Prac Book Flashcards
what do you measure to ascertain grape maturity?
- the concentration of TSS - total soluble sugars
- the concentration of T.A - total titratable acids
- ph
what is saccharomyces?
wine yeasts… a genus of fungi
what are the primary sugars that create the “food” for the yeasts to feed on?
fructose and glucose
what are the two main acids in grapes?
malic and tartaric
what two methods/apparatus are used to determine the concentration of total soluble sugars?
hydrometer and refractometer
what does it mean if the wine is fermented dry?
fermented to the point where no more sugars are available
why is baume useful?
it is a good guide to the alcohol (ethanol)% that will be in the finished wine if wine is fermented dry
the relationship of baume to ethanol is what?
1 - 1.1… eg, roughly the same with 10% variance
what is the symbol/sign for baume?
Be
High pH = ?
low acid
list the baume degrees (Tss - sugar readings) range for the below wines: White table red table sweet table dessert (botrytis)
W: 12-14
R: 12-14
S: 13-16
D: 17-22
list the Total titratable acidity of malic and tartaric acid (T.A. g/L) of the below wines: White table red table sweet table dessert (botrytis)
W: 6-8
R: 5-9
S: 7-9
D: 6-9
list the standard pH of the below wines: White table red table sweet table dessert (botrytis)
W: <3.3
R: <3.4
S: <3.4
D: <3.6
baume is a measure of what?
sugar concentration in grape juice
baume is used in which countries to measure sugar concentration in grape juice’?
Aus and France
what are some other measures of fermentable sugar concentration in grape juice and which nations use them?
Brix = NZ and America Oechsle = Germany and some other parts of Europe.
what is the conversion of baume to Brix?
1 baume = 1.8 brix
what does ppm stand for?
parts per million
what is an “okay” amount of acids in wine? what is a lot?
all per litre
1-2 grams per litre is okay
5-6 grams of acid per litre is a lot
what is o Saccharomyces cerevisiae (S)
a species of yeast
how much fruit was picked at dookie winery?
819 + 720 = 1539
how was the fruit delivered to the winery?
10 kg picking bins
was the machine at dookie a de-stemmer/crusher or a crusher/de-stemmer? why?
de-stemmer/crusher
we wanted to reject stalks and stems because crushing stems may result in more bitterness
what is the approx recovery rate of juice per tonne from the grapes harvested?
1 tonne = 650 L juice
in some white grape varieties you can get 700 L
what is the key difference between early stages of red and white wine production?
Red: skins are kept in must and fermentation happens while in contact with the skins
White: skins are removed for the fermentation process
what is inoculation?
adding good microorganisms to the wine to ward off against spoilage etc
what was the strain of yeast used at dookie?
Vitilevure - Syrah
what is a stuck ferment?
when the wild yeast only ferments must down to about 3/4 baume. hard to restart the ferment and the ferment is only 3/4 done
what changes take place to the must in a ferment?
the temp will rise sugar level (baume) will drop as yeast eat sugars
how much sulphur dioxide SO2 did we add to our must
30 ppm
we added oak chips, what does this do?
they contain tannin so it helps with colour and structure
what is the “cap” in the fermenting must?
the solid mass of skins on top
how much yeast did we add to the must to start fermentation?
150 g added to 500L
why do we plunge and pump-over?
- to oxidise..
- this also keeps the cap wet and extracts flavours and tannins
- also airates “must” to give yeast oxygen
- releases heat - need to do this otherwise yeasts die
what does yeast create during the fermentation process?
- heat
- CO2
- alcohol
what was the baume on the 25/2?
11.8
what is the optimal temp for malolactic fermentation?
20 degrees
how many times a day did we plunge our must?
2
what is hectolitre?
100 litres
what does malolactic fermentation do?
converts malic acid into lactic acid
what were the two types of “press” at dookie?
basket press
Airbag press - compress air (pneumatic)
what is the difference in processes when pressing reds and whites?
reds: you press the fermented must after alcoholic fermentation has occurred
whites: you press the bunches/grapes before fermentation
if you were pressing riesling grapes instead of Shiraz grapes, what sort of press might you use and why?
airbag press
because it allows us to strain/drain juice away from skins
what is the optimal fermenting temp?
28 degrees
why is refrigeration and temp control vital in winemaking?
because it is imperative to controlling fermentation… if ferment is too hot/cold, yeast start to die
what does dookie use to inoculate MLF
direct addition of lactic acid bacteria
what is the required environment before MLF is conducted?
- temp has to be right
- primary fermentation has to be going first
what are the benefits of stainless steel barrels?
- is an inert vessel and can be a closed system with no oxygen
- easy to clean
- good for temp control?
what are the downsides of stainless steel barrels?
- it has to be completely full for it to act as a closed vessel with no oxygen coming in
- while there are variable capacity stainless steel barrels, this can result in them not being the greatest seal long term
in a year, how much wine is lost due to evaporation over long term storage?
5%
what methods are undertaken to maintain the integrity of wine over long term storage
- keep cool
- properly sealing of storage vessel
- topping up
what is classified as long term storage of wine
several months
why does wine need to be kept cool during storage, what is the ideal temp?
ideal temp is 20 degrees
- because heat is the enemy due to oxidization as heat excites oxygen molecules
why are oak barrels used for maturation… what is this referred as?
to get oak characters into the wine
toasting
what are the characters of:
light
medium
heavy toasting?
medium: caramel, vanilla
heavy: chocolate, coffee, smokey, char-rey
what is AO?
American oak
what kinds of oaks are used and what characteristic comes from the respective oak?
French: soft, spicy vanilla
American: coconut
Fine-grain: slow microoxygenation
what else can winemakers do to achieve oak characteristics without storage in oak barrels
add:
- oak chips, planks, cubes, squares, shavings, powder, staves
what is the finest form of filtration? why is it the finest?
sterile filtration…
no microorganisms that will cause spoilage can get through
what is filtration? why do we do it?
passing the wine through various sized filters
- to improve appearance
what is clarification used for? how is it done?
appearance… eg to get rid of cloudy appearance
adding of an agent that will assist with getting rid of the sediment
what is fining?
adding agents such as egg whites that will settle to the bottom of the vessel and take harsh tannins and acids to the bottom to fine the wine
what are the negatives of filtration?
could strip flavour and some thing is unnatural
what is racking?
separating the wine juice from the sediment (skins, lees)
racking off clear juice from sediment
what can harm the quality of the wine prior to and during bottling?
- oxidisation
- excessive heat
- contamination
what are the standard sizes of oak barrels and what are they called?
Barrique - 225 L
Hogs Head - 300 L
Puncheon - 500 L
what are the major pathogens of the grapevine?
what are the major groups of pathogens?
- fungal disease - powdery mildew, downy mildew and botrytis
- Bacteria such as phylloxera
- Viral disease: Eytupa dieback
- nematodes in soil
viruses, fungi, bacteria, protozoa, worms
