage to assess vine health and productivity. At the end of the project (2021), a final diagnosis was carried out. Gascogn’Innov allowed to create a regional database on the quality of wine-growing soils, which permitted to evaluate the effect of practices according to soil types. Especially, decreasing the intensity of tillage and increasing the duration and diversity of grass coverage tends to increase the abundance of all the organisms studied. This project confirmed the value of soil biological quality indicators to drive the sustainability of practices, but also highlighted the key-role of expertise, in both agronomy and soil biology, to help winegrowers understand and appropriate their soil quality diagnoses.

Screening of soil yeasts with fermentative capacity from the antarctic continent for their application in the wine industry

AIM: In the last years, many wineries are increasing experimentation to produce more distinguishable beverages. In this sense, the reduction of the fermentation temperature could be a useful tool because it preserves volatile compounds and prevents wines from browning, particularly in the case of white wines.