By HENRY WORK


The use of oak alternatives, or adjuncts as they are sometimes called, to flavour wine is neither a new concept nor particularly limited in its applications. 

On a commercial basis, as early as the 1970s, American oak sawdust was available as a product called Oak-Mor. 

By the 1990s, Gallo, the huge California wine producer, was purchasing more than a half-million kilos of oak chips a year to flavour some of their wines. At that point, the chips were toasted to reduce the greenness, as the wood was direct from the stave mill yard; but packaged in permeable bags, subject to environmental degradation. 

Fast forward to 2008, and the oak alternatives have advanced to the sophistication of premium food-grade products. The oak is carefully monitored as it is air-dried; computers control the toasting temperatures, and the products are packaged in weather-proof containers. 

In New Zealand, there are at least twelve suppliers of oak alternatives; and world-wide, hundreds of wineries are using the various formats of oak adjuncts. This article will briefly discuss what is currently available and how it is being used.

All about surface area
Oak alternative products are now available in many forms and sizes ranging from liquids, to powders, granular, chips, beans and cubes, to stave-like slats of varying thicknesses and lengths, which fit into barrels and tanks. 

The oak uptake, and its interaction with the wine, is most rapid with the finely-sized pieces (powder, granular and chips). Larger formats (beans and staves) provide for slower integration, and therefore more control for the winemaker. This is especially helpful with the lighter style of many Kiwi wines. 

The raw materials for today’s oak alternatives are processed with the same attention to quality and flavour nuance that is applied to production of fine wine barrels. Options include: 

• the source of oak (French, American, Eastern Europe)  
• choice of plain or toasted by several methods – oak fire (radiant), infrared, and hot air (convection heat) - and amount of toast
• length of air-drying (typically one to three years)
  air-drying with or without additional water immersion
• grain tightness
• and subtleties such as how rough the pieces are cut, which can increase or decrease the surface area.

Mark Roberts, the Oak Solutions Specialist at OAK, notes that, as with wine barrels, customised toasting of the oak alternatives is now available. evOAK and other suppliers offer an array of products designed to bring out the various flavour components within the oak. Used individually, or in combination, they can add spice to the wine or enhance certain wine aromas and tastes.

Application
Different oak adjuncts can be used at various steps within the wine making process.
During picking, fine oak powder or granules can be sprinkled on the grapes in the picking bins or at the crusher to reduce ‘greenness’ and help slow the oxidation process. Anne Batley-Burton, of Regency Imports, recommends between 300 to 500 grams per tonne when using their Pronektar French oak powder for this stage. 

A common method of use for oak alternatives is during tank fermentation of both red and white wines. ‘Tea bags’ containing chips, beans (centimetre cubes) or slats are placed in tanks during the fermentation process.

According to Mike Brown, winemaker and general manager for Nelson-based Waimea Estate, they use the beans in food-grade polyethylene bags, at a rate of 75 grams/hectolitre while fermenting their Spinyback Chardonnay.

Phil Jones, managing director and senior winemaker for Spencer Hill, has told Wine Technology magazine that he ferments pinot noir using bundles of staves, from several suppliers, held in place in tanks by tie-downs. Having used oak alternatives for fifteen years, all the winery’s tanks are equipped with in-tank fittings to secure the staves. Waimea Estates uses a similar system when fermenting cabernet franc and shiraz. For both wineries, the oak adds structure and colour to their wines. 

Oak chips and staves used during fermentation can also reduce vegetal aromas. This is particularly helpful when grapes have to be picked early due to impending rain, or when labour shortages or other logistical problems prohibit picking a large crop at optimum timing. 

In another variation, Robinson (2006) mentioned that staves, impregnated with lactic acid bacteria, are available to start a ‘softening’ secondary malolactic fermentation; although that product was not seen in the New Zealand/Australian supplier literature.

Barrel inserts were developed in the early 1970s by, among others, Custom Cooperage of California. Now, as then, they consist of a food-grade plastic frame on to which about twenty-five toasted slats are attached. To install, the head of the barrel is removed, the insert secured within the barrel, and the head replaced. At a cost of around $100 each for material and labour, this is considered by some winemakers an economic alternative to new barrels, and a reasonable facsimile to the oak integration process provided during barrel ageing. 

As an example of the volume of usage of barrel inserts in certain regions, Columbia Crest, a Washington State (US) winery, adds inserts to 10,000 French and American oak barrels every couple of years for barrel ageing of both chardonnay and their red wines.

Another product, typically a series of small staves or sticks that are tied together - or in connected net bags - can be slipped through the bung hole of the barrel. This method is easier to install than the inserts, but makes washing the barrel difficult unless the sticks are first pulled out. A variation on this theme is a spiral of oak, which dramatically increases the surface area, and can be inserted through the bung hole.

Placing larger slats/staves in stainless steel tanks was the next step in the evolution of oak alternatives. As noted, Spencer Hill uses a combination of rough and smooth-sawn tank-insert staves to provide a hint of oak for their pinot noir; renewing the oak with each vintage. Splash-racking the wine several times adds an amount of oxidation, and the wine may be stored for up to 14 months on these staves. 

Wine placed in these barrels with inserts, or in tanks with staves, takes longer for the oak uptake than with chips or beans, and generally the winemakers see a better integration of the oak flavors. This can be modified somewhat by the thickness of the oak pieces which helps determine the ageing characteristics – the thicker the piece the slower the uptake of the oak.

Micro-oxygenation (micro-ox) was developed in the Madiran region of France in the 1970s (Work, 2007), and now has widespread use in California, France, and elsewhere, especially in conjunction with oak alternatives. As the cost of fine oak barrels continues to rise due to exchange rates and manufacturing costs, for large-scale winemaking and cost-containment, the use of oak alternatives with micro-ox in stainless steel tanks is a serious contender to the more traditional methods. 

Tony Robb, senior winemaker at Corbans, noted that they use the Boisé France brand oak chips during the ageing of some of their white wines, and in conjunction with micro-ox when ageing some red wines. As with many wineries, the oak alternatives constitute only one segment of Corbans’ total oaking and ageing processes.


Hiding from view
Several winemakers contacted for this article indicated that they were using or experimenting with oak alternative products, but did not want to speak on the record about those activities. In this author’s opinion, the main reason for this reluctance seems to be the wine writer’s and wine critic’s sense of what is ‘acceptable’ or ‘romantic’ winemaking rather than any food safety or taste-factor concerns. True, some inferior wine was made with raw or un-toasted oak ten or fifteen years ago; however, the products and their use have vastly improved. 

Should oak alternatives as a production tool be kept in the dark? No, we do a disservice to customers by hiding wine-making techniques that are not proprietary. Other than on a tour of the winery, few customers are concerned about how the wine is made, as long as it is produced safely. Wine writers and critics need to evaluate wines made with oak alternatives with an open-mind, and to be honest with the wine consuming public.

If you are considering using oak alternatives – a point emphasised by Batley-Burton, Roberts, and all the winemakers consulted for this article - is that each winemaker must find what forms and amounts fit her or his wine style. The general dosage recipes prepared by the suppliers must be tailored to each wine and winery. 


Conclusion
The various oak alternatives have improved dramatically over the past forty years, and they can be used in most stages of winemaking. For certain wines, they make economic sense. Like any other tool in the winemaker’s palette, experiment well ahead of when they might be needed.

(Article by Henry Work: Henry.work@wineconsulting.co.nz)



References:

Robinson, J. (2006, May 8). Now that oak chips etc may be used throughout Europe… From the web site of Janice Robinson. Retrieved September 2, 2008 from www.jancisrobinson.com

Work, H. (2007, November/December). Micro-oxygenation: Innovation for the winemaking toolbox. Practical Winery, pp. 34, 36-38, 40-42, 44-46.