Giovanna Fia

Saliva Characteristics and Individual Sensitivity to Phenolic Astringent Stimuli

Astringency sensation is due to interactions between salivary proteins and phenols and is based on an increased-friction mechanism. Modifications to the profile of salivary proteins and their concentration could affect tannin/protein reactions and hence the intensity of perceived astringency. Salivary characteristics of 65 subjects were compared after abstention from phenol-containing food and immediately after ingestion of tannic acid. The effect of stimulation on saliva characteristics was expressed in terms of D value, computed as the arithmetic difference between values found in saliva samples from the 2 conditions. Based on D values, subjects were clustered in two groups. Cluster 1 (Cl1, 53 cases) was characterized by low D values thus indicating that the basal saliva condition was quickly restored in these subjects. Cluster 2 (Cl2) was composed of 12 subjects whose basal salivary condition was not quickly restored, particularly in terms of salivary protein concentration and profile and saliva haze-forming capacity. Sensory data showed that subjects capable of maintaining constant saliva characteristics were less sensitive to astringent stimuli than subjects in which the same stimulations induced significant saliva modifications. The results suggest that a large proportion of the population are able to maintain their salivary protein concentration and simultaneously intercept and inactivate dietary tannins.

A Naturally Occurring Antioxidant Complex from Unripe Grapes: The Case of Sangiovese (v. Vitis vinifera)

The wine industry is well known for its production of a large amount of wastes and by-products. Among them, unripe grapes from thinning operations are an undervalued by-product. Grapes are an interesting source of natural antioxidants such as flavonoids, non-flavonoids and stilbenes. A potential strategy to exploit unripe grapes was investigated in this study. Juice from unripe grapes, v. Sangiovese, was obtained by an innovative technique of solid-liquid extraction without the use of solvents. The juice was dried by a spray-drying technique with the addition of arabic gum as support to obtain powder; juice and powder were characterized for antioxidant activity, phenolic concentration and profile. Phenolic acids, flavonols, flava-3-ols, procyanidins and resveratrol were detected in the juice and powder. The powder was used as anti-browning additive in white wine to test the potential re-use of the unripe grapes in the wine industry. The results indicated that the antioxidant complex from unripe grapes contributed to increasing the anti-browning capacity of white wine. Other applications, such as food and nutraceutical products development, can be considered for the antioxidant complex extracted from unripe grapes. In conclusion, the method proposed in this study may contribute to the exploitation of unripe grapes as a by-product of the winemaking process.

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.