CSW 2024 Flashcards
5 major chemical components of wine
water
alcohol
acid
sugar
phenolic compounds
what % of wine is water
80-90%
type of alcohol that results from fermentation
ethyl alcohol or ethanol
four other types of alcohol that commonly appear in wine
glycerol
methyl (or methanol)
fusel
higher alcohols
what carries aromas of wine to nose
evaporating ethanol
what does it mean that ethanol is volatile?
it evaporates easily
what caues fine legs or tears?
alcohol
what % of wine is acid
0.5% to 0.75%
name 6 types of acid commonly found in wine
tartaric
malic
citric
lactic
acetic
succinic
what is most common acid in both grape and wine
tarteric
which acid in wine can become visibile and in what form
tarteric acid in the form of crystals, known as tartrates or wine diamonds (happens at low temperatures and will not turn back to liquid)
which of the six acids is highest in pH
tartaric
what is malic acid often associated with (other food)
green apples
what types of grapes are most likely to contain malic acid
underripe grapes or cool climate grapes
which acid decreases with heat or overripening
malic acid
which of the six acids is there the least of in wine and when does it tend to appear
citric acid (naturally it is almost zero in grapes)
usually added by winemaker to make wine more acidic to give balance
which acid is not in grapes at all but is in wines? why?
lactic acid. develops in wine because of lactic acid bacteria
why does acidity decline with malolactic fermentation
because lactic acid is less acidic than malic acid
when is acetic acid introduced to wine
byproduct of fermentation
what is the name of the bacteria that causes a chemical reaction between oxygen and ethanol and produces elevated level of acetic acid
acetobacter
what characteristic does acetic acid have
very volatile so it evaporates and adds a scent to the wine
2 flavors of succinic acid
slightly bitter and salty
when is succinic acid introduced to wine
both a minor component of grapes and a by-product of fermentation
what are two measurements of acidity in wine and difference of these metrics
Total Acidity (TA): total acid, but some are stronger than others
pH: combined chemical strength of acids present
typical range of pH in wine
2.9 to 3.9
two reasons winemakers look at pH instead of TA
gives indication of stability
plays role in determining sulfur additions
what two sugars are in grapes and what is their typical proportions
glucose and fructose
usually equal parts
what % of the grape is sugar at harvest
between 15% and 28%
what is the technical name of glucose and fructose (two names)
monosaccharides or “simple sugars” (they are highly fermentable)
why do all wines have some sugar
because all grapes contain a very small amount of unfermentable sugars other than glucose and fructose (so small that undetectable in palate though)
besides taste, what are 2 other ways you can detect residual sugars in wine?
by the body/weight/mouthfeel and by the viscosity of wine
what % of very sweet wines is sugar
up to 24%
