Human factors in the winery Flashcards
Roles of the oxygen2
Oxygen is a gas that can react with grape/juice during wine making and maturation
Roles of SO2 (solfure dioxide)
(i) It’s an antioxidant and antiseptic almost indispensable in the winery
(ii) restricted by law because it can be toxic
Types of winery vessels
(i) Oak
(ii) Steinless stell
(iii) Concrete vessels
Alcoholic fermentation definition
Conversion of sugar into alcohol and CO2 through the action of the yeast (+ flavour and temperature)
Explain Malolactic fermentation (MFL)
(i) it takes place one the alcoholic fermentation has finished
(ii) carried out by lactic acid bacteria that convert tart malic grape acid into lactic acids
(iii) MFL reduces the acidity and create buttery flavours
(iv) smooth the acidity
(v) Chardonnay
Types of adjustments
(i) Enrichments - sugar and alcohol
(ii) Acidification - addition of tartaric acid in powder
(iii) Deacidification - addition of alkali
What happens in case of wine maturated aerobically?
(i) in term of color: red wines become paler and white wines become deeper in colour
(ii) the amount of oxydation depends on size of the vessels and time
- -> 225l barrique have a greater oxidative effect than larger vessel, due to larger surface of wine exposed to wood (no more than 2 years)
- –> Oxidative effect enahanced by containers not completely full. This technique is used for fortified wines (ie. Oloroso, Sherry, Tawny Port and Rutherglen Muscat). This develop tertiary character as caramel, toffee and nuts
(iii) Over exposure can be damaging as wine lose its freshness and fruit flavour
(iv) Bacteria with oxygen can turn wine into vinegar
Effects of SO2
(i) Antioxidant - protects grape juice and wine from oxidation
(ii) Antiseptic - against bacteria that can cause unwanted flavours in the wine
What is the most common yeast?
Saccharomyces cerevisiae due to his tolerance to SO2 and alcohol
Thnings to know about alcholic fermentation
(i) It won’t start if the temperature is below 5°
(ii) it should continue naturally until all the sugar is consumed
(iii) it can stop before if the yeast run out of nutrients or the temperature is above 35°
Types of yeast
(i) ambient yeast strains - complex flavour but hard to control
(ii) cultured yeast - limited complexity of the wine but easy to control during wine making
Red wine fermentation temperature
20° - 32°
White wine fermentation temperature
12° - 22°
High volume inexpensive white wines (=’dry and fruity)
Pinot grigio, Chardonnay
High volume inexpensive red wines
Cabernet Sauvignon, Merlot, Syrah/Shiraz, Grenache/Garnacha
Which one of the following is used to protect wine from oxidation?
- Sulfur Dioxide
- Kieselguhr
- Acetic Acid
- Hot bottling
1.
Techniques of clarification
(i) Sedimentation
(ii) Fining
(iii) Filtration
Explain what carbonic maceration is and the style of wine it produces
x
List 4 methods of concentrating the grapes sugars in the production of sweet wines.
y
Describe the characteristics of the Riesling grape
z