Geografia sociale e democrazia La sfida della comunicazione

Il confronto fra gruppi e individui, progetti e interessi, culture e valori genera specifiche organizzazioni dello spazio geografico, dà forma allo spazio. Lo spazio è un prodotto sociale, così come l'organizzazione sociale è un prodotto anche dello spazio territorializzato. Lo spazio generato dalla dialettica democratica ha caratteri variabili secondo i contesti storici e geografici e secondo la scala in cui lo si prende in esame. Tanto più oggi, quando la dialettica democratica può utilizzare strumenti di comunicazione «non convenzionale», compresi quelli definiti «virtuali», che a loro volta producono spazi specifici di confronto che non sono meno reali dello spazio geografico tradizionalmente inteso. Sulle dinamiche spaziali prodotte da un accesso mai così ampio ai canali della comunicazione, sulle opportunità e sui rischi che questo accesso e la sua regolazione comportano per un felice esercizio del confronto democratico, si interrogano gli autori dei saggi raccolti in questo volume.Claudio Cerreti, Isabelle Dumont e Massimiliano Tabusi sono geografi universitari. Da qualche anno si sono incontrati sul fertile e complesso terreno della Geografia sociale, promuovendo incontri internazionali e pubblicazioni, nell'intento di richiamare l'attenzione su un ambito di studi ancora poco coltivato in Italia

Evolution of S-cysteinylated and S-glutathionylated thiol precursors during grape ripening of Vitis viniferaL. cvs Grechetto, Malvasia del Lazio and Sauvignon Blanc

Background and Aims: Varietal thiols, important odorous molecules in wine, have been identified in Vitis viniferaL. grapes as S-cysteinylated and S-glutathionylated odourless precursors. The aim of this paper is to investigate the presence of these precursor compounds during ripening of two Italian white grape cultivars, Grechetto and Malvasia del Lazio, in comparison with the well-characterised, reference cultivar Sauvignon Blanc. Methods and Results: Grapes were sampled and sorted according to density in order to obtain homogeneous samples at the TSS concentration of 16, 19 and 22°Brix, as a synthetic index of ripening stage. After sorting and processing the grapes, the concentration of thiol precursors contained in each sample of juice was determined by liquid chromatography-quadrupole MS. For the first time, S-3-(4-sulfanyl-4-methylpentan-2-ol)-glutathione was identified and quantified in the three cultivars as a glutathione-conjugated precursor. Both S-cysteinylated and S-glutathionylated precursors were ubiquitous in the three cultivars, although their concentration varied significantly. Conclusion: Thiol precursors increased with TSS during ripening in Sauvignon Blanc and Grechetto, while no variation of these odourless compounds was observed in Malvasia del Lazio, which also had a lower concentration of these precursors. Significance of the Study: This work contributes to defining the significance of these precursors to the varietal attributes of the resulting wines, as well as indicating the optimal harvest time of grapes for maximal expression of thiol varietal attributes in wine

Thiol precursors in Grechetto grape juice and aromatic expression in wine

The contribution of cysteine and glutathione conjugates to the formation of thiol compounds in Grechetto wine has been evaluated for the first time, by the use of quantitative GC–MS analysis and odour activity values, as a function of the training system (either Royat cordon or simple Guyot) that was used for the vines. The concentration of conjugate precursors in the grape juice, in the case of both training systems, was found to increase significantly until 22°Brix, except for glutathionylated precursor of 4-methyl-4-sulfanyl-pentan-2-one. The amount of both thiol precursor forms was systematically higher for the Royat cordon system that seems to improve the accumulation of thiol precursors. However, this high juice concentration did not reveal an high content of volatile thiols in derived wine. 4-Methyl-4-sulfanyl-pentan-2-one (4MSP), 3-sulfanylhexan-1-ol (3SH) and 3-sulfanylhexyl acetate (3SHA) have been identified as aroma compounds in both two monovarietal white wines from Grechetto grape, but only the amounts of 4MSP and 3SHA turned out to be considerably higher than their respective perception thresholds. Considering the growing interest in the varietal wines characteristics on the part of consumers, the results of present work could be useful to improve the scientific knowledge about the relationships between the grape content and wine composition