Wine quality and shelf-life. Implementing wine quality evaluation procedures and process monitoring procedures
The aim of the project is twofold: 1) providing wineries with innovative tools for rapid measurements of the chemical composition of red grapes, consisting in the calculation of indexes of the content in secondary metabolites (polyphenols and aromas) to be used for the assessment of the global quality and of the commercial value of the grapes; 2) introducing in wineries new rapid systems for monitoring ageing wines to improve the efficiency of the controls (reduction of risk of alterations), in order to support companies that implement strategies aimed at optimizing the production process (precision oenology) and at reducing the use of additives (sustainability).
The project is divided into 4 activities: the first (A1) concerns the development of rapid methods to evaluate the composition of red grapes by comparing these methods with conventional laboratory methods; the survey concerns grapes coming from different wineries that are representative of the variability of the territory. These methods will be used in the wineries (A2) for the characterization of the grapes and a computerized system will support the data collection. A similar procedure will be adopted for the development (A3) and the introduction in the wineries (A4) of rapid methods for the control of malolactic fermentation and the monitoring of ageing wines.
"In Piedmont, 45,000 hectares are planted with vineyards, mainly distributed in the hills and in the alpine and pre-alpine areas. Regarding the company size, 58% of the total area is represented by medium-small companies with extension < 1 ha.
It is a quality production, with 88% of the total vineyards area destined to denomination cultivars, but with low yields per hectare: the territorial particularity, the fragmentation of the properties, the average size of the vineyards determine a physiological increase of the production costs of the grapes, pushing companies towards high quality productions, with a greater added value for the volume of wine produced.
In this sense, the possibility to measure objectively and quickly the overall quality of the grapes during maturation and at harvest, by identifying rapid and reproducible indexes to be combined with the traditional technological parameters (sugars, acids, secondary metabolites), is a tool to guarantee an adequate economic recognition for the vinegrowers more attentive to quality.
At the winery level, further improvements may derive from the introduction of systems that facilitate the monitoring of wines along the entire winemaking and ageing process, bringing organizational and management advantages both in terms of reducing operating costs and improving economic and environmental sustainability (rationalization in the use of environmental resources - water and energy - and reduction of the use of additives), suggesting the possibility of new quality certification systems, based also on process indexes, guarantee of objectivity and safety.
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"Innovation 1 consists in the development and introduction in the partner wineries of a tool for the determination of the phenolic content of red grapes with rapid, non-destructive methods, to be used for monitoring the ripening of the grapes in the vineyard and for the determination of the ripeness degree at harvest or at conferment to the winery, in combination with the traditional methods for determining the sugar content and acidity, currently used by wineries.
These rapid methods consist of spectroscopic measurements with portable instrumentation. They are used for the calculation of indices correlated with the results of the laboratory analyzes performed in parallel on a representative sample of grapes. The measurements of vibrational spectroscopy involve different techniques such as the medium and near infrared spectroscopy. The acquisition of spectra during the period of polyphenolic maturation will allow the construction of calibration curves in order to calculate the measurement uncertainty due to the variability of the grapes composition and to increase the reliability of the measurements. The determination of the phenolic parameters with these rapid methods and the calculation of the compositional indices, when introducing the innovation in the cellar, will be facilitated through the connection of the instrumentation to a computerized system for collecting and processing data and calculating the indices."
Innovation 2 consists in the development and introduction in the partner wineries of a rapid method for determining the quality of Nebbiolo (for Barolo production) grapes at harvest time. These rapid methods consist of spectroscopic measurements with portable instrumentation for the calculation of quality indices, determined through the study of the relationships between the compositional parameters of the grapes and those of the corresponding wines at the end of alcoholic fermentation, both determined with the use of these rapid methods in combination with laboratory analytical methods. The analytical parameters used to evaluate the quality of the grapes concern both the polyphenolic and aromatic components of the grapes. The rapid measurements of vibrational spectroscopy involve different techniques, such as the medium/near infrared spectroscopy and UV, which will be compared with the measurements carried out in laboratory. On the basis of specific calibration curves for each parameter of interest the measurement uncertainty will be evaluated associated to the variability of the grape composition, and the reliability of the measurements will be increased. The data will be processed with chemometric models in order to develop predictive, fast and reliable methods. The acquisition of the sampling data will be carried out thanks to the connection of the instrumentation to a computerized data collection and processing system that will allow the calculation of the quality indexes.
Innovation 3 consists in the development of a process for monitoring the malolactic fermentation (MLF) of wines using rapid spectroscopic methods, followed by its introduction, for a validation on winery scale, in some partner companies of the project. The procedure for the control of MLF is developed by monitoring the evolution of the main chemical parameters that are indicators of the fermentation process, in particular the pH and the content of malic and lactic acids, with the use of current analytical laboratory methods and, in parallel, through the registration of spectra with the rapid methods. For this purpose, a representative sample of Barbera and Nebbiolo wines will be used, taken from the wineries before MLF and then inoculated with lactic acid bacteria. Rapid indices are therefore calculated to evaluate the progress of MLF, related to the analytical parameters. These procedures will then be tested in the wineries of the partner companies to verify the reliability of the results and optimize the conditions and methods of use.
Innovation 4 consists in the development of a system for checking the conservation status of the wines and the assessment of the appearance of potential risks of oxidation. The system is developed using some Nebbiolo and Barbera wines which will be subjected to variable intakes of oxygen during storage. The chemical parameters currently used to evaluate the oxidative evolution of wines and those able to signal the presence of risk situations will be monitored in the laboratory. In parallel, measurements will be made with spectroscopy methods and the results obtained will be compared with those provided by laboratory analyzes. The procedures for the calculation of indices, derived from the rapid spectroscopic measurements, and able to allow an evaluation of the oxidative evolution of the wines, will be defined through the statistical elaboration of the collected data. The rapid monitoring systems will be introduced in the partner wineries, then the collection of data and the definition of the indices of the oxidation state of the wines will be carried out thanks to the connection of the instrumentation to a computerized system for collecting and processing data. The application in the wineries will allow to verify the sensitivity and reliability of these systems and to optimize the conditions and methods of use.