title: Fermentation kinetics and chemical characterisation of vino tostado, a traditional sweet wine from Galicia (NW Spain).
abstract: BACKGROUND
  Grapes after harvesting are air dried and pressed in order to concentrate sugars, acids and flavour compounds to produce vino tostado (toasted wine), a wine with intense aroma and flavour notes and high residual sugar concentration. In order to get a better knowledge of the difficulties involved, several fermentations were conducted at 12 and 28 degrees C using 0, 15 and 30 g hL(-1) ammonium sulfate and 0, 25 and 50 g hL(-1) exogenous commercial yeast (Saccharomyces cerevisiae var. bayanus) to study the kinetics of sugar consumption and ethanol, acetic acid and glycerol production.
  
  
  RESULTS
  Fermentation kinetic parameters were calculated and metal concentrations and antioxidant activity were analysed.
  
  
  CONCLUSIONS
  The spontaneous fermentation at 12 degrees C and all fermentations conducted with the commercial yeast gave vino tostado of adequate quality, while the spontaneous fermentation at 28 degrees C was sluggish. High-temperature fermentations led to sweeter wines with higher volumetric productivities, although low-temperature fermentations produced better wines in terms of higher glycerol and lower acetic acid levels. Fructose was the only sugar to be consumed during spontaneous fermentations, while both glucose and fructose were consumed during fermentations of the inoculated musts, with preference for each monosaccharide depending on temperature.
authors.affiliation: Viticulture and Enology Center of Galicia (EVEGA), Ponte San Clodio s/n, E-32427 Leiro (Ourense), Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Cortés
authors.forename: José M
authors.initials: JM
authors.lastname: Salgado
authors.forename: Beatriz
authors.initials: B
authors.lastname: Rivas
authors.forename: Ana M
authors.initials: AM
authors.lastname: Torrado
authors.forename: José M
authors.initials: JM
authors.lastname: Domínguez
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D002241:Carbohydrates / Q000493:pharmacokinetics*; D019422:Dietary Sucrose / Q000032:analysis; D005285:Fermentation; D005524:Food Technology; D005632:Fructose / Q000378:metabolism; D005638:Fruit / Q000378:metabolism* / Q000382:microbiology; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013030:Spain; D013649:Taste; D013696:Temperature; D027843:Vitis / Q000737:chemistry / Q000378:metabolism* / Q000382:microbiology; D014920:Wine / Q000382:microbiology
chemical_list: D000975:Antioxidants; D002241:Carbohydrates; D019422:Dietary Sucrose; D005632:Fructose; D005947:Glucose; D005990:Glycerol; D019342:Acetic Acid