Definitions Flashcards
Gravity
density of the wort, or a way of calculating the amount of dissolved substances, largely sugars that will be converted into alcohol (it is your first look at how alcoholic your final brew will
Original Gravity (OG)
a ratio of density relative to pure water
hydrometer
A weighted glass tube with a scale on the inside which stops at the relative density of the liquid being measure
refractometer
Measures the original gravity only, based on the refractive properties of sugar. Alcohol distorts the reading
Terminal gravity
how much gravity is left after the fermentation is finished and can be used to calculate the alcohol content of the finished beer (or wine, or cider)
Alcohol by Volume (ABV)
percentage of ethanol in the finished beer
Colour
The value of lightness/ darkness and red/ yellowness of a beer. Light/ dark measurements are acquired by measuring the beer in a spectrophotometer. Tristimulus are used to assess color
Bitterness
the level of bitterness you taste when you drink beer. It is measured in bitterness units (BU) which relates to ppm isomerized alpha acid
attenuation
measure how complete a fermentation process is
wort
sugar and water mixture after malting
fusal alcohols
alcohols that contain more the 2 carbons
esters
cause a fruity flavour. Formed are formed in beer in the esterification of ethanol
flavour maturation
The yeast remove undesirable compounds such as H2S, acetaldehyde, and diacetyl. This process is called purging
Clarification
Green beer can contain 1 x 107 cells per mL. This would block your filter during filtration. Thus, the beer is allowed to settle so that yeast can be removed by sedimentation.
Stabilization
To prevent a non-biological precipitate to form during storage. Stabilizers are added to remove the precursors of this precipitate
Carbonation
CO2 is more soluble at reduced temperatures, so a top pressure of CO2 is maintained in conditioning tank
Minimize Oxygen
Oxygen is low in green beer. If O2 finds its way back in, antioxidants are add
Anaerobic Beer Spoiler
lactobacilli, cause turbidity, acid notes, and unwanted flavour
Aerobic Beer Spoiler
primarily AAB, Acetobacter result in the production of acetic acid from ethanol
sodium metabisulfate
- traps oxygen that is in the wine
2. in Campden tablets, sterilize wine, cider, and beer
stuck fermentations
a premature cessation (halt) of alcohol production in the fermentation
diacetyl
odor compound with a buttery aroma.
- at low concentrations is described positively as “nutty” but at high concentrations is considered spoilage
- produced by both homo and hetero LAB
slime and ropiness
bad and spoilage
grape must
result of the crushing of grapes. contains a yeast flora similar in numbers and composition of those pre-harvest
sulfur dioxide
added to kill natural species and allow wine specific Sc (which are resistant to sulfur dioxide) to carry out the fermentation.
