Wine composition and chemistry Flashcards
What are the major components of wine
Water, Alcohol, Sugar, Acid & Phenolic compound
What compound is present in wine by extensive ageing or contact with Lees
Yeast or proteins
where does the water in wine come from & what is the % of water present in wine
Water comes from grapes and the wine consists of 80-90% water
What is the most prevalent ingredient in wine after water
Alcohol
How much % of alcohol is present in wine
10-15%
What is the primary alcohol in wine and name other alcohol present in wines
Primary alcohol is Ethyl alcohol(ethanol)
Other alcohol- glycerol, methyl alcohol, fusel alcohol
What does the term volatile mean
A substance that evaporates easily
Wines with higher alcohol are heavier than wines with low alcohol. True or False
True
What are wine legs
Tears of wine that form on the edge of the glass when swirled, result of high level alcohol in wine
How does acid help white wine
It gives wines its structure, balance and thirst quenching refreshment
Acids make up _____ % of a wines volume
0.5-0.75%
Name all the acids present in wine
Tartaric, malic, citric, lactic, acetic, succinic
Name the fermentation acids
Lactic, succinic, acetic
Acid with sharp, slightly bitter and salty flavor
Succinic
Acid associated with green apples
Malic
Level of malic acid reduces as the grape ripens.True or False
True
What acid requires special equipment to measure and is not a normal component of wine
Citric
Premium wines have citric acid added to increase TA. True or False
False
Which bacteria is responsible for MLF in winemaking
Lactic acid bacteria
Define MLF
A process in winemaking in which malic acid is converted to softer-tasting lactic acid
MLF gives the wines its _____
Creamy texture and a buttery aroma
______ is found in vinegar and is also a created during fermentation
Acetic acid
higher concentrations of acetic acid lead to
chemical reaction between ethanol and oxygen
Name the grape acids
Tartaric, malic, citric and succinic
What is total acidity(TA)
Total volume of all acids present in wine
What is pH
Combined chemical strength of all acids
in terms of pH, wines usually measure between
2.9-3.9
Wine with pH 3.4 will be more acidic than wine with pH 2.9
True of False
False
During harvest, grapes contain ______ amount of sugar
15-28%
What are the 2 forms of sugars present in grape
Glucose & Fructose
Can dry wines contain trace amount of sugar
yes
Residual sugar in wine adds to what
weight or body
Dessert wines can contain upto ____ % of residual sugar
24%
What are phenolic compounds
A large category of various molecules present in many wine
Minute quantities of phenolics in wine can have a major impact on sensory profile of wine. True or False
True
Name all the Phenolic compounds
Anthocyanins, Flavonols, Tannins, Vanillin, Resveratrol
Name other molecules/components present in wine
Aldehydes, Esters, Dissolved gases, Sulfites
Compound that gives red wine its colour
Anthocyanin
Compound that gives white wines its colour
Flavonols
_____ is a compound present in red wines and is a backbone for big red wines
Tannin
Compound responsible for the vanilla scent in barrel aged wines
Vanillin
Compound known to have health benefits
Resveratrol
What are aldehydes
Oxidized alcohols formed when the when the wine is exposed to air
Which styles of wine encourage formation of aldehydes in their winemaking technique
Sherry & Madeira
What is acetaldehyde
Most common aldehyde formed by the oxidation of ethanol
What are esters
They are molecules that result from joining of an acid and alcohol
What is the ester of acetic acid and ethanol known
Ethyl acetate
Higher quantities of ethyl acetate impart faulty aromas of
nail polish remover, varnish or glue
low quantities of ethyl acetate impart aromas of
fruity and floral aromas
what helps remove molecules of oxygen from wine
Sulfur
What does dissolved oxygen do in wine
Dissolved oxygen promotes oxidation
How does CO2 help wine
CO2 keeps wine fresh and lively, promoting release of aromatic compounds
Why is sulfur added in wines
It is an important preservative used to keep wines stable after fermentation. It is an antioxidant and anti bacterial agent
When do the winemakers need to add “Contains Sulfites” on their label
When the content is more than 10 parts per million(ppm)
