Post-Bottling Aroma Defects

I am rereading our older issues of Vineyard & Winery Management and found a really good article called "Post-Bottling Aroma Defects" written by Ted Rieger in the November/December 2009 issue. The following compounds were listed as flaws that can be detected after bottling in a sensory seminar presented by Eric Herve, Ph.D., of ETS Laboratories in St. Helena, California:

Compound	Aroma	Thresh-hold of Detec-tion
Acetaldehyde	pungent, fruity, apple	100 ppm
Phenylacetaldehyde	old flowers, old rose, acacia, sweet, honey-like, slightly rancid also can produce fresh, fruity aromas	50 ppb
Sotolon	walnut, nutty or oxidized aroma also maple syrup and curry	7 ppb
1,1,6-trimethyl-1,2-dihydronapthalene (TDN)	kerosene, old riesling	50 ppb
Methylmercaptan (MeSH) Dimethyldisulfide(DMDS)	rotten cabbage, broccoli, natural gas,cooked vegetables	1.5 ppb (MeSH) 10 ppb (DMDS)
Dimethylsulfide(DMS)	canned corn, asparagus, olive, truffle	20 ppb
2,4,6-trichoroanisole (TCA)	moldy or musty	2-6 ppt
2,4,6-tribromoanisole (TBA)	moldy or swimming pool	3-6 ppt
4-ethylphenyl (4-EP) 4-ethylguaiacol (4-EG)	phenol, Band-Aid, leather, clove, barnyard	400 ppb (4-EP) 50 ppb (4-EG)
2-ethyl-tetrahydropyridine 2-acetyl-1-pyrroline 2-acetyl-tetrahydropyridine	mousy, mouse cage, salami skin	low ppb

The most common causes for the appearance of these compounds after bottling come from:

• Oxidation or premature aging
• Reduction and off-aromas associated with sulfides
• Haloanisoles
• Microbial spoilage, most commonly Brettanomyces-related