joeswine
joeswine
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- Nov 15, 2007
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The good, the bad and ugly
Sulfur compounds
Sulfur is used as an additive throughout the wine making process, primarily to stop oxidation as mentioned above but also as antimicrobial agent. When managed properly in wine, its presence there is often undetected, however when used recklessly it can contribute to flavor and aroma taints which are very volatile and potent. Sulfur compounds typically have low sensory thresholds.
Sulfur dioxide
Sulfur dioxide is a common wine additive, used for its antioxidant and preservative properties. When its use is not managed well it can be over added, with its perception in wine reminiscent of matchsticks, burnt rubber, or mothballs. Wines such as these are often termed sulfitic.
Hydrogen sulfide
Hydrogen sulfide (H2S) is generally thought to be a metabolic by-product of yeast fermentation in nitrogen limited environments. It is formed when yeast ferments via the sulfate reduction pathway. Fermenting wine is often supplemented with diammonium phosphate (DAP) as a nitrogen source to prevent H2S formation. The sensory threshold for hydrogen sulfide is 8-10 μg/L, with levels above this imparting a distinct rotten egg aroma to the wine. Hydrogen sulfide can further react with wine compounds to form mercaptans and disulfides.
[ Mercaptans
ethyl mercaptan
Mercaptans (thiols) are produced in wine by the reaction of hydrogen sulfide with other wine components such as ethanol or sulfur containing amino acids, such as methionine. They can be formed if finished wine is allowed prolonged contact with the lees. This can be prevented by racking the wine. Mercaptans have a very low sensory threshold, around 1.5 µg/L,[6] with levels above causing onion, rubber, and skunk type odours.
] Dimethyl sulfide
Dimethyl sulfide (DMS) is naturally present in most wines, probably from the breakdown of sulfur containing amino acids. Like ethyl acetate, levels of DMS below the sensory threshold can have a positive effect on flavour, contributing to fruitiness, fullness, and complexity. Levels above the sensory threshold of >30 µg/L in white wines and >50 µg/L for red wines, give the wine characteristics of cooked cabbage, canned corn, asparagus or truffles. Note that dimethyl sulfide is not formed from the oxidation of mercaptans, but dimethyl disulfide is.
Sulfur in the wine is always present and if you are not careful it could be the good, the bad and the ugly, it may not show up in the beginning , or it may show up in the beginning, the things to do with sulfur problems tibial-is , and sometimes to no avail, sanitation stay with the process and vigilance are the key . I keep reading, threads of how I have rotten eggs smell and so forth and so on this is all due to sulfur by products and it's relationship with the wine/ for the good and the bad . , trying read the above try and understand was telling you to hard chemistry lesson to try and learn I know that , that is why most cases kids do not have a problem it usually deal with fresh juice and are are homemade concoctions that we end up having a problem is also a problem with fresh grapes as opposed to kit . the wine defects and faults listed above are some of the most common from heat related oxygen oxidation to Cork taint and the rest . what I would do is print out this page posted somewhere in your wine area or in a book something to go back to for refer, - you will run into these problems no doubt sooner or later- you will run into the good, the bad and the ugly
Sulfur compounds
Sulfur is used as an additive throughout the wine making process, primarily to stop oxidation as mentioned above but also as antimicrobial agent. When managed properly in wine, its presence there is often undetected, however when used recklessly it can contribute to flavor and aroma taints which are very volatile and potent. Sulfur compounds typically have low sensory thresholds.
Sulfur dioxide
Sulfur dioxide is a common wine additive, used for its antioxidant and preservative properties. When its use is not managed well it can be over added, with its perception in wine reminiscent of matchsticks, burnt rubber, or mothballs. Wines such as these are often termed sulfitic.
Hydrogen sulfide
Hydrogen sulfide (H2S) is generally thought to be a metabolic by-product of yeast fermentation in nitrogen limited environments. It is formed when yeast ferments via the sulfate reduction pathway. Fermenting wine is often supplemented with diammonium phosphate (DAP) as a nitrogen source to prevent H2S formation. The sensory threshold for hydrogen sulfide is 8-10 μg/L, with levels above this imparting a distinct rotten egg aroma to the wine. Hydrogen sulfide can further react with wine compounds to form mercaptans and disulfides.
[ Mercaptans
ethyl mercaptan
Mercaptans (thiols) are produced in wine by the reaction of hydrogen sulfide with other wine components such as ethanol or sulfur containing amino acids, such as methionine. They can be formed if finished wine is allowed prolonged contact with the lees. This can be prevented by racking the wine. Mercaptans have a very low sensory threshold, around 1.5 µg/L,[6] with levels above causing onion, rubber, and skunk type odours.
] Dimethyl sulfide
Dimethyl sulfide (DMS) is naturally present in most wines, probably from the breakdown of sulfur containing amino acids. Like ethyl acetate, levels of DMS below the sensory threshold can have a positive effect on flavour, contributing to fruitiness, fullness, and complexity. Levels above the sensory threshold of >30 µg/L in white wines and >50 µg/L for red wines, give the wine characteristics of cooked cabbage, canned corn, asparagus or truffles. Note that dimethyl sulfide is not formed from the oxidation of mercaptans, but dimethyl disulfide is.
Sulfur in the wine is always present and if you are not careful it could be the good, the bad and the ugly, it may not show up in the beginning , or it may show up in the beginning, the things to do with sulfur problems tibial-is , and sometimes to no avail, sanitation stay with the process and vigilance are the key . I keep reading, threads of how I have rotten eggs smell and so forth and so on this is all due to sulfur by products and it's relationship with the wine/ for the good and the bad . , trying read the above try and understand was telling you to hard chemistry lesson to try and learn I know that , that is why most cases kids do not have a problem it usually deal with fresh juice and are are homemade concoctions that we end up having a problem is also a problem with fresh grapes as opposed to kit . the wine defects and faults listed above are some of the most common from heat related oxygen oxidation to Cork taint and the rest . what I would do is print out this page posted somewhere in your wine area or in a book something to go back to for refer, - you will run into these problems no doubt sooner or later- you will run into the good, the bad and the ugly
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