Pericarp and testa Flashcards
(22 cards)
What are the two layers that form underneath the husk?
Pericarp and testa
What is the outermost layer of the pericarp?
Cuticle
What does the pericarp consist of?
Outer pericarp and inner pericarp
What are the two layers of the outer pericarp?
Epidermis and hypodermis
During grain development, what happens to the epidermis?
It becomes compressed and cells become less specialised
How thick is the pericarp layer?
~ 0.5mm
What percentage of total grain weight does the pericarp account for?
1%
What is the permeability characteristic of the pericarp?
Semipermeable to water
What percentage of the grain’s weight does the testa make up?
1-3%
What is the composition of the testa?
Two layers of waxy cuticles
What does the testa protect?
The embryo
What substances can the testa selectively allow to permeate?
Gibberellic acid
What is the micropylar region of the grain known for?
More porous, helps allow water uptake during steeping
What compounds are rich in the testa?
Polyphenolic and phenolic materials
What are the major simple phenolic compounds from malt?
Ferulic acid and p-coumaric acid
What group do ferulic acid and p-coumaric acid belong to?
Hydroxycinnamic acids (HCA)
What aroma does 4-vinylguaiacol (4-VG) give to beer?
Spicy, or clove-like aroma
Is 4-VG considered an off-flavour in most beers?
True
In which type of beer is 4-VG usually desirable?
German wheat beers
What is the main barrier to water entry in the grain?
Testa
Fill in the blank: The testa makes up ______ of the grain’s weight.
1-3%
True or False: The testa is thought to be a significant source of wort or beer polyphenols.
False
