Integrated use of ozonized water for a better management of sulphites in winery
The modern wine consumer is more and more focused on health aspects and rewards genuine products. Therefore reducing the use of harmful chemicals both in vineyard and cellar is one of the the main target of the research. With a totally innovative approach, the project will introduce yeast strains, belonging to the Starmerella bacillaris species into the vineyard. These yeasts has antifungal activity ( aganist the grey mould rot) and, once they reach the cellar on grape surfaces, they start alcoholic fermentation improve the quality of the wine without requiring the sulfite addition.
During grape ripening the vineyards will be treated with increasing concentrations of Starmerella bacillaris. In some cases, before yeast addiution the vineyard will be treated with with ozonized water to improve the colonization performance of Starmerella. The diffusion of the gray mold rot on the grape cluster will be assessed comparing untreated control. The grapes will be harvested and processed. In the vineyard and during the fermentation process, the presence of Starmerella will be quantified by microbiological and molecular analyzes. The wine quality will be assessed.
Sulfur dioxide and sulphites in general are among the most common environmental pollutants and preservatives used in the food industry. The negative effects of sulphites on human health have been extensively documented. In cellar, sulphites are added to the must before starting alcoholic fermentation and at the end of fermentation to block the activity of harmful microorganisms and to protect wine from oxidation. In the first case it is important to add sulfur dioxide as soon as possible, in order to avoid the development of spoilage yeasts present on the grape bunch which can attribute unpleasant organoleptic characters to the wine. Many less toxic molecules have been tested with the aim of replacing sulphites during finification, but to date no equally effective solution has been obtained.
In the industrial winemaking, the pathogenic microorganisms responsible for the deterioration of the fruit must be avoided to reach high grape quality. This is accomplished through the use of pesticides. These molecules are toxic to humans both through inhalation and through the consumption of wine. They are able to alter the soil ecosystem and contaminate water springs. Therefore their use should be reduced, if not avoided. An harmless and sustainable alternative to pesticides is represented by the use of antagonistic microorganisms, the bio-control agents, which are able to compete with pathogens and therefore to defeat them.The yeasts used in the project as bio-control agents have been isolated by the Research Group of the University of Padua from grape bunches collected in vineyards in the Veneto region and therefore are part of the microbial community that characterizes local wine production.
Protocol for recovering microbial cells from the surface of grape bunchs and must and procedure for extracting microbial DNA
The main objective of the project is to evaluate the effectiveness of the yeast Starmerella bacillaris as a biocontrol agent in the vineyard and, when the grapes treated with the microorganism are processed in cellar, as co-starter in winemaking. To exhibit its activity, this yeast must colonize the surface of the grapes and consequently the must. Therefore, identification systems that allow to quantify the microorganism both in vineyard and in cellar must be available. These methods are based on the analysis of DNA form the microrganisms present on the surface of the grape and in the must. These matrices are complex and rich in substances (polyphenols, sugars, organic acids) which inhibit the enzymatic activities used in the identification analyzes. For this reason during the first part of the project existing DNA extraction protocols were adapted to analyze these plant matrices by comparing different methods and commercial KITS . In addition, various washing procedures of the grape bunch were tested in order to develop the procedure that allows to collect the highest number of microbial cells.
Molecular protocol for identification and quantification of Starmerella bacillaris
In order to quantify Starmerella bacillaris in vineyards and in must and to evaluate its impact on the microbial community of the grape bunch and on the presence of the gray mold rot (Botrytis cinerea), a molecular identification protocol has been developed. Since the genomic sequence of the yeast strain was previously determined by the Research Team (University of Padova), a unique DNA region, only present in the tested strain of S. bacillaris, have been identified. These DNA region, if amplified, allows the unanbiguos strain identification. Through the use of quantitative PCR, the number of copies of the specific sequence present in the sample can be determined, allowing to calculate yeast concentration.
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Sito web del progetto
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Article - Enolo - Ozoned water in the vineyard in the name of sustainability!
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Article - ValdoTV - The results of the Ozoplus Grape and Ozoplus Wine Projects were presented
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Consorzio delle Venezie DOC
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