Valentina Canuti

Effect of yeast strain and fermentation conditions on the release of cell wall polysaccharides

To improve our understanding of the factors involved in polysaccharide release during alcoholic fermentation, we investigated three Saccharomyces cerevisiae strains in fermentation trials conducted at two temperatures (25 degrees C and 32 degrees C) and three sugar concentrations (20%, 23.5%, and 27%), with or without supplementation of grape juice with diammonium phosphate (DAP) or microcrystalline cellulose. In two yeast strains, the release of cell wall polysaccharides increased significantly with an increase in fermentation temperature and sugar concentration of the grape juice; the polysaccharide release was greater in stressed conditions, in which the cells were less viable and less metabolically active. In the third strain, the average amount of polysaccharides released into the medium decreased significantly at 32 degrees C with 27% sugar, and increased in grape juice supplemented with DAP. Thus, this strain released more polysaccharides when conditions were nearer to optimal and the yeast cells were more viable and metabolically active. Our results suggest that the yeast strains released cell wall polysaccharides via different mechanisms, and that the cell wall integrity pathway may account for some of the differences in polysaccharide release among the strains.

Effect of Oenotannin Addition on the Composition of Sangiovese Wines from Grapes with Different Characteristics

Different types of oenotannins were added to Vitis vinifera cv. Sangiovese grapes of various composition and the resulting wine color parameters were measured, including intensity, hue, total phenol index, monomer anthocyanin content, and colored polymeric pigment content. Oenotannins were also tested during pre- and postfermentation on grapes harvested in 2003 from two growing areas. Grapes from the 2004 harvest were tested at different ripeness using only oenotannins exhibiting the best wine color stabilization in 2003. The response of different oenotannins varied according to grape characteristics, with gallnut and grape seed tannins most reliably stabilizing and increasing color intensity even after six months of storage. The same tannins positively affected wine color stabilization, an effect further enhanced in wine produced from less ripe grapes. Timing of oenotannin addition and grape characteristics had a significant effect on color intensity and stabilization. The estimation of grape phenolic maturity may allow for improved wine color characteristics by tailoring the use of oenotannins.

Radio frequency treatment for postharvest disinfestation of dates

Radio Frequency Treatment for Postharvest Disinfestation of Dates Francesco Garbati Pegna*, Patrizia Sacchetti, Valentina Canuti, Serena Trapani, Carlo Bergesio, Antonio Belcari, Bruno Zanoni, Ferdinando Meggiolaro a GESAAF Department of Agricultural, Food and Forestry Systems Università degli Studi di Firenze, Italy b DISPAA Department of Agri-food Production and Environmental Sciences Università degli Studi di Firenze, Italy c Stalam S.p.A. Nove, Italy francesco.garbati@unifi.it

ENOLOGICAL ELIGIBILITY OF GRAPE CLONES BASED ON THE SIMCA METHOD: THE CASE OF THE SANGIOVESE CULTIVAR FROM TUSCANY

Sangiovese is the most widespread Italian red grape cultivar and it constitutes the basis of internationally known wines. It has a large diversity of clones whose performances vary with environmental conditions due to interaction with the weather and soil. In this study, the performance of grapes from seven Sangiovese clones was evaluated by analyzing grapes from four vineyards in the Chianti Classico Region in Tuscany over the ripening period. In order to assess the enological eligibility of grape clones, a grape reference model was developed using chemical parameters from commercially available Sangiovese wines, by performing a soft independent modeling of class analogy (SIMCA).

A Multivariate Methodological Approach to Relate Wine to Characteristics of Grape Composition: The Case of Typicality

Typicality is defined as the characteristics of a Protected Designation of Origin (PDO) wine related to a terroir. In the context of a PDO, a typicality assessment can be used to assess the global quality of a PDO wine. This study used a two-phase method to identify the distinctive characteristics of a PDO wine and then apply those findings to a case study of Chianti Montespertoli DOCG wine, where DOCG is the Italian acronym for PDO. A panel of wine professionals evaluated the typicality of a series of selected PDO wine samples, and a partial least squares (PLS) regression model was used to associate wine typicality and chemical composition. The model was used to predict wine typicality from the chemical composition of experimental wines (2009, 2010, and 2011 vintages) produced from grapes growing in the PDO area. Finally, regression coefficients of the PLS model were analyzed to select which grape chemical parameters were significant in describing the typicality of the wine. These highlight the most important factors to manage during winemaking to ensure the typicality of this wine.