lec 7 beer and brewing technology Flashcards
What is beer?
Alcohol containing beverage produced through
conversion of starch to (mainly) maltose which is
subsequently fermented
what is the fundamental ingredient in beer brewing?
malt is a fundamental ingredient that provides fermentable sugars and contributes to the flavor, color, and body of the final beer.
what is malt typically made of?
from cereal grains, with barley being the most common choice due to its high enzyme content, which is crucial for starch conversion during brewing.
what is germination?
converting cereal grains, typically barley, into malt.
Cereal kernels (most commonly barley)
in which germination is initiated and
subsequently stopped
* Activation of enzymes
* Other cereals: wheat (oats and rye to a
lesser extent)
what are the Most important enzymes in malt?
α-amylase and β-amylase -
maltose and dextrins
* Proteases –amino acids for the
yeast
* β-glucanase – reduce viscosity
during mashing, improve
filterability
what is the Diastatic power?
the enzymatic activity of malted grains in converting starches into fermentable sugars during the mashing process. It indicates the ability of malt to produce enzymes, such as alpha-amylase and beta-amylase, which are essential for starch conversion.
what is Caramellization and roasting is important for?
flavour and colour
* Reduces or eliminates enzymatic activity
what is Speciality malts?
a minor part of the total malt used
specialty malts are used in smaller quantities and primarily contribute to the color, flavor, aroma, and mouthfeel of the finished beer.
what are Adjuncts
Unlike specialty malts, which are primarily used for flavor and color, adjuncts are primarily used to increase fermentable sugars and influence the beer’s overall composition.
- they are Non-malted ingredients
- Cereals: maize (corn), rice etc. – as source of sugar
- Diastatic power in the total formulation becomes crucial –
addition of enzymes (β-amylase) - Sugar
- Roasted barley (flavour and colour)
what role does water play as an ingredient in beer?
- Solvent and main ingredient
- Provides minerals for the yeast
- pH and minerals will affect enzyme activity and beer
flavour - Typical pH 5.2-5.5
- Hardness can influence flavour and enzyme activity
- Contaminants can cause off-flavours
Malt crushing
- Faciliatate mashing
- Husks should be intact – facilitate extraction and draining (sparging, lautering)
- Particle size after crushing is crucial.
what is mashing?
degradation of starch
what are themost common type of mashing?
Most common: Infusion mashing
* Crushed malt is mixed with warm water
* Different temperature rests leads to optimal enzymatic
activity
* Which rests are used depend on the beer
* In some malts protein and β-glucan are already
considerably degraded (“highly converted” malts)
what happens at Low T (63-65 °C) during mashing?
efficient degradation to maltose, smaller body (lager)
what happens at High T (>65 °C) during mashing?
less efficient degradation, larger body (ale och stout)
what is the optimal ph for mashing
Optimal pH=5,2-5,5
–>adjustement of water pH with acid or acidulated malt
what is the Typical saccharification rest
60-90 min
what happens at Too high T (approx. >80 °C) and/or too long time during mashing?
extraction of polyphenols
what is Mash-out?
short time >74 °C to deactivate enzymes and
decrease mash viscosity
what step is after mashing?
Draining and sparging
what is sweet wort
Sweet wort is the liquid extracted from the mashing process during beer brewing. It is rich in fermentable sugars and other soluble compounds derived from malted grains
The mash is drained and sparged with water (70-77 °C)
–> sweet wort
when does sparging stop?
when sufficent volume and/or the desired concentration of sugars has been obtained
how is Wort strength measured
°Oechsle, °Plato (refractive
index) or ”gravity” (relative density)
what functions does the boiling in beer brewing have?
Several functions
* Pasteurization
* Evaporation on unwanted aromas (e.g. dimethyl
sulphide)
* Precipitation of proteins –clarification
* Maillard reactions – colour
* Extraction of bitterness and flavour from hops!
* Clarification aids are often used – carrageenan
etc (forms complexes with proteins)
what is hops?
Hop is a vine with cones containing aroma and
flavour substances
* α- and β-acids (humulones och lupulones)
* Oils (hop flavour and aroma)
* Sensitive to oxidation
* Relatively expensive ingredient
what happens with α-acids During the boil?
α-acids are isomerized–> bitterness
what is involved in foam stability?
α-acids are involved in foam stabilty
how is the hops affected during the boil?
- The extent of isomerization depends on boiling time
- Long boiling evaporates aroma substances
- Added at different times during the boil
- Isomerized hop extracts
what step is after the boil?
Fermentation and conditioning
what happens during Fermentation and conditioning?
- Rapid cooling after boil
- Oxygenation of wort
- Addition of yeast
- Conditioning (and sometimes secondary fermentation)
- (Filtration)
- (Pasteurization)
what are Different types of yeast in beer?
- Saccharomyces cerevisiae
–>Ale - Saccharomyces pastorianus (syn. carlsbergensis och uvarum) –>Lager
- Brettanomyces –> ”wild yeast”, can ruin beer but desirable on some types of beer.
- Some beers –> lactic acid bacteria
what does the temp influence during fermentation?
Temperature has a strong influence on which
flavours are generated
What does higher temp during fermentation produce?
High T (>18 °C) gives higher production of esters,
ethanol, higher alcohols (fusel alcohols), acetic
aldehyde etc. (Typical for Ale, Stout etc.)
What does low temp during fermentation produce?
Low T (<12 °C) lower production of flavour compunds
”cleaner taste” (Lager)
what happens when sugar is depleted during fermentation?
the yeast can metabolize other compounds which affects the taste
Some common flavours generated by yeast
Acetic aldehyde -Green apple
Fusel alcohols-Solvents, spirits
Oraganic acids (acetic, malic, citric etc)- Sour
Esters- Banana, raspberry, pear etc.
Hydrogen sulphide-Rotten egg
2,3-butandione (diacetyl)-Butter scotch
Glycerol- Sweet
what are Some quality aspects of beer?
Microbial contamination
* Staling – oxidation
* Main limiting factor for beer shelf-life
* Foaming and foam stablity
* Gushing
* Related to microbial contamination in the malt
* Foam stabilizing compunds
* Oxalates (beer stone) – nucleii for CO 2
- Lacing
- Colloidal stability – chill haze formation
- Proteins and polyphenols and more
- Eliminated by filtration
