Res School test Flashcards
(12 cards)
Why are higher amounts of calcium bentonite required for stabilisation compared to sodium bentonite?
Calcium hinders the infusion of water between the alumina-silica plated of bentonite during slurry preparation, which consequently leads to less efficient interaction of the alumina-silica plated with the wine protein.
Due to the 2+ charge of calcium, sodium is 1+.
What fining agent is soluble at pH 7-10 but insoluble at pH 3-4?
Casein, Therefore it does not contribute to residual protein in the wine.
What is the conversion factor from copper sulphate pentahydrate to Cu(II)
0.254
Why does isinglass have a fibrous structure?
High proline content in its proteins inhibits hydrogen bonding within the protein hence the fibrous structure.
What cation replaces Al3+ in bentonite to give a negative charge character to alumino silicate plates?
Mg2+
In what soil type is bentonite usually found?
volcanic
During red wine fining with isinglass, whereby the protein interacts with phenolic compounds, which order do the different types of intermolecular bonds take place?
- hydrophobic bonding
- hydrogen bonding
- aggregation/precipitation.
Which chemical group do proteinaceous fining agents and PVPP have in common?
carbonyl group
What could be used to measure the breakthrough capacity of an anion exchange column used to remove acetic acid from wine in a reverse osmosis system?
pH
How does ethanol impact the precipitation of potassium hydrogen tartarate?
It hinders the ability of water to separate K+ ions into coming into contact with HT- ions by disrupting the hydrogen bonding structure of water.
Which form of the precipitated crystal is responsible for the blue colour of blue fining lees?
KFe(III)[Fe(II)(CN)6]
What is the relative abundances of the sulphur species (HS-, S2-, H2S) at typical wine pH. The pka1 and pka2 are 7 and 13 respectively.
H2S>HS->S2-
