Wine Processing

Explain the primary and secondary fermentation during the red wine production.

after harvest, red wine is held in vatts to do the primary alcoholic fermentation, then drained, then fermented again.

What is the major difference in the process of making red and white wine (apart from the different grape varieties used)?

after harvest, red wine is held in vatts to do the primary alcoholic fermentation, then drained, then fermented again. white wine is only fermented at the end

What is the difference between wine and must?

wine is beverage from alcoholic fermentation of fresh grapes, whereas must is the liquid product from fresh grapes via crushing, pressing, etc but without alcoholic fermentation

Summarize the main points of winemaking (starting after harvest) in a shorthand fashion.

1. mechanical harvest treatments- destemming, crushing, tank filling 2. maceration 3. draining (separate wine and pomace by dejuicing and pressing) 4. alcoholic fermentation

Define organic wine.

Organic wine is wine made from grapes grown in accordance with principles of organic farming and processed under organic oenological practice

Explain the differences between fermentation and malolactic fermentation!

- different types of bacteria! - malolactic depends on the climate- cool yes, warm no! - fermentation happens in presence of oxygen in general

What is decisive for the taste of the wine? (Write at least three influences).

- grape variety - age of vine plant - wine cellar technology - geology, mineral content, topology, climate

What is malolactic fermentation? What is it good for in wine making?

- performed by lactic acid bacteria - biological degradation of acidity - desirable in cool climates where wines with a high acid content are produced

What is the point of using sulfur dioxide in wine making?

- restricts the growth of microorganisms, elimates some off-flavours, acts as antioxidant and suppresses oxidized odours

What is alcoholic fermentation? Which organisms conduct it during wine production? How is it conducted? What are its major and by-products? Explain.

= biological process in which sugars such as glucose and fructose are converted into cellular energy, producing ethanol and carbon dioxide as metabolic waste products - saccharomyces cerevisiae are the most common fermenting yeast - ferments in the presence of oxygen - most important byproducts: acetic acid and glycerol - high sugar content = high byproduct content

What is maceration?

= enzymatic breakdown of grape cell after crushing or pressing - releases tanins and other intracellular compounds into juice - white wines are limited maceration time - red wines have prolonged vatting time parallel with fermentation

What is Botrytis cinerea and why is it important for winemaking?

= fungus - limited infection of ripening grape - noble rot is WANTED, but bunch rot is UNDESIRABLE - creates sweet and expensive wines! - creates dry berries with increasing sugar concentration, changes in aroma compounds, increase in glycerol

List the steps of vinification!

Vinification is the process of turning grapes into wine. Grapes naturally possess everything that is needed to make wine and in natural wine, ripe organic grapes are the only ingredient.

List both positive and negative effects of green covering in vineyards!

creating a canopy microclimate that restricts disease development

How is harvest done, and what determines which way it is done?

determined by the ripeness of the grape (sugar, acid, tannin levels) - manual - vs. mechanical

What is the difference between spontaneous and inoculated fermentations? What are their advantages and disadvantages?

inoculated= guided wine fermentation: added active yeast culture to activate primary fermentation - actively growing starter culture dominates the native yeast species present in the grape must - gives a choice in yeast strains and therefore consistency of wine characteristics, but less interesting spontaneous= natural wine fermentation: various yeasts and other microbiological species present in grapes ferment. saccharomyces cerevisiae predominant in later stages - gives wine with distinct sensory quality but often more variable outcome and higher possibility to spoil