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26 Cards in this Set
- Front
- Back
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What is 'must' and from what latin word is it derived?
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Must is the product of the crush. Therefore, know that in red wine production, it refers to the juice as well as the skins. It come from the latin word 'mustum' which means new or fresh.
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In addition to the fact that stalks are a rich source of tannin, what other benefit do they offer in terms of the winemaking process?
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Stalks can act as useful drainage channels during pressing.
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Describe how a de-stalking machine works.
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A de-stalking machine is a horizontal perforated drum with rotating blades. Bunches are fed into the rotating drum where the blades will cause the berries to fall through the perforations and onto a conveyor belt.
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After the stalks have been collected from the de-stalking machine, what is a tactic that ecologically minded producers might employ to process them?
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They may chop and soak the stalks in water to extract the sugar to ferment to a weak liquor which can be distilled and subsequently used for fortification.
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Contrast the process of crushing with the process of pressing.
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Crushing simply endeavors to rip the grape open to allow free-run juice to flow. Pressing is the extraction of the remaining juice.
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What is a pectinolytic enzyme and how is it used in the crushing of grapes?
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A pectinolytic enzyme is an enzyme capable of breaking down the gelatinous enzymes in the pulp which will release more juice from the sticky mass.
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What enzyme would a winemaker add to the pressing stage to attempt to coax more juice from the pulp?
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A pectinolytic enzyme.
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Describe two different methods of draining juice from the crush.
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One is called a static drainer where the juice is gently allowed to percolate through the mass of skins. The disadvantage of this method is that it is very time consuming. Another method is through a mechanical drainer equipped with a rotating screw. This method alleviates the time requirement of the static drainer, however there is greater disturbance of the skins and thus, a more noticeable polyphenolic extraction.
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For white wine, how much free run juice can be obtained from one tonne of grapes?
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400-500L
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Contrast the time of pressing between white wine production and red wine production.
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White wine will be pressed after the crush and red wine will be pressed after the fermentation.
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Describe how a basket, or a vertical screw press works.
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By screwing down the lid of the press, you increase the pressure on the mass causing a release of the contents of the mass.
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Name three disadvantages of using a basket press.
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The process is very time consuming. The way that the juice trickles out allows oxygen to be dissolved from the atmosphere. To clear and reset the press is quite labour intensive.
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Name a famous chateau that employs the basket press.
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Chateau Petrus.
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Name an advantage of a basket press over the more modern presses.
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The static bed of skins in the basket press acts as a very fine filter and the juice is of incredible quality and great clarity.
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In champagne production, why would the basket press employed be shallower with a greater diameter?
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The greater diameter allows the juice to be liberated from the skins as quickly as possible to minimize the extraction of colour from black grapes.
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What is a Vaslin press?
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A Vaslin press is a horizontal basket press given two pistons, one at each end of the perforates cylinder. It rotates and the two halves are drawn together. Stainless chains connect the pistons and are capable of breaking up the must once the pistons have receded back to their original sides.
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Fundamentally, a Vaslin press will enact two different methods of juice extraction from the grapes. Describe them.
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The initial rotation of the device will allow free-run juice to be filtered. The action of the pistons will extract juice, flavours, and compounds that were contained in the tougher inner cells of the pulp.
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Name the company that developed the pneumatic press.
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The Willmes company.
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What is the fundamental advantage of the pneumatic press over the vaslin press.
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The pneumatic press delivers pressures that are much gentler to the must of the grapes resulting in less abrasion of the skin and superior quality juice.
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In terms of its design, contrast a vaslin press from a pneumatic press.
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While both are focussed horizontally, a vaslin press relies on pressure coming from pistons delivering pressure from the sides whilst tumbling. A pneumatic press is designed around a gentle pressing from an inflatable bag in the middle or the bottom of a horizontally positioned tank.
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What is a drawback of both the pneumatic and the vaslin presses?
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Both are susceptible to oxidation.
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What is a tank press and how does it solve the drawbacks of both the pneumatic and the vaslin presses?
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A tank press is a pneumatic press that exists within a closed tank that can be pre-flushed with nitrogen to ensure a completely anaerobic environment.
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What is a drawback of the tank, vaslin, and pneumatic press?
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Each of these presses, though progressively more advanced, each deal with the same problem that they are still dealing with batch processes. Therefore, they need to be emptied, cleaned, and reloaded after each use. For large wineries, this is costly.
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Describe the operation of a continuous screw press.
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A continuous screw press is a perforated steel tube that contains an archimedes screw that pushes grapes through the pipe.
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What is a drawback of a continuous screw press?
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Due to its design, it exerts immense pressures on the must and produces pretty low quality juice.
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How was the design of a continuous screw press modified to produce acceptable quality juice?
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Movable troughs were added below the perforations so that juice escaping at different sections of the tube could be separated.
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