Understanding Wine Technology : Chapter Four

Front 1

Describe our atmosphere in terms of composition of nitrogen and oxygen.

Back 1

Nitrogen is 4/5ths of our atmosphere and oxygen is 1/5th.

Front 2

Define anaerobic.

Back 2

Anaerobic describes a state without oxygen.

Front 3

Define aerobic.

Back 3

Aerobic describes a state requiring oxygen.

Front 4

What is the molecular makeup of acetic acid?

Back 4

CH3COOH

Front 5

What is the chemical equation that outlines the conversion of ethanol to acetic acid through oxidation?

Back 5

CH3CH2OH + O2 -> CH3COOH + H2O

Front 6

What is the molecular makeup of ethanol?

Back 6

CH3CH2OH

Front 7

Name a potential downfall of a wine being produced completely anaerobically.

Back 7

The wine can suffer reductive taint.

Front 8

Chemically, what has happened when one can sense reductive taint?`

Back 8

Sulphur Dioxide has been reduced to dirty-smelling Hydrogen Sulphide.

Front 9

To prevent oxidation, what are gathered grapes dusted with after picking?

Back 9

Potassium Metabisulphite.

Front 10

Describe what potassium metabisulphite is and explain how it is used to aid in winemaking.

Back 10

Potassium metabisulphite is a stable white powder that liberates sulphur dioxide when wet. Therefore, if dry grapes are dusted with potassium metabisulphite, when the grapes are crushed, or somehow break, SO2 is liberated to protect the juice from oxidation.

Front 11

Other than potassium metabisulphite, which contains SO2, what other antioxidant may be used in winemaking?

Back 11

Ascorbic acid...or Vitamin C.

Front 12

How do you ensure that the oxygen in the fermenting vessels and pipelines will not affect the wine?

Back 12

You must flush the tanks and pipelines with harmless gasses.

Front 13

What gasses are used to flush tanks and pipelines to ensure no oxidation of the juice in winemaking?

Back 13

Carbon dioxide and nitrogen.

Front 14

Why is copper and bronze equipment banned in modern wineries?

Back 14

The ions present in copper and bronze are capable of increasing the speed of oxidation.

Front 15

What is 'dry ice'?

Back 15

Frozen carbon dioxide.

Front 16

Why might one put blocks of dry ice in a small quantity of wine in the bottom of a vat?

Back 16

The carbon dioxide which melts will be heavier than air, and thus, will force air out of a release in the top of the vat.

Front 17

At what proportion of CO2 in the atmosphere can cause unconsciousness and death?

Back 17

Five percent.

Front 18

What is the correct level of dissolved CO2 in a wine so that it feels lively without being prickly or flat?

Back 18

The correct level is around 800mg/L.

Front 19

Contrast the densities of carbon dioxide and nitrogen using air as a benchmark.

Back 19

Carbon dioxide is heavier than air while nitrogen is approximately the same density as air.

Front 20

Cite a downside of using extensive amounts of nitrogen in the making and storage of wine.

Back 20

The wine may lose much of its dissolved carbon dioxide and the product will come out flat.

Front 21

If not using carbon dioxide or nitrogen as an agent of antioxidation, what other gaseous element is available to you, though slightly more expensively?

Back 21

Argon

Front 22

Describe the density of argon as compared to air, nitrogen, and carbon dioxide.

Back 22

Argon is about as dense as carbon dioxide, therefore, being more dense than both air and nitrogen.

Front 23

Slightly dissolved nitrogen will show itself how in a wine?

Back 23

Slightly dissolved nitrogen may cause a froth to appear on the surface of the wine.

Front 24

Wine is what % water?

Back 24

85%

Front 25

In terms of relative molecular weight, one atom of oxygen is capable of destroying how much sulphur dioxide?

Back 25

One atom of oxygen is capable of destroying four times its weight of sulphur dioxide.

Front 26

What is sparging?

Back 26

Sparging is the process of injecting fine bubbles of gas into a liquid in order to remove dissolved oxygen.

Front 27

What are two gasses effectively used in the process of sparging?

Back 27

Nitrogen and carbon dioxide.

Front 28

Why must the process of sparging be used only sparingly even though it carries with it the incredible capability of removing dissolved oxygen in the wine?

Back 28

Sparging will not only remove oxygen, it can also remove volatile compounds which flavour the wine.

Front 29

Why would it be desirable to saturate the must with oxygen?

Back 29

Oxygen will give the yeast a kick start and the yeast will begin reproducing quickly.

Front 30

What is hyperoxidation?

Back 30

Hyperoxidation is a technique that involves the deliberate oxidation of the must before fermentation in order to craft a finished wine that will be more stable towards oxygen.

Front 31

How is hyperoxidation carried out?

Back 31

Hyperoxidation is carried out by bubbling air through the must without the addition of protective agents such as SO2.

Front 32

'Reduction' is a chemical term meaning what?

Back 32

The opposite of oxidation.

Front 33

What is micro-oxygenation?

Back 33

Micro-oxygenation is the introduction of oxygen to the fully fermented wine.

Front 34

What is the difference between hyperoxidation and micro-oxygenation?

Back 34

Hyperoxidation will be carried out to the must prior to fermentation and micro-oxygenation will be applied to the fully fermented wine.

Front 35

What is the main goal of micro-oxygenation?

Back 35

The main goal of micro-oxygenation is to change to polyphenolic structure of the wine by integrating the tannins and creating a soft age-worthy wine.

Front 36

When is the first dose of oxygen added during the process of micro-oxygenation?

Back 36

The first dose of oxygen during micro-oxidation is added after the primary fermentation and before malolactic fermentation.

Front 37

How much oxygen is added during the first 1-3 months of micro-oxygenation?

Back 37

Probably between 10-60/mg/L/month.

Front 38

Describe the structuring phase of the micro-oxygenation process.

Back 38

The structuring phase takes place between the primary fermentation and malolactic fermentation. Oxygen is added to the wine at a rate between 10-60mg/L/month.

Front 39

When does the harmonisation phase of micro-oxygenation take place?

Back 39

The harmonisation phase of micro-oxygenation takes place after malolactic fermentation.

Front 40

What is the rate at which oxygen is added during the harmonisation phase of micro-oxygenation? Contrast this with the rate at which oxygen is added during the structuring phase.

Back 40

During the harmonisation phase, oxygen is added at between 0.1 and 10mg/L/month. Whereas during the structuring phase, oxygen is added between 10-60mg/L/month.