6708975
Description
Flashcards by Martha Cima, updated more than 1 year ago
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Created by Martha Cima
over 7 years ago
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| Question | Answer |
| Common Factors Affecting Quality | - Raw Material - Processing of Raw Material - Alcoholic Fermentation - Post Distillation Operations |
| Ways carbohydrate is stored by raw materials | - Starch -Sugar - Inulin |
| Alcoholic Fermentation | Sugar + Yeast --> Acohol, Co2 + Congeners |
| How can the influence of yeast on style be controlled by producer? | Choice of yeast strains, commercial or isolated culture. Wild ferment using natural yeasts. Environmental Conditions effect yeast e,g amount of yeast nutrients so environmental conditions must be kept consistent to avoid variation. |
| Types of Alcohol found in Spirits | Ethanol = Most abundant (up to 99%) Methanol Fusel Oils (propanol, butanol, amyl alcohol) Measured ABV or Proof |
| How Distillation Works | Separation of fractions in alcoholic liquid through boiling and condensing . Works because the boiling point of Ethanol is lower than water (78.3°C v 100°C) also concentrates other Fractions containing volatile congeners |
| Types of congeners | - From raw material, yeast or from chemical reactions - Esters (fruity Aroma) - Acids - Aldehydes - Sulphur Compounds |
| Why is copper important in distillation process? | -Easy to shape when making stills and is a good conductor of heat - Removes sulphur compounds from final spirit - Copper always found in stills |
| Rectification | Process of progressive increase in level of alcohol due to reflux |
| Reflux | Vapours and liquids mix as vapours condense and fall back down as liquid. Heat is shared between liquid and vapour causing less volatile fractions in vapour to condense. |
| Rectification plates | - Found in Column stills and some Pot Stills - Increase interaction between the liquid and vapour increasing reflux. |
| Head Condenser | Enclosed section at top of still cooled with cold water. Encourages condensation. |
| What are the two principle types of condensers | Worm tub and shell tube. |
| How do condensers work | Have a tube/tubes where spirit enters as vapour and leaves as a liquid and a coolant (typically water). Coolant has to be continuously refreshed |
| How many rectification plates can there be in a column still | Between 15 and 42 |
| 5 elements shared by all pot stills | 1. heat source 2. Pot 3. Head (where reflux happens) 4. Lyne arm/connecting tube 5.Condenser |
| 3 methods that could be used to heat a pot still | 1. Direct Heating -metal structures dragged across base to stop scorching 2. Steam - though coil in pot or by a jacket 3. Water (Bain marie) |
| The effects of temperature gradient in pot stills | If large gradient there will be more reflux and less volatile congeners will be found in final spirit. Fast boil will have less gradient and more congeners. |
| How will a tall head on a pot still make a difference to the final spirit style.? | A tall head will allow a larger temperature gradient so more reflux and less congeners. Design of still can have defining influence on style. |
| Effects of angle of linking tube in pot still | If angled up reflux will continue |
| How can the design of a pot still help reflux to be increased? | -Rectification plates added -Tall head - linking tube angled up - gentle heating method |
| What is the purpose of the 1st distillation in double pot still distillation | To separate all of volatile fractions from some of water and all non volatile parts. Generally distilled to relatively low strength |
| Making a cut | 1st liquid (heads) to come off still is high in volatile fractions and can be tainted by residue in still head. Cut is made to heart when free of undesirable compounds. |
| What is found in the tails that can gives a richer and weightier character at lower levels but if too high will be unpalatable. Why are these found at higher concentrations in the tail. | Fusel oils. Temperature of alcoholic liquid in still rises in the process of distillation as alcohol becomes more dilute. Fusel oils and other less volatile fractions are distilled. (e.g peaty congeners have high boiling points) |
| Ways of promoting reflux in column stills | - Rectification plates -Head condensers - tube that preheats the alcohol before it enters still - Spirit may be poured in to promote downflow |
| 2 Stages of continuous distillation | 1. Analyser/Stripper - volatile fractions separated from most of the water and some of the non volatile parts 2. Rectifier Could be one enormous column with rectifier above analyser |
| Coffey Still | Patented by Aeneas Coffey in1830 Double column still Tube preheats liquid in rectifier Heads Heart & tails removed @ same time Temp gradient constant and rate of liquid constant |
| Techniques for further reduce flavour of spirit after column distillation (x2) | 1. Hydroselection - Removes Fusel Oils HRC reduced to 20%abv w/ hot water making fusel oils more volatile 2. De-methalising - Removes Methanol. Spirit is heated in reboiler and methanol is separated and removed from top of column. |
| Why is de-methalysing normally needed in vodka production? | EU legally required maximum level of methanol is very low. |
| Post distillation operations (x4) | Maturation Addition of Flavours Blending Finishing (legal requirements and choice of producer) |
| Three ways that an oak barrel can flavour a spirit | 1. Subtract harsh flavours from young spirit 2. Adds Flavour - Vanillin, lactones(coconut), eugenol (spice) 3. Oxygen |
| Variables in oak barrels that will effect style of final spirit | -Species of oak -Amount of Toast/Char - Barrel Age - Previous Contents - Fill Strength - Warehouse Temperature/Humidity |
| Species of oak used in aging spirits | -Quercus Alba -North America - Quercus Robur and Quercus Sessiliflora from Europe |
| At what abv are spirits usually distilled to before entering barrel so as not to extract unpleasant flavours | 60-70% |
| Blending | -Needs experience -After blending allowed to homogonise for a few months before finishing |
| Finishing | -Dilution - pure water, may be done in stages -Colouring - Caramel to make consistency -Filtering - chill filtration, charcoal filtration... |
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