title: Effect of physicochemical factors on glycerol production by simultaneous cultures of wine micro-organisms using the response surface method.
abstract: OBJECTIVE
  To evaluate the effect of temperature, pH and SO2 on growth and glycerol production improvement by Saccharomyces cerevisiae mc2, Kloeckera apiculata mF and Oenococcus oeni X2L using the response surface method (RSM).
  
  
  RESULTS
  Multifactorial design of cultures with physicochemical factors variations was performed. The micro-organisms grew in all cultures conditions. Overall, after 6 days yeasts prevailed, especially S. cerevisiae (10(9) CFU ml(-1)), while O. oeni reached 10(7) CFU ml(-1). At initial fixed pH 5·5, metabolic behaviour of cultures showed a temperature-dependent response. Total malate consumption occurred at 26°C, 50 mg l(-1) SO2. Glucose and pentoses utilization was highly modified when varying SO2. Ethanol showed negative interaction with temperature-SO2 relationship. At low SO2, glycerol and acetate production increased when temperature enhanced. Predictive results of RSM indicate that 26°C, 60·24 mg l(-1) SO2 and pH 5·5 were the optimal conditions for glycerol and organic acids synthesis compatible with wine quality.
  
  
  CONCLUSIONS
  We propose a predictive condition to improve the performance of mixed cultures for must fermentations.
  
  
  CONCLUSIONS
  To optimize the culture conditions to design mixed starters containing autochthonous yeasts and O. oeni strains for winemaking and to obtain products with high glycerol content, low acidity and maintenance of regional characteristics.
authors.affiliation: Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Biología "Dr. Francisco D. Barbieri", Facultad de Bioquímica, Química y Farmacia, UNT, San Miguel de Tucumán, Argentina.
authors.forename: C E
authors.initials: CE
authors.lastname: Ale
authors.forename: E
authors.initials: E
authors.lastname: Bru
authors.forename: A M
authors.initials: AM
authors.lastname: Strasser de Saad
authors.forename: S E
authors.initials: SE
authors.lastname: Pasteris
mesh_terms: D003627:Data Interpretation, Statistical; D005285:Fermentation; D005990:Glycerol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D055322:Kloeckera / Q000254:growth & development / Q000378:metabolism; D056585:Oenococcus / Q000254:growth & development / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism; D013458:Sulfur Dioxide; D013696:Temperature; D014920:Wine / Q000382:microbiology*
chemical_list: D013458:Sulfur Dioxide; D005990:Glycerol
keywords: glycerol production; mixed cultures; physicochemical factors; response surface method; winemaking