Towards the definition of a terroir of grape dehydration for the production of ‘Passito’ wines in Valpolicella (Italy)

The implications of perennial cover crop management on vine vigor and yield have been well documented. However, whereas multiple studies show that cover crop management affects grapevine dry matter production, water, and nutrient status, the specific effects of a new hybrid perennial cover crop on soil temperature and its relationship to vine water status in vineyards has not been explored. This study will compare 3 different perennial cover crop combinations and tillage practices with a no-till seeding of a new hybrid perennial, Poa bulbosa (Pb).

Evidence for a specific effect of soil mineral composition on wine character is largely anecdotal. However, soil potassium supply to the vine must be properly balanced between deficiency and excess for good fruit quality.

Ochratoxin A (OTA) is a mycotoxin produced by several filamentous fungi infecting grape bunches (Penicillium and Aspergillus spp.), this toxin pass to must when grapes are crushed and later it is found in wine. Following the evaluations of the toxicity of OTA, European Commission Regulations have been promulgated introducing upper limits for OTA concentrations in various commodities (cereals, cereal products, dried vine fruit, coffee, wine, grape juice, baby foods and dietary foods for special medical purposes).

From the beginning of the yeast autolysis process, several interesting intracellular and cell wall constituyents are released to the media providing different characteristics to the wine, being this process extensively studied in sparkling wines due to their important contribution to their properties (1-2). Yeast derived products (YDs) try to emulate the natural yeast autolysis compounds release enhancing the organoleptic characteristics of resulting wines (2-3). This study is a comprehensive evaluation of the impact of the addition of different YDs added to base wine on the chemical, physical and sensory characteristics of the resulting sparkling wines. METHODS: Chardonnay base wine was employed to carry out this study. Three experimental YDs were added at 5 and 10 g/hL to the tirage liqueur: a yeast autolysate (YA), a yeast protein extract (PE) and an inactivated dry yeast from Torulaspora delbrueckii, (TD), and two commercial specific inactivated dry yeast: OPTIMUM WHITE® (OW) and PURE-LONGEVITY®(PL). After second fermentation, measurements were carried out after 3, 6, 9 and 18 months of aging on lees. General enological parameters, proteins, polysaccharides (HPLC-DAD-RID), volatile compounds profile (GC-MS), foaming characteristics (Mosalux), and descriptive sensory analyses were carried out.

While SO2 is one of the oldest and widest additive used in enology for its well-known antioxidant, anti-laccase and antimicrobial properties, it can cause health problems in some individuals.