Optimisation of wood flavourants for the production of quality wines through improved wood production strategies, with special emphasis on alternative wood products

Project Number
US WS 01

Project title
Optimisation of wood flavourants for the production of quality wines through improved wood production strategies, with special emphasis on alternative wood products

Project leader
Rypstra, T

Institution
University of Stellenbosch

Team members
Swart, J

Project description
Currently, the use of alternative wood products such as staves, chips, powder and wood extracts, to provide oak fragrance in winemaking, is in a developmental stage but is, because of its economic and technological benefits, rapidly gaining acceptance in the South African wine industry. As with barrels, a need exists to develop the use of these products i.e. the technologies, on a scientific basis. The objective of this project is to gain an insight into the present role of wood in winemaking by first verifying the current benchmark status of the standard oak barrel (wine in wood) and then to extrapolate this knowledge to alternative products (wood in wine). The findings of this report and deliverables of the first year of this project are based on direct communication with selected manufacturers and suppliers, and users of barrels or alternative products, as well as the result from a literature study.

The criteria whereby wine barrels are bought and sold in South Africa are in terms of material properties (species, provenance, grain, part and age of the tree, etc.) and processing properties (timber log breakdown, drying, barrel manufacture and toasting methods). The current criteria appear to work on the winemaker and cooperage interface. However, the winemakers flavour requirements in terms of chemical substances required from the wood are at best, indirectly specified in terms of physical wood properties. Because of the large number of complex and interrelated criteria, a need exists for more scientific, extensive and statistically acceptable information. The inevitable use of cooperage wood from non-traditional provenances and regions requires scientific scrutiny and approval. Reliable techniques such as DNA tests reported in an European Union sponsored study, are required to control the provenance of wood.

Serious need for transfer of existing knowledge on the role of wood in barrels and alternative products was expressed by individuals interviewed.

Some similar and different physical and processing parameters of the alternative products to barrels were identified confirming the existence of the specific alternative product technology. The geometry and shape, drying and toasting processes, wine/oak mass ratios, stage and duration of oak flavour addition, were considered. Limited scientific information on alternative products could be obtained from literature searches.

The use of wood alternative technologies can effectively be regarded as the addition of wood-borne (chemical) additives. The wording in Act 60 of 1989 as amended 7 March 2003 is written in such a way that it allows and encourages responsible experimentation with wood and tannins. The possibilities and limitations, and possible transgressions of the law, can only be debated on the basis of sound technical and scientific information.

Article
Theron, C W, Rypstra, T, Swart, J P J. 2006. The cleaning and re-use of barrels, WineLand, Mnth Aug (p. 87)

Theron, C W, Rypstra, T, Swart, J P J. 2006. Timber imports cost the wine industry millions, WineLand, Mnth May (p. 67-68)

Theron, C W, Rypstra, T, Swart, J P J. 2006. The necessity of timber specifications, WineLand, Mnth Jun (p. 76)

Theron, C W, Rypstra, T, Swart, J P J. 2006. Specific barrels for specific cultivars, WineLand, Mnth Sep (p. 105)

Theron, C W, Rypstra, T, Swart, J P J. 2006. The use of different size barrels, WineLand, Mnth Nov (p. 70)

Theron, C W, Rypstra, T, Swart, J P J. 2006. Factors influencing the impact of oak chips on the flavour of wine, WineLand, Mnth Dec (p. 67)

Theron, C W, Rypstra, T, Swart, J P J. 2007. Recycling used wine barrels, WineLand, Mnth Mar (p. 57)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The use of American oak barrels, WineLand, Mnth Apr (p. 48)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The influence of oak on the vinification and maturation of wine, WineLand, Mnth May (p. 60)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The use of oak in the vinification of flagship wines, WineLand, Mnth Jun (p. 72)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The increasing use of alternative wood products, WineLand, Mnth Jul (p. 73)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The flavour contribution of wood to wine, WineLand, Mnth August (p. 78)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The certification of oak products used in the vinification process, WineLand, Mnth Dec

Theron, C W, Rypstra, T, Swart, J P J. 2007. The use of heat and water in the construction of barrels, WineLand, Mnth Oct (p. 77)

Theron, C W, Rypstra, T, Swart, J P J. 2007. The use of high-power ultrasonics to clean and sanitise barrels. WineLand, Mnth Nov

Theron, W C, Rypstra, T, Swart, J P J. 2007. The influence of toasting and particle size, WineLand, Mnth Sep (p. 109)

Theron, C W, Rypstra, T, Swart, J P J. 2008. Selecting the right wood for a wine style, WineLand, Mnth Jan

Theron, C W, Rypstra, T, Swart, J P J. 2008. The different alternative wood products, WineLand, Mnth Feb

Theron, C W, Rypstra, T, Swart, J P J. 2008. Using American oak of different origin, WineLand, Mnth Mar

Theron, C W, Rypstra, T, Swart, J P J. 2008. Micro-oxygenation. Part I, WineLand, Mnth Apr

Theron, C W, Rypstra, T, Swart, J P J. 2008. Micro-oxygenation. Part II, WineLand, Mnth May

Theron, C W, Rypstra, T, Swart, J P J. 2008. Cleaning and disinfection of oak barrels and oak adjuvants with high-power ultrasonics, WineLand, Mnth June

Theron, C W, Rypstra, T, Swart, J P J. 2008. Effective oak maturation of wine, WineLand, Mnth Jul

Theron, C W, Rypstra, T, Swart, J P J. 2008. Selecting the right wood for a wine style, Wynboer Technical Yearbook, (p. 108)

FinalReport.pdf

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