Effects of must turbidity on fermentative aroma development in Sauvignon blanc

• Author(s): Herrmann, Lukas Karl
• Date: 2016
• Persistent ID: http://hdl.handle.net/10400.5/13010
• Origin: Repositório da UTL
• Subject(s): Sauvignon blanc; must turbidity; fermentative aroma
• Document Type: Master thesis
• Language: English
• Advisor(s): Grose, Claire; Silva, Jorge Manuel Ricardo
• Contributor(s): Repositório da Universidade de Lisboa

Description

Mestrado Vinifera Euromaster - Viticulture and Enology - Instituto Superior de Agronomia - UL / Institut National d'Etudes Superieures Agronomiques de Montpellier

In many ways New Zealand has become an ideal for a New World wine country. With the first commercial Sauvignon blanc only released in 1974, Sauvignon blanc fought its way to become not only the flagship of New Zealand`s wine industry, holding around 66 % of the country’s total grape production at the 2015 harvest, but also made its way to be recognized for its outstanding quality all over the world. For some critics, New Zealand Sauvignon blanc is arguably the best in the world and others called the Marlborough wine region the best place to grow Sauvignon blanc in New Zealand. Even though testimonies like that may be subjective as taste lies on the tongue of the beholder, New Zealand Sauvignon blanc clearly came a way plastered with success leading to an export value of $1.424 billion NZD in 2015. Key to this success is that the industry found a way to distance itself from its French archetype, world famous Sauvignon blanc originated from the Loire valley, and reinvented itself, introducing a unique winestyle that does not need to shy any comparison. In the heart of this winestyle aroma compounds of the thiol group play an important role. Derived during yeast activity during fermentation from non-odorous precursors found in grapejuice, the two most important thiols that have been related with Marlborough Sauvignon blanc are 3MH and 3MHA. These deliver exotic nuances reminiscent of grapefruit, passionfruit, gooseberry, guava and boxtree. Due to the high oxidability of thiols, several strategies have been adapted by the industry to preserve these key compounds and their non-odorous precursors during the processing of grapes, which includes harvesting, transportation, processing and storage. Although a lot of research has been carried out to further understand the relations between precursors, thiols and their preserving, and to be able to continuously contrast New Zealand Sauvignon blanc from competitors, many questions still remain unclear at the present day. One of them is the effect of juice turbidity on aroma development during fermentation. Research has revealed a broad idea on the positive and negative effects, caused by micronutrients and physical parameters of grape solids derived during process steps leading to juice extraction from the berries on fermentation kinetics and general aroma development. To my best knowledge no research has been published to the present day that focuses on the effect of juice turbidity on the thiol development and expression in Sauvignon blanc ferments. This masterthesis in hand, with the title “Effects of must turbidity on fermentative aroma development in Sauvignon blanc” is supposed to give an overview over the state of research on Sauvignon blanc with a further focus on the question about possible effects and practical applications of juice turbidity. Finally, this work tries to improve the small scale winemaking protocol of Plant and Food Research, Blenheim, where this research has been conducted.