Different ways in which wood alternatives are produced (sawn, split, etc.) influence the effect of these products on wine. This is suggested by comprehensive results from research undertaken by Jan Swart, researcher/consultant (Wood Scientist), Department of Process Engineering, Stellenbosch University.

Swart explored the requirements of a winemaker regarding wood alternatives, especially where it concerns varying cultivars and vintages. This is part of a Winetech-funded project aimed at evaluating the quality and performance of the diverse range of commercial alternative oak products (AOPs).

Effect of wood anatomy and chemistry

For the past decade Swart has been investigating the anatomy of wood, with a focus on elements responsible for the desirable flavours needed in wine. “A winemaker needs consistency, predictability and repeatability in the flavours from wood. The performance of wood lies within its chemistry and anatomy,” he said.

“Wood anatomical orientation, shape and size of AOPs must be considered for maximum extraction of desired flavours. He pointed out that the initial choice of a comminution process (which means to reduce to smaller fragments) influences the extraction from and the performance of oak alternatives.

In the investigation rotary-cut veneer was used as the starting material for AOPs. ”Veneer allows for the improved utilisation of resources, and the AOPs were uniform in anatomical orientation, shape and size. This approach enabled the maximum utilisation of the tree’s natural transport system, leading to significant extraction gains,” Swart continued.

“With rotary cut veneer the production yield per log was maximised and there were less waste. The resultant AOPs have up to two to three times higher extraction tempos, yielded up to double the total amount of extracts and this was attained in significantly shorter extraction times,” Swart explained.

Influence of comminution technology

Natural variation is part of the game in the production of natural products like wine and AOPs. ”Wood is a biological material with wood anatomical and chemical variation. How do you manage that?” asked Swart. The rotary-cut veneer in itself brings improved uniformity and enhanced wood flavour consistency, repeatability and predictability in AOPs.

“Most winemakers get the first introduction to a product through a sample, which is then generally evaluated in terms of wood flavours, in a small volume of wine” he commented. Swart went on to encourage winemakers to obtain as much information as possible regarding the origin and the production processes used. 

Sustainability

According to Swart, first-grade trees currently used for barrels and oak alternatives are becoming a very limited resource. The results obtained from the investigation highlighted the potential and importance of utilising second-grade trees as raw material for the production of high-quality wood alternatives. These are trees regarded as unsuitable for stave production, but the wood flavour quality is perfect for AOPs.

With a global call for the conservation of trees, this concept will ensure that trees that are generally considered not to be usable can actually be used in the production of AOPs. The rotary-cut veneer approach also contributes to financial, sustainability and yield benefits, such as:

1. Substantially reduced raw material costs
2. More trees from a forest can be utilised, which is sustainable and green-oriented
3. More logs can be cut from a tree, which increases the yield per tree
4. Significantly higher oak alternative yield per log
5. Substantially smaller ‘inaccessible inner volumes’ present in all oak alternatives, which will reduce waste

He concluded by saying that this new generation of oak alternatives produced by using the rotary cut veneer process, is a precision-engineered product that can be produced from a more sustainable wood source. 

”With such a paradigm shift, wineries will be in more control, not only of what they buy, but also of how to best utilise alternative oak products.” ended Swart.

Contact:

Wood Flavour Innovations

Jan Swart

[email protected]