Element three - Maturation, Treatments and Bottling, Part 3 Filtration,

Question 1

The effectiveness of a filter is determined by?

Answer 1

the volume of wine which is filtered per cycle, until the filtering surface becomes blocked.

Question 2

Bacteria clog more than yeasts as they tend to agglomerate in groups, so wines that has had ________ are more difficult to filter,

Answer 2

malolactic fermentation.

Question 3

Filtering surfaces are defined according to their rating: (2)

Answer 3

1. according to their average pore size

2. to their maximum pore size

Question 4

Depth filtration uses a thick layer of finely divided material such as?

Answer 4

Diatomaceous earth or pads made of cellulose fibers.

Question 5

Earth filtration take place in two stages:

Answer 5

1. pre-coating: a layer of coarse grade earth is deposited on a supporting surface.
2. filtration: earth is now mixed into wine, and passed through the pre-coating supporting surface.

Question 6

Diatomaceous earth or Kieselguhr is what and comes fro where?

Answer 6

sedimentary rock of skeletons of diatoms, algae. found in Santa Barbara California.

Question 7

What would be an option to Diatomaceous earth?

Answer 7

Perlite, a part of a volcanic rock, a similar function.

Question 8

Sheet or pad filtration work how?

Answer 8

A flow through layers of stainless steel plates, with a sheet or pad on top of it, through the filter and the the same over and over.

Question 9

Filter and pads are usually made from :

Answer 9

Celluloses, prepared from pine tree, chemically purified and broken down to different grades.

Question 10

What are the advantage and the disadvantage with depth filtration? (2)

Answer 10

Advantage: 1. can cope with a high content of solids, filtred reasonably easily. 2. Filter system is simpel to operate and inexpensive.
Disadvantage: 1. need to prevent particles from going to the clean side.
2. the filtration is not absolut.

Question 11

Surface filtration works how?

Answer 11

uniformly-sized pores, pores ar big enough to block lager unwanted particles (yeast and bacteria).

Question 12

What size of a surface filter will remove all yeast and bacteria?

Answer 12

0.45 micron

Question 13

Membrane filters are made from and how does it work?

Answer 13

thin, flexible plastic or ceramic material in a range of pore size.
two or more membrane of different pore size, remove different stuff of different size. Washed and reused!

Question 14

What are the advantage and the disadvantage of Cross-flow membrane filtration?

Answer 14

Advantage: this is the super filtration technique so even the dirtiest of wine can be filtrated.
Disadvantage: machine is expensive.

Question 15

What are the advantage (1) and the disadvantage (3) of surface filtration?

Answer 15

Advantage: 1. the process is absolute, guaranteeing that everything bigger than the pore size will be removed. ‘
Disadvantage:
1. the flow rate slow down as the volume of wine passing through.
2. membrane can be clogged easily.
3. filters are expensive.

Question 16

Ultra filtration is strictly controlled by the Eu, how does it work?

Answer 16

using a membran that can filter specific components, as tannin, sugar and acid… etc..

Question 17

Reverse osmosis (RO) work how and is used for?

Answer 17

highly selective membran that only allow small molecules to pass, high pressure is added.
Used for removal of water, de-alcoholise a finish wine or a part of it. (the alcohol can be put back in the same wine but to a max of reduction by 2%), Decreasing the levels of acetic acidity.

Question 18

Osmotic distillation is used for what typ of wine?

Answer 18

High quality grape juice concentrates. Juice used for sweeten grape must prior to fermentation, increase of final alcohol.

Question 19

how does the osmotic destillation work?

Answer 19

High pressure cause the water to pass though a PTFE or teflon membrane leaving the rest behind, the grape juice is now concentrated.