Wine Components & Winemaking

Question 1

What is the predominant alcohol in wine?

Answer 1

Ethanol

Question 2

What are the main types of acid in grapes?

Answer 2

Tartaric and Malic

Question 3

What is the typical total acidity in wine?

Answer 3

5.5-8.5g/L

Question 4

What is pH?

Answer 4

A scale of measurement for the concentration of the effective acidity of a solution

Question 5

What is the typical pH range of a wine?

Answer 5

3 to 4

Question 6

How does the pH scale work?

Answer 6

It is an inverse scale so the lower the number, the more concentrated the acidity.
The scale is logarithmic so a pH of 3 is 10 times more acidic than a pH of 4

Question 7

How does a low pH affect a wine?

Answer 7

A low pH increases the microbiological stability of a wine
Increases the effectiveness of SO2
Gives red wines bright red colour
Enhances wine’s ability to age well

Question 8

What are the 4 sources of aromatic compounds in wine?

Answer 8

Aromas from the grapes
Aromas created by fermentation from precursors
Aromas originating from fermentation and it’s by-products
Aromas from other sources

Question 9

What are 2 examples of aromas that come from the grape?

Answer 9

Methoxypyrazines and Rotundone

Question 10

What are 2 examples of aromas that are created by fermentation from precursors?

Answer 10

Thiols and Terpenes

Question 11

What are 3 examples of aromas originating from fermentation and it’s by-products?

Answer 11

Esters
Acetaldehyde
Diacetyl

Question 12

What are Esters?

Answer 12

Compounds which has formed by the reaction of certain acids and alcohols.
Majority are created through the actions of yeasts in the fermentation process.
They are responsible for many fresh and fruity aromas, the most common ester is Oamyl Acetate which gives banana aromas

Question 13

What is Acetaldehyde?

Answer 13

It is an aroma that occurs in wine due to the oxidation of ethanol.
It masks fresh fruit aromas and has a stale smell regarded as a fault in most wines
It is an important component in the smell of Fino Sherry

Question 14

What is Diacetyl?

Answer 14

It is an aroma that is produced during fermentation and especially during Malolactic Conversion
It contributes a buttery aroma

Question 15

What is Eucalyptol?

Answer 15

It is an aroma volatized from Eucalyptus trees by heat and absorbed into the waxy layer of the skins of grapes in nearby vines

Question 16

What is the allowed residual sugar in a Dry/Sec/Trocken wine?

Answer 16

Up to 4g/L or not exceeding 9g/L provided that total acidity is not more than 2g lower than RS content

Question 17

What is the allowed residual sugar in a Medium Dry/Demi Sec/Halbtrocken wine?

Answer 17

More than 4g/L and not more than 12g/L or up to 18g/L provided that total acidity is not more than 10g below the RS content

Question 18

What is the allowed residual sugar in a Medium/Medium Sweet/Moelleux/Lieblich wine?

Answer 18

More than 12g/L and not exceeding 45g/L

Question 19

What is the allowed residual sugar in a Sweet/Doux/Suss wine?

Answer 19

At least 45g/L

Question 20

Why is oxygen threatening for the production of fresh fruity wines?

Answer 20

Oxygen breaks down the aroma compounds that gives these wines their style

Question 21

What is the name of the practice of minimising oxygen exposure during winemaking?

Answer 21

Reductive or protective winemaking

Question 22

What are some ways of limiting the effect of oxygen on the must or wine?

Answer 22

Avoiding ullage in vessels
Use of inert gases
Addition of SO2
Use of impermeable containers
Cool, constant temperatures

Question 23

What are some techniques of increasing oxygen exposure?

Answer 23

Use of cap management techniques in red wine fermentation that spray or splash the must or wine
Use of small wooden barrels
Increasing the number of rackings or lees stirring
Allowing ullage in containers without use of inert gases in headspace
Use of techniques that involve pumping oxygen through the must/wine

Question 24

What is hyperoxidation?

Answer 24

A technique that involves pumping oxygen through the must

Question 25

What is micro-oxygenation?

Answer 25

A technique that involves pumping oxygen through wine

Question 26

What are the two main uses for Sulfur Dioxide?

Answer 26

Anti-Oxidant Anti-Microbial

Question 27

How does Sulfur Dioxide work as an antioxidant?

Answer 27

It redues the effects of oxidation by reacting with the products of oxidation reactions, so they cannot oxidise further compounds in the wine

Question 28

How does Sulfur Dioxide work as an antimicrobial?

Answer 28

It inhibits the development of microbes such as yeast and bacteria

Question 29

What are the various forms of SO2?

Answer 29

Gas, liquid or solid Sulfur dioxide, potassium metabisulfite or potassium bisulfite

Question 30

What is the maximum level of SO2 allowed in white and reds wines in the EU?

Answer 30

White wine - 200mg/L Red wine - 150mg/L

Question 31

What is bound SO2?

Answer 31

When SO2 is added to must or wine it dissolves and some of it reacts with compounds in the liquid - this portion is called bound SO2

Question 32

What is free SO2?

Answer 32

The proportion of SO2 that is not bound is called free SO2, the vast majority of the free SO2 exists in a relatively inactive form and a small portion exists as molecular SO2

Question 33

How does a lower pH affect the efficacy of SO2 in a wine?

Answer 33

At lower pH levels a greater proportion of free SO2 is in the molecular form, making it more effective against oxidation and microbes

Question 34

What are some common forms of enrichment?

Answer 34

Adding dry sugar Adding grape must Adding grape concentrate Adding RCGM

Question 35

What are some common processes of concentration?

Answer 35

Reverse osmosis Vacuum extacting Chilling

Question 36

Why would sugar be added when fermentation is already underway?

Answer 36

Because the yeasts are already active so they can cope better with the additional sugar in the must

Question 37

What acid is typically used for acidification?

Answer 37

Tartaric acid

Question 38

Why would acidification typically be done before fermentation?

Answer 38

So that the fermentation can benefit from a lower pH and it is believed to integrate better at this stage

Question 39

How is deacidification carried out?

Answer 39

Calcium carbonate (chalk) or potassium carbonate is added to the wine and it lowers the acidity by the formation and precipitation of tartrates

Question 40

What temperature should a ferment be for a fresh fruity white wine or rose?

Answer 40

Cool - 12-16°C

Question 41

What temperature should a ferment be for a easy drinking fruity red wine or a less fruity white wine?

Answer 41

Mid - 17-25°C Middle of the range for less fruity white wines, top of the range for barrel fermented white wines

Question 42

What temperature should a ferment be for a red wine with pronounced flavour concentration?

Answer 42

Warm - 26-32°C

Question 43

At what temperature might a fermentation get stuck?

Answer 43

Above 35°C

Question 44

Why are concrete vats coming back into fashion as a fermentation vessel?

Answer 44

They have a high thermal inertia

Question 45

What is Malolactic Conversion?

Answer 45

The result of lactic acid bacteria converting malic acid into lactic acid and CO2, it also produces heat

Question 46

Which conditions encourage Malolactic Conversion?

Answer 46

Temperatures of 18-22°C Moderate pH (3.3-3.5) Low total SO2

Question 47

What conditions inhibit or prevent Malolactic Conversion?

Answer 47

Temperatures below 15°C Low pH Moderate levels of SO2

Question 48

What are the 4 main outcomes of Malolactic Conversion?

Answer 48

Reduction in acidity and rise in pH Some colour loss in red wines Greater microbial stability Modification of the flavour

Question 49

What might an advantage of carrying out Malolactic Conversion in a barrel vs. a tank?

Answer 49

The ability to stir the lees at the same time as it is happening, and promote better integration of the flavours