Unit 3 - Lesson 4 - Grapes Flashcards
Difference between molasses and grapes
Molasses can store in drums need to use grapes
For unaged brandy what type of grape?
Focus on aromatic grapes
What is the difference between storing molasses and grapes?
Molasses can be stored in drums for months
Grapes only two weeks
What is the Crush pad
Name give to winery’s grape processing operations
Hand harvest versus mechanize
Hand is expensive but selective
Higher upfront costs, less discriminant
Why remove stems? Why not remove stems?
Stems - have tannins that are not attractive
However, stems contribute to mouthfeel and some flavors
Where does destemming typically take place?
On the sorting table (some are mechanized)
Describe machine destemmers
Use rubber rollers made of nylon or rubber
Rolles just enough to break the skin without pulverizing
What determines choice of destemmer?
The distillers requirement for throughput
Large requirement means mechanized
3 types of grape press
Basket or ratchet press
Bladder press
Continuous Screw Press
Describe Basket Press
Baskets on top of metal plate Screw down the middle with a top plate Grapes load and top is "ratched" down the screw pressing the grapes Holes in the basket let juice drip Very simple NO ELECTRICITY
Challenge for Basket/Ratchet Press
Too much pressing breaks seeds and cause “green flavors”
Describe Bladder Press
Common for Brandy
A large perforated cylinder with inflatable membrane down the middle
Bladder expands from middle, pressing grapes against the cylinder and juice is collected
Why are Bladder presses popular?
- Easy to operate - little physical labor
- Programmable - eg to the correct pressure
- Gentler on grapes without sacrificing juice yield
Describe a Continuous Screw Press
Horizontal and perforated
Grapes feed while screw is moving pushing them forward increasing pressure on them as they go
Pushes pomace to the end which is ejected
Fed a continuous stream of grapes
1st run grape juice
Free run - requires little pressure
Why dont Brandy makers separate press fractions of wine (eg Free Run vs Pressed)?
Tannins are not a concern since they are not volatile
Drawbacks for a Bladder Press
Expensive
Requires specialize hookups
Large
What is a continuous screw press?
horizontal cylindrical chambers with perforations throughout
Large screw through middle
Feed continuous stream
Problem with screw press?
force on the fruit. Therefore, if the press operator is not paying attention, the machine can add green flavours and unwanted tannins to the juice.
Solid portion of grapes
amounts to 30-35% per volume ofgrapes. For instance, if we have 1000 L ofgrapes,we will have between 300-350 L of grape solids. Our press should thus be sized to handle 3.5 hL.
What do brand makers like
This initial juice fraction usually contains lower levels of tannins than the other fractions.
Brandy distillers do not generally separate press fractions like this; tannins are not much of a concern as they do not volatilise in the still very easily.
1 Ton of grapes yields
600-680 liters of juice
What is good about cumbling
Crumbling is when the press retracts the pressure on thegrapes. The press operator can break up the pressed skins by hand. Alternatively, the press rotates on its axis and breaks the grape skins up, and then shuffles them. When the press turns back on, more juice can be extracted more evenly.
