Beer, Wine, Cider and Vinegar Flashcards
Give a definition to beer and brewing
Beer: Is a solution of water, alcohol and carbon dioxide that is flavored by carbohydrates, proteins, minerals, and different aromatic compounds that it acquires from malt, hops, and yeast.
Brewing: Is the combined process of preparing beverages from the infusion of grains that have undergone sprouting, and subsequent fermentation of the sugary solution produced, by yeast – where a proportion of the carbohydrate is converted to ethanol and carbon dioxide
What is wort?
Wort (/ˈwɜːrt/) is the liquid extracted from the mashing process during the brewing of beer or whisky. Wort contains the sugars, the most important being maltose and maltotriose,[1] that will be fermented by the brewing yeast to produce alcohol.
What is gravity density of the wort? How it is expressed? How you can calculate alcohol content out of it?
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 be)
Gravity can be expressed in degrees Plato or Original Gravity (OG) (aka Starting Gravity SG)
Original Gravity is expressed as a ratio of density relative to pure water.
Example 1.040 wort is 1.040 times as dense as pure water
Although, a number of variables will affect the final alcohol content the general rule of thumb is that the significant digit is an estimation of the final alcohol content
Example 1.040 = 4.0% Alcohol By Volume (ABV)
What is Hydrometer?
What is refractometer?
What is terminal gravity?
How to calculate ABV
Gravity is normally calculated using either a hydrometer or a refractometer.
Hydrometer: A weighted glass tube with a scale on the inside which stops at the relative density of the liquid being measured
Refractometer: Measures the original gravity only, based on the refractive properties of sugar. Alcohol distorts the readings
Terminal Gravity is 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)
ABV = (OG - TG) * 131.25
How the color of the beer is measured?
How the bitterness is measured and on what does it depend?
Light/ dark measurements are acquired by measuring the beer in a spectrophotometer. Tristimulus (red/green/blue system) are used to assess colour.
Bitterness: Is the level of bitterness you taste when you drink beer. It is measured in bitterness units (BU) which relates to ppm isomerized alpha acid
What is attenuation? How it is measured? What is apparent attenuation? How it can be altered? What does low or high attenuation means
Attenuation is a way to measure how complete a fermentation process is.
Apparent Attenuation=(OG-TG)/OG
Attenuation can be altered by sugar type, mashing method, composition of the wort, or type of yeast.
High apparent attenuation signifies a dry beer,(because all the sugar has been converted to alcohol) while low apparent attenuation signify a sweet beer
What is malting? Why?
Malting: Is the process of allowing the grain to germinate (usually by soaking them in water)
In theory you could produce beer from barley, wheat, or oats (the ancient brewers did), but it quickly became apparent that barley was the easiest to work with in this process.
- The aim of malting is to transform the food reserves in the grain into substrates that are convenient for fermenting in the brewery
- It is a controlled germination process that is not the same as natural sprouting of the seeds in the filed would be (all of the energy would go into seedling growth)
Need to stop malting before rooting, so the energy is not wasted there
How malting is done in detail done?
- The moisture content of the grains at the start and during storage should be no higher than 20%
- To commence the malting the grains are soaked in water to start germination (happens when the grains are at 42-46% moisture)
- The water is not left on the grains there are intermittent periods of drainage when air is blown though
- CO2 is dispersed and this promotes germination
- Air is blown through the germinating grain bed, and grains are turned slowing in drums or by automated turning arms
CO2 promotes germination
What is milling? Why it is done? What are the two types of mil? What is done after it?
- Milling is a process that breaks down the malt into smaller more fermentable sizes, also breaks own particles in a particular size helps to control the run-off speed at subsequent steps
- There are two types of mill:
Wet milling
Dry milling
•After milling the malt grist is classified via a sieve analysis
What is mashing? How it is done? What do you get in the end?
- Mashing is the process where ground malt is mixed with brewing water, such that a fermentable extract is produced that will support the growth of yeast
- The temperature of the brewing water is important, and the ideal temperature will depend on the type of beer being made. Temperature is important from batch to batch, to result in the same taste and alcohol content (make different amount of sugar to dissolve)
- The composition of the water is also important for different beer styles
- It generally takes about 3 hours
- After mashing wort is produced
Where hops originated? What are the types of hops? Why they are used? when they are added
- Hops was first cultivated in Bavaria (or possibly Scandinavia)
- Hops can be used fresh, dried, in pellets, or in the form of extracts
- Hops come in three varieties according to their function in the brew house
a) Aroma Hops (smell)
b) Alpha Hops (flavour)
c) Dual Purpose Hops (both)
- Wort is boiled with hops for a bit over an hour before being cooled down and yeast is added
- Hops add a bitterness to the beer, but can also add a floral taste or fruity or citrusy flavours or aromas
What is the approximate composition of beer? What are top 6 sugars present there
What is fusel alcohol? Why they are relevant to beer?
- yeast stress can lead to undesirable fusel alcohol production
- Fusel alcohols refer to alcohols that contain more than two carbons. Ethanol is a two carbon atom molecule.
Fusel alcohols cause hangover
What is the principal microorganism responsible for brewing? When it is added? at what conditions? what is the lag time?
- Saccharomyces cerevisiae is the yeast of choice, and there are specific brewers yeast that are used in beer making
- Sc is added to the wort in a very specific amount, adding too little leads to very slow initial fermentations, adding to much leads to competition between yeast and poorer growth
- Temperature is also important. If the wort is more than 5C cooler than the yeast ‘cold-shock’ will result and this will result in a prolonged lag period
- A normal lag phase is 6-15 hours
- For industrial fermentations, it is important that the microbe starts growing as quickly as possible, so that other microorganisms are discouraged
At what air conditions yeast can grow? What conditions are needed during beer making? Does the reaction is endless? What are the limitations
- Yeast can grow aerobically or anaerobically
- Anaerobic conditions are essential for the production of alcohol by yeast, sugar up-take is diminished in the presence of oxygen
- Theoretically, then fermentation should proceed for as long as anaerobic conditions are available and there are hexoses in the media, this does not happen in practice
- Budding requires cell wall synthesis which cannot happen in anaerobic conditions, therefore eventually growth must cease
- Eventually the level of ethanol present becomes toxic to yeast
- When fermentation slows the yeast cells flocculate and sediment out (which causes growth to slow even further)
Draw an approximate chart of how sugars are utilized by yeast during beer fermentation, what are four stages of growth? What max temperature during brewing? can you avoid fusel alcohols?
Fusel alcohol will be produced any ways, but want to minimize it
You do not want to go higher than 20C
- The lag phase is followed by a short phase of exponential growth
- During the exponential growth phase the yeast density can increase by four- to six-fold
- During exponential growth yeast are at their highest level of utilizing sugars and producing ethanol and carbon dioxide
- Exponential growth lasts for 48-60 hours, after which growth is decelerated before the cells reach stationary phase
Why do we need to control the temperature of brewing? What molecules impart fruity flavor in the beer and how it is produced
- A considerable amount of heat is also produced, and cooling is usually needed to keep the temperature down to 20-22C
- If the temperature gets too high higher (fusel) alcohols (propanol, iso-amyl alcohol, or iso-butyl alcohol) will be produced, and this will impart off-flavours
- Esters cause a fruity flavor, and produced during fermentation. They can create a taste and aroma like pears, roses, bananas or other light fruits. In very high concentration esters can create a solvent-like flavor. Esters are formed in beer by the “esterification” of ethanol.
What is happening when the final gravity is reached? How it is called?
- Once a beer has been fermented down to its final gravity, it is chilled to 9-11C
- Immediately after the fermentation beer is called ‘green beer’ and must still be conditioned before packaging
What are five considerations during conditioning?
- 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 10^7 cells per mL(will block any filter). 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 tanks.
- Minimize Oxygen: Oxygen is low in green beer. If O2 finds its way back in, antioxidants are added
Are pathogens an issue in brewing? then what should we be aware of? how to contain it?
- Pathogens are not an issue with brewing. Any pathogen are not resistant to even 4-10% ALCOHOL
- Both wort and beer are prone to spoilage organisms (particularly wort since it provides a nutrient rich, oxygenated environment)
- Process control is the best way to prevent contamination (mash should pass straight into copper for boiling, which sterilizes it)
- Beer isn’t a good growth media for bacteria because it has a low pH, a good ethanol concentration, and is largely devoid of nutrients
- Certain spores can survive the whole process and make it into canned beer, but they will likely not germinate
Who are included in potential anaerobic beer spoilers?
Aerobic?
Aerobic: LAB (Pediococcus and Lactobacillus), Zymomonas,Megasphaera, Pectinatus
Aerobic:AAB (Acetobacter and Gluconobacter)
How LAb, zymomonas, megasphaera and pectinatus can spoil beer
Anaerobic Beer Spoilers can include LAB (Pediococcus and Lactobacillus) which cause turbidity, acid notes, and unwanted flavours
Zymomonas: Infects cask-conditioned beers resulting in ‘cider sickness’ where there is a secondary fermentation with much frothing, a loss of sweetness, and off-odours due to hydrogen sulfide and acetaldehyde production. Due to failure in the cask-washing regime.
Megasphaera: Produces hydrogen sulfide in beer producing “rotten egg” smell. Cannot tolerate more than 2.8% ABV so only affects low alcohol beers.
Pectinatus rapidly converts finished beer into propionic acid, acetic acid, succinic acid, lactic acid, and hydrogen sulfide giving the beer a “rotten egg” smell
How aerobic beer spoilers can harm beer
Aerobic Beer Spoilers are primarily AAB (Acetobacter and Gluconobacter) they will result in the oxidization of ethanol to acetic acid. There will be a “raft” of surface growth in the beer that will lead to generalize turbidity, and the infected beer may have a “ropiness” quality
What is wine? Other names of wine alterations? How the climate is responsible for wine quality and what are vintages vs regular wine
- Wine is an alcoholic beverage made from grapes fermented without the addition of sugars, acids, enzymes, water, or other nutrients (Grapes is the only fruit that has enough sugars for fermentation without addition of sugar)
- Different varieties of grapes and strains of yeast will produce different styles of wines
- Variation is a result of complex interactions
- Wines not made from grapes can include sake (rice wine), mead (honey), or fruit wines (plum, cherry, elderberry, strawberry)
- Cane sugar must be added to most fruit wines
- Climate has a huge impact on the quality of the wine, and the same vineyard can produce very different wines from year to year
- Superior wines are known as vintages and cannot be blended with other wines
- Otherwise non-vintage wines are generally blended so that wine-makers can still have an acceptable product even in bad years
