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WSET Diploma: Unit 2 > Vini 1: Harvesting and Processing > Flashcards

Vini 1: Harvesting and Processing Flashcards

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1
Q

Pre-vintage planning:

A

ECP - Estimation (of crop levels), cleaning (of necessary equipment) and purchasing (of oenological products).

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2
Q

Pros and cons of hand harvesting:

A

Minimal damage to bunches, selection of best grapes (whole bunch, carbonic), any terrain style and little equipment needed. BUT, slower and higher labour input. Can be obligatory by law.

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3
Q

Pros and cons of machine harvesting:

A

Speed/intervention (use of fibreglass rods), night harvesting and labour costs reduced. BUT, grapes damaged (oxidation risk), less selection, machines pricey/in high demand, needs suitable trellis, wide rows and not suitable for some terrain.

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4
Q

Limiting fruit damage in transit:

A

Shallow picking containers, limiting container transfers, reducing load levels, refrigerating trucks and minimising delay before processing.

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5
Q

Minimising oxidation risk:

A

Blanket grapes (CO2, N), add SO2, harvest at cool time (morning or night) and minimise delays.

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6
Q

Contamination causes:

A

Dilution (rainfall), leaves/stalks in bins, picking shears left behind, MOG and soil/oil/taints in bins.

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7
Q

Why is grape processing more efficient in white winemaking?

A

Because the fruit is de-stemmed.

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8
Q

Why are stems sometimes undesirable in red winemaking?

A

Because they release water and potassium and they absorb colour and alcohol.

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9
Q

Downsides of de-stemming (whites):

A

Machine damage, slower pressing (no natural drainage channels) and juice not as fine (for same reason).

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10
Q

Downsides of de-stemming (reds):

A

Harder to control temp./phenolic extraction, don’t get the good tannins found in some stems and slower pressing.

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11
Q

Objective of crushing:

A

To release juice that is immediately available to yeast for fermentation.

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12
Q

Crushing (reds and whites):

A

Faster for whites (free-run juice available immediately). Increased colour and tannin extraction for reds.

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13
Q

Grape which sometimes has to have semi-carbonic maceration by AC law?

A

Carignan

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14
Q

Heat exchanger:

A

Chills white grapes before pressing.

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15
Q

Good extraction level at pressing:

A

ca. 70% of total weight.

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16
Q

Skin contact in whites:

A

Pectolytic enzyme often added to help extraction. 5-10 degrees for up to 24 hours.

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17
Q

Pros and cons of basket press:

A

Simple, produces clear must/wine. BUT, slow, labour-intensive, can release bitter phenols and oxygen exposure.

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18
Q

Pros and cons of horizontal screw press (e.g. Vaslin):

A

Easy to fill and empty, automated and blanketing possible. BUT, can be violent (over-extraction) and high pressures can reduce quality.

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19
Q

Pros and cons of pneumatic press (e.g. Willmes):

A

Good extraction and more gentle. BUT, slower.

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20
Q

Pros and cons of tank press:

A

Can be flushed with inert gas, good extraction. BUT, slower and most expensive of all.

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21
Q

Pros and cons of continuous screw press:

A

Very high, uninterrupted throughput and modifications can be made in output tray. BUT, produces lower quality juice/wine through rough action.

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22
Q

Purposes of sulfur dioxide (SO2):

A

Antiseptic, antioxidant, antioxidasic (denatures oxidising enzymes) and combines with acetaldehyde.

23
Q

Recommended SO2 amounts:

A

White musts: 60-100mg/L. Red musts: 10-60mg/L.

24
Q

SO2 for higher pH wines:

A

Need more because less is in the active form.

25
Q

Maximum SO2 from 2009 vintage:

A

Dry reds: 150mg/L (contain natural antioxidants). Dry whites: 200mg/L. Sweets can have higher levels, due to binding powers of sugars.

26
Q

Pre-fermentation clarification (white and rosé):

A

Cold settling, centrifugation, diatomaceous earth filtering or flotation.

27
Q

Cold settling:

A

Very common. Must left to settle (often overnight) at cool temp. (5-10 degrees). Gravity sends suspended solids to bottom and can then be racked off. Possible addition of pectolytic enzymes - destroy pectins that suspend the grape flesh in the must.

28
Q

Centrifugation:

A

Use of centrifugal force. Considered harsh by many. Expensive and oxidation risk also high. Used in big wineries where efficiency is key.

29
Q

Diatomaceous earth filtration:

A

Good for aromatic varieties. BUT, complete solid removal can reduce must’s nutritional content, meaning yeasts struggle to start fermentation.

30
Q

Flotation:

A

Bubbling nitrogen/CO2/air through cloudy must to catch solid particles. Removed by rotary suction device at top. Hyperoxidation can happen simultaneously. BUT, fermentation makes wine turbid again, so more clarification needs to happen again later.

31
Q

Enrichment with sucrose (beet/cane):

A

Thought to be most neutral and cheapest. Each kg of sugar increases overall wine volume by 0.63 litres. Sucrose mustn’t be dissolved in water before being added to must.

32
Q

Sugar and alcohol (white wines):

A

Raising abv. by 1% requires 17g of sugar per litre.

33
Q

Sugar and alcohol (red wines):

A

Raising abv. by 1% requires 19g of sugar per litre. Higher level of evaporation at higher temps. and in pumping over.

34
Q

Vacuum evaporation:

A

Water in must evaporates at just 20 degrees. Flavours and aromas protected. Reverse osmosis more popular.

35
Q

Reverse osmosis:

A

Uses differences in molecular weight. Selective membrane filter used with pressure applied. Concentrates acids, flavours and tannins, BUT, everything (inc. bad stuff) is concentrated. Also used in finished wines to remove excessive alcohol or VA.

36
Q

Cryoextraction:

A

Replicating the natural on-vine freezing process. Concentration by freezing water (grapes or must). Controversial.

37
Q

EU rules:

A

Actual alcohol content no lower than 8.5%. No enrichment by 2% potential alcohol/maximum reduction in volume of 20% (whichever is lower). Only one enrichment method allowed.

38
Q

Definition of potential alcohol:

A

The concentration of alcohol that would result from the fermentation to dryness of all the sugar dissolved in a given must.

39
Q

Permitted de-acidification methods:

A

Addition of potassium bicarbonate (pre-fermentation), addition of calcium carbonate (forms calcium tartrate), double-salt (pricey, blend of calcium carbonate and calcium tartrate-malate) and MLF.

40
Q

Risk in de-acidification:

A

pH increases, risking microbial infection and reduction of effectiveness of SO2.

41
Q

pH scale is…

A

Logarithmic - see page 101.

42
Q

EU limits on tartaric acid:

A

1.5 g/L in musts, 2.5 g/L in wine.

43
Q

Best time for acid adjustment:

A

Just prior to fermentation to achieve better integration.

44
Q

Why is citric acid never added before fermentation?

A

Because it can be metabolised by yeast and bacteria to form acetic acid, thereby lifting VA.

45
Q

Bentonite:

A

A form of clay used as fining agent. Removes dissolved proteins. Usually used after fermentation. Non-selective (removes flavour compounds too), so to be used sparingly!

46
Q

When might flavour and colour enhancing enzymes be added?

A

At the time of the crushing operation.

47
Q

Two important oxidases (enzymes catalysing oxidation):

A

Laccase and tyrosinase.

48
Q

Laccase:

A

In fruit infected by grey rot. Turns must brown and does away with aromas. Solution is to avoid mouldy grapes or pasteurisation (65-70 degrees) to destroy it.

49
Q

Tyrosinase:

A

Found in healthy grapes. Controlled by adding SO2.

50
Q

Why are copper and bronze avoided in modern winery equipment?

A

Because they are two metal ions that act as inorganic oxidasic catalysts.

51
Q

Benefits of hyperoxidation:

A

Varying degree of colour stabilisation and addition of complexity. Not recommended for Sauvignon Blanc.

52
Q

Dangers of hyperoxidation:

A

High levels of acetaldehyde (ethanal) produced giving a flat, sherry-like flavour. Bitter-tasting components produced from oxidised phenolics. Spoilage bacteria produced - e.g. acetic bacteria.

53
Q

Ascorbic acid also known as…

A

Vitamin C

54
Q

Ascorbic acid used as…

A

An antioxidant that supplements the role of SO2. BUT, has NO antiseptic effect, so can’t replace it entirely. Also, without SO2, it forms hydrogen peroxide (bleaching agent)!

WSET Diploma: Unit 2 (8 decks)

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