Ch 7 - Grape Processing And Adjustments Flashcards
Why might grapes be sorted on arrival at the winery?
To eliminate unripe or rotten grapes if they are destined for a premium wine?
Why might grapes stems be removed from hand-harvested grapes? How is it done?
The stems contain tannins which the winemaker may not wish/ need for the wine. A machine is used which can often also crush the grapes.
What does crushing do and what should be avoided? What is the juice called?
Crushing breaks the skins and releases some juice. Breaking the seeds should be avoided as they contain bitter oils and tannin which can make the wine bitter and astringent. The juice from this process is called free run juice.
What is pressing? When is it done for white/red wines?
Pressing separates the liquid and the solid constituents of the grape. For white it is done before fermentation - for red it is after fermentation.
Why should pressing be gentle? What is the juice called?
To avoid breaking the seeds and releasing bitter oils and tannins. The liquid is known as press juice.
How might gentle pressing be done nowadays?
Using modern techniques such as pneumatic press which can be carefully controlled.
What are press fractions?
The juice from the start of pressing is different in flavour and texture from that at the end. The winemaker may separate the juice into fractions and treat them individually and use as blending later.
What are the three main adjustments to must and/or wine? When can adjustments be made?
Sugar and abv - Before during or after fermentation subject to regional legal requirements.
Acid - Acidification and deacidification
What is must? What is must weight?
Grape juice. Must weight is the level of sugar in the juice.
When might sugar be adjusted?
In cooler climates where there is insufficient in the juice to obtain the required alcohol level.
What is enrichment?
This is the process of increasing sugar levels ( so as to create more alcohol) by adding a colourless, odourless, tasteless liquid called Rectified Concentrated Grape Must (RCGM) before or during fermentation.
What effect does enrichment have?
It increases the sugar level so there is enough for the yeast to convert to the required alcohol level in the wine.
Does enrichment benefit wine?
Where legally permitted and carried out properly it can give a better wine. If abused it can produce a wine that tastes hard and thin, as there there are insufficient fruit flavours to balance artificially elevated alcohol.
What is chaptalisation?
Where sugar from sources other than grapes is used, eg sugar beet, this known as chaptalisation.
What effect does removing water from the juice have?
Concentrates remaining sugars, flavours, acid, tannins and any faults. Also lowers volume so less wine will be produced.
