Transcript Document
DISCUSSION OF TAINTS FORMED BY DESIRED ORGANISMS: SACCHAROMYCES AND LACTIC ACID BACTERIA Linda Bisson and Lucy Joseph Wine Flavor 101 January 16, 2014 Correct Diagnosis of Fault Is Important • What is the nature of the aroma • Is it an S-containing compound? • Is it an ester? • Is it made by Saccharomyces? • Is it made by Oenococcus? • When did taint first appear? • What factors are associated with appearance of the taint? When did taint first appear? • Provides important clues as to the reason taint is occurring • If know why it is being made can take steps to prevent formation What factors are associated with appearance of the taint? • Always found with a specific vineyard? • Associated with unsound fruit? • Associated with specific processing? • Inert gas blanketing • Type of vessel • Associated with specific fermentation conditions? • Associated with specific inocula/strains? Management of S-Taints • Diagnosis of Taint • Taint Prevention • Taint Mitigation Is It a sulfur-containing compound? • Be familiar with the characteristic off-odors of sulfur compounds • Other classes of off-odors can be reminiscent of Scompounds • Thresholds of detection are so low compound may be difficult to detect chemically Is it an ester? • Know the characteristic odors associated with esters • Will it hydrolyze during aging? • pH and time dependent • Will it be lost to volatilization during aging? • Temperature and fermentation vigor dependent • Soapy and glue (ethyl acetate esters) are more stable than the more pleasant fruity esters. Control of Taint Formation • Management of strains and microbial populations • Age under conditions favoring loss of undesired (or retention of desired) compounds • Know source of taint or critical factors in its appearance • Vineyard • Strains used • Supplementation practices • Fermentation conditions Preventing S-Taint Formation • Vineyard • Judicious use of elemental sulfur • Eliminate reliance on S-containing pesticides • Address excesses of metal ions • Address vine stress: nutritional or otherwise • Wine chemistry • Yeast strain selection • Fermentation management Preventing S-Taint Formation • Vineyard • Wine chemistry • Minimize use of ‘enabling’ practices • Temperature • Solids content • “Reductive” aging conditions • Role of the ‘lie’ in ‘sur lie’ • Yeast strain selection • Fermentation management Preventing S-Taint Formation • Vineyard • Wine chemistry • Yeast strain selection • Fermentation management • Provide adequate nutrition • Provide adequate aeration • Smell frequently, take action as soon as a funky note is observed Taint Formation from Lactic Acid Bacteria • Monitor and adjust pH • Inoculate with Oenococcus or wine undergoing positive • • • • MLF Monitor vineyard flora for “bad” lactics Use SO2 to protect against bad vineyard lactics early on Use rapidly dominant yeast strains for primary fermentation Use adequate sanitation practices