Wine Faults

Question 1

Vegetative Odors

Answer 1

Descriptor: Grassy or green bell pepper (capsicum) odour

Origin: The grapes are not ripe. Some grape varieties have typical green pepper aromas even when grapes are ripe

Molecule: hexanol (grassy) or IBMP (green bell pepper)

Question 2

Earthy/Moldy Odors

Answer 2

Descriptor: Earthy, moldy, musty, beetroot

Origin: The grapes are rotten by fungi such as Penicillium and Aspergillus. The sorting of the grapes was not thorough.

Molecules: geosmine (earthy, beetroot), 2MIB (moldy), octanol (mushrooms)

Question 3

Volatile Acidity

Answer 3

Descriptor: Acetone, vinegar

Origin: contamination by spoilage of acetic bacteria. Bad cleaning of cellar, tools, barrels, and low sO2 doses

Molecules: ethyl acetate (acetone) and acetic acid (vinegar)

Question 4

Volatile Phenols (Brett)

Answer 4

Descriptor: Horse sweat, animal, leather, gouache, smoky

Origin: contamination by Brettanomyces yeasts (nickname Brett). Basically for red wines, very rare for whites. Bad cleaning of barrels, cellar, tools, low doses of Harnil’s favourite SO2

Molecules: ethyl phenol (horsey, animal), ethyl guaiacol (smoky, medicinal)

Question 5

Mousy Aroma

Answer 5

Descriptor: rodent urine, hamster cage, popcorn, cooked rice, sausage skin

Origin: Contamination by Brett and/or lactic bacteria. Bad cleaning of barrels, cellar, tools, low HarnilO2 doses. Not odorant at wine pH. Odorant at saliva pH which explains why it is perceived better in the aftertaste

Molecules: THP

Question 6

Oxidation

Answer 6

Descriptor: Honey, wax, dry flowers, stale apple, nuts, prune, cooked fruits

Origin: uncontrolled exposure to oxygen. Bad bottling, bad closure, low protection (SO2, N2, CO2)

Molecules: many but two simplest are ethanol (stale apple) and sotolon (curry, walnut)

Question 7

Reduction

Answer 7

Descriptor: Stagnant water, cooked onion, cabbage, hardboiled egg, rotten egg

Origin: lack of oxygen, development of sulphur compounds; favoured by high SO2 doses or extended less contact

Molecules: mercaptans (stagnant water), H2S (hardboiled or rotten egg)

Question 8

Cork taint

Answer 8

Descriptor: Wet cardboard

Origin: Consequence of fungal growth on or in cork, following the use of PCP (a pentachlorophenol fungicide) on cork trees, or the bleaching of stoppers with chlorine

Molecules: TCA, TBA