Winery Considerations

Question 1

What is cryoextraction?

Answer 1

Freezing harvested grape and pressing to separate solids and frozen water; grape must may also be freezed

Question 2

What are measures of grape sugar concentration?

Answer 2

Baume (relative density of fermenting must)
Brix/ Balling (hydrometer measurement used in sugar industry; popular in new World)
Oechsle (hydrometer scale used in Germany, Switzerland)

Question 3

What substance is formed if ascorbic acid is added to a wine that does not have adequate levels of SO2?

Answer 3

Hydrogen peroxide

Question 4

What does acetic acid bacteria do?

Answer 4

Converts alcohol into acetic acid (vinegar); acetic acid + alcohol = ethyl ethanoate (acetone)

Question 5

After how long is it considered that new barrels no longer impart much flavour on the wine?

Answer 5

3-4 years

Question 6

What is the advantage of using pectolytic enzymes in wine making?

Answer 6

They help extract more clear juice from the grape flesh

Question 7

What are types of presses?

Answer 7

Vertical screw press (basket press)
Horizontal screw press (Vaslin)
Pneumatic press (Willmes)
Tank press
Continuous screw press

Question 8

What can cause a wine to smell of geraniums?

Answer 8

Lactic acid bacteria metabolising sorbic acid in wine

Question 9

What is the most likely cause of a wine having a very unpleasant smell similar to bad eggs or drains?

Answer 9

Using highly anaerobic wine making techniques: Reduction causes formation of hydrogen sulfide which smells of rotten eggs
Hydrogen sulfide may be removed by aerating or adding small quantities of copper sulfate

Question 10

Diacetyl is a by-product of wines that have undergone MLF, how does this impact on the wine?

Answer 10

It adds a buttery richness to the wine

Question 11

Why are nitrogen levels important in grape fermentations?

Answer 11

1. When there is a lack of nitrogen hydrogen sulphide (H2S) can be produced
2. If it is lacking it can contribute to a stuck or sluggish fermentation–kick-start by adding nitrogen-rich products (DAP or vit B)

Question 12

What are by-products of fermentation?

Answer 12

Glycerol (glycerine), acetaldehyde, ethyl acetate, aromas esters, fusel oils

Question 13

What is and how does isoamyl isotate form?

Answer 13

Fermentation at low temperature causes retention of isoamyl acetate (banana/ pear drop)

Question 14

What is considered an average extraction rate, as a percentage of total weight, for still wine?

Answer 14

70%

Question 15

What types of wines is destemming not appropriate for?

Answer 15

Sparking and red wines that undergo carbonic maceration

Question 16

What are clarification methods?

Answer 16

Sedimentation and racking
Fining
Filtration
Centrifugation
Floatation

Question 17

What are clarification methods for whites?

Answer 17

Cold settling (sedimentation and racking: 5-10 degrees; can use stainless steel and rack every two months to remove lees and prevent reduction)
Centrifugation
Diatomaceous earth filtration (good for aromatic varieties)
Flotation

Question 18

What are the general conditions for skin contact in aromatic white wine production?

Answer 18

Temperature between 5 -10°C up to 24 hours

Question 19

When can hydrogen sulphide develop?

Answer 19

Stuck fermentation: Hydrogen sulphide formation: No nitrogen > yeast breaks down amino acids > hydrogen sulfide releases > smells like rotting eggs
Unstired lees: Unstirred > hydrogen sulphide, mercaptan odours (cabbage-like)
Bottle maturation: Extended storage > reduction (hydrogen sulphide aroma—rotten eggs)

Question 20

What are must enrichment techniques?

Answer 20

Chaptilization (add sucrose)
Add RCGM
Vacuum evaporation
Reverse osmosis
Cryoextraction

Question 21

Which of the following can eliminate hydrogen sulphide in wine?

Answer 21

Lees stirring
Racking
Passing through a copper pipe
Add copper sulphate

Question 22

What is the impact of hyperoxidation on aromatic varieties?

Answer 22

Effect sometimes favourable or neutral for Alsatian and German varieties, Chardonnay, Chasselas, Garganega and Trebbiano
Considered detrimental for SB

Question 23

What are cap management methods?

Answer 23

Pumping-over (remontage)
Punching down (pigeage)
Rack and return (delestage)
Submerged cap 
Rotovinification
Autovinification (extended version of pumping over)

Question 24

What is thermovinification?

Answer 24

heating grape must to 60-80 degrees Celsius for 20-30 minutes then cooling to fermentation temperature; encourages maximum colour extraction; time-saver

Question 25

What is flash expansion (flash detente)?

Answer 25

Fermentation technique: Place pre-heated grapes (65-90 degrees Celsius) in intense vacuum > grapes cool to 30-35 degrees > cells desrupted, rapid release of anthocyanins, tannins

Question 26

Why would a vineyard manager use “plastic mulching” in a newly-planted site?

Answer 26

To reduce the risk of water stress damaging the young vines.

To encourage microbiological activity in the soil.

Question 27

Which one of the following produces a buttery smell in wine that has undergone malolactic fermentation?

Answer 27

Diacetyl

Question 28

Pre-fermentation cold soaking, requires which of the following?

Answer 28

Higher levels of SO2 to prevent spontaneous fermentation taking place

Question 29

What does pH influence in wine?

Answer 29

Colour, taste, quantities of molecular sulfur dioxide > overall stability

Question 30

What are types of oak used to make barrels?

Answer 30

Quercus alba: American; low phenols; high aromatics (oak lactone (coconut))
Quercus petraea: less extractable tannin; high aromatic potential (lactone, volatile phenols like eugenol (clove), phenol aldehyde like vanillin)
Quercus robur: low odoriferous compounds; high extractable polyphenol content