1 / 58

VEN124 Section II

VEN124 Section II. Grape and Must Processing. Lecture 4:. Grape Processing. Reading Assignment: Text, Chapter 3, pages 65-79; 91-99.

gizela
Télécharger la présentation

VEN124 Section II

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. VEN124 Section II Grape and Must Processing

  2. Lecture 4: Grape Processing

  3. Reading Assignment: Text,Chapter 3, pages 65-79; 91-99.

  4. In this lecture we will cover the processing steps of crushing/destemming and pressing. The lecture will include a detailed discussion of the issues to be considered when purchasing a crusher/ destemmer

  5. Definition We generally refer to “must” as the material that contains juice, skins and seeds and reserve the term “juice” for the material pressed off of skins and seeds.

  6. Grape Processing: Crushing/Destemming

  7. To Crush or Not Crush? A Matter of Style

  8. Crushing/Destemming • Purpose • Stylistic Options • Equipment Choices

  9. Purpose of Crushing • Better extraction of juice • Better maceration of skins • Opportunity to remove stems

  10. Crushing: Stylistic Options • No crushing • Direct to Press • Whole Berry Fermentation • Carbonic Maceration • Crushing • Temperature • Percentage of Intact Berries

  11. Direct to Press • Minimizes extraction from skins • Used for white and blush wines • Used to reduce/manipulate varietal character • May be used for cryoextraction/ cyroconcentration

  12. Whole Berry Fermentation Clusters are suspended in juice/ethanol Slower fermentation Retains fruit characteristics Juice

  13. Carbonic Maceration Vessel Sealed CO2 Atmosphere Juice

  14. Carbonic Maceration • Berries asphyxiate • Lose some characters due to continued berry enzymatic activity • No ethanol extraction but ethanol is produced by fruit • Develop characteristic flavors of silage and strawberry • Wines do not age well

  15. Whole Berry Fermentation vs. Carbonic Maceration In whole berry fermentation the ethanol produced by yeast penetrates berry inhibiting “decay” reactions seen with carbonic maceration Presence of whole berries during most active phase of fermentation traps volatile aroma characters and prevents loss due to CO2 entrainment, increasing the varietal character of the finished wine

  16. Whole Berry Fermentation vs. Carbonic Maceration In carbonic maceration, the slow process of asphyxiation of the fruit leads to loss of varietal character and the appearance of new characters due to both loss of masking as well as denovo synthesis

  17. Cryoextraction/Cryoconcentration • Use principle behind ice wine production • Freeze grapes to remove water as ice • Freeze grapes to damage skins and improve extraction • Grapes must be processed at low (below 0°C)

  18. Location of Crushing Operation • In the field – as fruit is being mechanically harvested • At winery – raises issues of delivery of undamaged fruit

  19. Types of Crushers • Crusher/Stemmer • Separates stems from crushed fruit • Desirable when: • Stems impart a negative or undesired character to wine • Early stem removal facilitates downstream processing • Crusher/Stem Disintegrator • Breaks up stems along with fruit • Desirable when: • Stems impart positive character • Stems increase yield upon pressing

  20. Crushing: Choice of Equipment We will now consider the factors that should be considered when choosing a crusher/destemmer to purchase

  21. Choice of Crusher • Ease of Inspection/Cleaning • Microbial populations build up on crusher: want little to no juice “reservoirs” • Source of inoculation of entire production • Ease of taking apart/putting back together

  22. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must

  23. Qualities of Must • Hole size: amount of berry damage • Hole surface (smooth or rough?): amount of berry damage • Type of paddle: plastic might not hold up like stainless steel • Clearance between basket surface and paddles: amount of shearing

  24. Qualities of Must (continued) • Rollers: Adjustable? Can they be bypassed? • What % breakage of berries do you want and can crusher deliver that reproducibly? • How much clearance of stems do you want and can crusher deliver that reproducibly?

  25. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery

  26. Rate of Feed vs. Capacity of Winery • Is crushing rate-limiting? • Slow press/tank fill allows: • Oxygen exposure • Growth of aerobes • Loss of volatiles • Slows processing of harvest • Is flow rate from crusher too fast? • Heat from friction • Over shoot tank

  27. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery • Dependability • Breakdown frequency • Ease of mechanics/repair • Type of materials/construction

  28. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery • Dependability • Overbuilt?

  29. Overbuilt? • Will be running at sub-optimal conditions • May not meet specifications/expectations • Increases chances of equipment failure • If remove berries in first third of crusher then the rest of the time the stems are simply being whacked about which will result in the appearance of stem fragments in the must

  30. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery • Dependability • Overbuilt? • Compatibility with Other Equipment

  31. Compatibility with Other Equipment • Using auger, conveyer belt, forklift or hand delivery of fruit to crusher? • How key is uniformity of feed for optimal performance of crusher? • Capacity of must pump

  32. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery • Dependability • Overbuilt? • Compatibility with Other Equipment • Is Adjustment Possible While Running?

  33. Adjustment While Running • Allows for adjustment of must quality without stopping and restarting operation • Berry loss with stems • Seeds being crushed • Stems cracked • Allows for non-uniform juice composition which may increase desirability of final product

  34. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery • Dependability • Overbuilt? • Compatibility with Other Equipment • Is Adjustment Possible While Running? • Service

  35. Service • Spare parts accessibility • Availability of service personnel • Technical expert vs. salesperson • Speed of response • Cost • Operating manual clearly written • Wiring diagram • Trouble shooting guide

  36. Choice of Crusher • Ease of Inspection/Cleaning • Qualities of Must • Rate of Feed vs. Capacity of Winery • Dependability • Overbuilt? • Compatibility with Other Equipment • Is Adjustment Possible While Running? • Service • Portability

  37. Portability • Can Crusher/Destemmer be moved? • How well can it be leveled? • How sturdy is it?

  38. Grape Processing: De-juicing

  39. De-juicing In some cases, it may be desirable to separate the juice from the skins and seeds using a de-juicing tank. This process can occur prior to pressing in white and blush wine production to yield a juice with minimal extraction.

  40. De-juicer tanks Skins and Juice Juice

  41. De-juicing Once de-juicing is complete, the tank is then moved over the press and the must dumped into the press. Continuous de-juicers based on must traveling over a screen are also available.

  42. Grape Processing: Pressing

  43. Pressing • Purpose • Stylistic Considerations • Equipment Options

  44. Purpose of Pressing • To recover juice/wine associated with pulp, skins and seeds that would not be released by simple draining • Can separate press fractions to manipulate juice/wine composition

  45. To Press or Not Press? A Matter of Timing.

  46. Timing of the Pressing Operation Maceration/Skin Contact first: To allow greater extraction of materials from skins prior to removal by pressing Fermentation first: To enhance extraction by ethanol, CO2, and heat of fermentation Stylistic reasons for late pressing: Whole Berry Fermentation Carbonic Maceration

  47. Pressing: Equipment Options • Batch Basket Press Cylindrical Press • Continuous Screw Press Belt Press

  48. Basket Press • Ideal for small volumes • Low yields/High volume loss • Low damage to seeds and skins (minimize extraction) • Uniform pressure difficult • Messy to clean

  49. Basket Press Piston Juice

  50. Cylindrical Presses • Piston • Air Bladder • Vacuum • Easy to control pressure uniformly • Elaborate pressing cycles and separation of juice lots possible • Moderate yield • Somewhat messy to clean

More Related