June 2009 Issue of Wines & Vines

The Art of Oak: Part 2

Use of oak alternatives in modern winemaking

by Dr. Richard Carey
Alternative text
Furfural content in cube-extracted wine in a four-month period was significantly increased.

  • Carey considers the sensory aspects of various oak alternative products and reviews the ways his fellow winemakers use them.
  • Oak alternative products are like any tool. The more control that tool allows a careful artist, the better that artist will be.
  • Careful winemakers should not be afraid of using these products in their whole line of wines.

In the April, 2009, issue of Wines & Vines, I discussed components in the various types of alternative oak and focused on the constituent analysis of the various compounds responsible for the flavor and aromas that oak imparts into wine. In this article I will consider the sensory aspects of the various oak alternative products, review the ways in which winemakers use these types of products, and why.

For background, I interviewed many winemakers from a variety of winery sizes and locations. The vast majority of winemakers were not permitted by their management to reveal for public discussion that they used any type of oak barrel alternative. As a result, I am not quoting any winemaker specifically, even though it is estimated that about 95% of wineries use these materials in some manner.

This reluctance is unfortunate. Too many in the wine industry fear that if it becomes known that they used oak alternatives in their $50 plus bottle of wine it will be perceived as an inherently lesser wine. Barrel alternative products are like any tool. In the hands of a careful artist, a tool becomes an extension of his implementation of his craft. The more control that the tool allows, the better the artist will be.

I hope readers will take to heart one of the important points from the last article, and extended in this one: the idea that if we as an industry make "green claims" and tout our sustainable production methods, then we must begin a serious evaluation on the environmental impact of oak in winemaking and how the use of oak alternatives impacts that use.

It must be discussed openly and reasonably between the industry and the public, so that consumers become educated about how the use of barrel alternatives both makes good wine and benefits our environment. I regularly give tours at our winery, and when I show visitors the processes and the uses of the many types of barrel alternative products, not only are they fascinated with the process, but instantly grasp the important ways their use can help our environment.

Much of the earlier discussion was based on information gathered by Nadalié. Because of the importance of that information to our discussion here, I will continue that review while focusing on the sensory aspects of the study. This information provides the foundation behind the uses that winemakers are making of the various products. This section of the Nadalié article has 21 graphs that describe the array of differences between the various alternative products.

Sensory perception of oak flavors

In this extended version of the print article published in the June 2009 issue of W&V, there is considerably more graphic data to review. This section is broken down into three subsections based on how the oak's influence on the wine is viewed.

The first group represented by figures 1 to 8 looks at the influence of barrel alternatives from the point of view of each component type over time. The times are four, eight and 12 months. The second grouping is represented by Figures 9 to 14. Here the comparisons are for a fixed aging time of either four, eight or 12 months, for a graphical comparison of a group of products within the time frame. There are two product groups, small pieces and large pieces.

The final grouping (Figures 15 to 20) presents comparisons by flavor component, and includes the final hedonistic graph as a summary. From this series of figures a winemaker should be able to develop a desired methodology to understand how oak alternatives may used in a given wine.

Oak alternatives impart flavors and aromas into wines. They begin with the small pieces called chips and powders; and then move up in size to include dominos, cubes, blocks, inserts and staves. This first series of figures (Figures 1 to 8) shows the impact of various oak alternatives over a period of four to 12 months in the same wine. The Nadalié tasting panel compared these smaller pieces at four months, eight months and then at 12 months.

The panel generally agreed that the extraction of the oak flavors had been completed in four months. Examination of their figure series, however, does not show that to be exactly the case, based upon the intensity scores of the various products. Regardless of the alternative product, they all end up with a score between 5 and 6.

One other common thread indicates that each oak type had certain flavor components that increased in intensity with age, and others that declined. By comparing the variations in the individual components of analysis, one can see differences in the relative concentration of these components. Furthermore, by using different alternative oak products on a wine, the wine's flavor and aroma profiles can be modified by the oak product to suit the wine.

The next six spider graphs shown in Figures 9 thru 14 give sensory analysis information for two representative groups of oak alternative products. Each figure demonstrates the effect of oak extraction over time. Figures 9 and 10 presents the data for two groups of products over four months. Figures 11 and 12 present the same data the same two groups at eight months. Figures 13 and 14 present the effects on the same two groups at 12 months.

Group 1 oak alternative product over time

This first group of figures shows a general trend in which the longer contact times with the oak products presents a greater intensity of the various component aromas and flavors--but that is not completely true for all aroma/flavor components or alternative products. See figure 2--All components are nearly the same from beginning to end. Figure 2 has as many above as below the average in concentration, and the rest are in between these extreme points.

Figure 1 presents medium toast chips and figure 2 heavy toasted chips. Not surprisingly, roasted and smoky character was the primary flavor difference between the standard toast and the heavy toasted chips. In Figure 6, the graph shows the sensory analysis of oak chains at four, eight and 12 months. This series of graphs indicates a discontinuous extraction in the first four months as compared to the subsequent eight months.

Early on, the overall fruit flavor had a more predominant effect on the sensory panel and a somewhat subdued effect on duration and smoky components. As extraction reached its completion at 12 months, the outlier points become more balanced in the wine. This is not surprising, since we know from the Oak-more strategy of flavor extraction (see the April article) that if you want to enhance the overall fruit of a wine, you should not use the first part of an oak extract, as these compounds appear to be more easily released from the oak. The heavier, less volatile compounds of smoke and roast come out later in an extraction regimen.

In comparison, Figure 7 shows an example of the range of difference in the extraction of a product over time, and especially the increase over time of component intensity. Again, referring to both the example of Oak-more and the work of Fine Northern Oak, the compounds that show the most increase in intensity are the higher boiling point compounds.

The exception to this statement about the higher boiling compound extraction happening later in the cycle and the more fruity aromas earlier is the apparent overall fruit impression, shown in Figure 7 as happening at 12 months. This may be due to the increase in complexity of the mixture reaching a more balanced point later in the extraction cycle, with the result that overall fruit appears to increase its presence in the wine.

From my perspective, the most interesting point in the graph in Figure 7 is the flavor duration and overall taste perceptions. I have normally found that duration and overall taste is coupled with intensity and complexity in a wine.

Group 2 oak alternative product at specific time

Figures 9 to 14 compare a range of products at a given time. It was noted before that small piece products supposedly reached their end of extraction early in the cycle, and the larger piece products reach their end after 12 months. However, as indicated earlier that is not strictly true. Notice figure 9: The chips at four months for overall oak are in the middle of smallest products in that group.

Examination of figures 11 and 13 shows the chips increasing their intensity relative to the other components. This suggests it is increasing extraction over time. Figure 13 shows the smaller pieces and Figure 14 the larger pieces at 12 months. These graphs demonstrate the difference in effect of the various products at the completion of their extraction.

As presented in the earlier article, it is quite possible that different manufacturer's production techniques will change the absolute compound distribution, but it is most reasonable to assume that products that are of similar size/surface area will extract at a similar rate for similar types of compounds.

Group 3 flavor/aroma component summary

Group 3 is based on the individual flavor/aroma compounds that comprise oak components in wine. These graphs are wheel graphs that order the alternative product first by approximate size and then by time of extraction. This graphical series shows trends of extraction effect based on the product versus aroma/flavor component. An overall view of this collection should give a good approximation of how each product affects the flavor aroma component.

The graphs shown in Figures 15 and 19 show the comparison of all oak alternative type products for two significant aromas: "overall oak" and "smoky." Four other graphs in this series are "overall fruit (figure 16)," "vanilla/sweet oak (figure 17)," "spicy (figure 20)," and "roasted (figure 18)" components. This series of graphs is the most important aspect of this evaluation process of sensory analysis of oak products. The group of spider graphs shows all the products for all of the extraction periods and the relative evaluation based on the statistical analysis of the entire project.

Depending on your predilection for size of oak component, you can find the size product that justifies your opinion, with the exception of oak chips. Cubes at four and 12 months, blocks at 12 months, barrel inserts at 12 months and Winewood products at eight and 12 months all show very well in overall oak presentation in a wine. Whether you like shorter term or longer term contact, or small versus large pieces, you can find something to use in the way in which you are comfortable.

If this is where it stopped, you could say that the denigration of oak chips could be put to rest--until you look at Figure 21. This bar graph shows how wines made using various oak alternatives were ranked on a purely hedonistic scale. Right up there with all of these other products and ahead of a lot of other large format products is the chipped wine at 12 months.

In my discussions with winemakers across the country and internationally, I have found that more and more of them are using the range of oak alternatives much like the painter's palette. It is obvious that winemakers have available a range of choices in barrel alternatives to use in crafting their wines and imparting the flavors they want into a wine. The problem facing most winemakers is the perennial problem of attention to detail. With all of these tools, there is no reason to have over-oaked wines--unless a winemaker is not paying attention or that is his or her preferred style.

Most winemakers who I have talked with are using oak alternatives in their lesser wines and are trying to extend the life of their existing barrels. Most research shows that barrels do not transmit nearly as much oxygen once the barrels are older than three years.

This would indicate to me that winemakers should be seriously considering some level of micro-oxygenation if that is the direction they are headed. I did not ask about micro-oxygenation during these interviews, and none of them volunteered any indication of their use of that technique.

Many winemakers are adding various forms of oak powders at the crush station, especially in areas where it is cooler or in years where color extraction is expected to be low. The idea behind this practice is that the oak powder will help to fix whatever color comes out as quickly as possible.

Although still a minority, a substantial number of wineries are using exclusively oak alternatives in their wines, from low- to high-end, and of these wineries, several have won significant medals in national and international wine competitions. The careful winemaker should not be afraid of using these products in his whole line of wines.

I anticipate many more advancements on the creation of barrel alternative products and techniques. One example is the Fine Northern Oaks crosscut staves that combine the speed of the extraction of stave-type materials with the advantages of the mass of oak to provide complexity of flavors.

I anticipate that in conjunction with micro-oxygenation in stainless steel and maturation in plastic barrels, the use of oak alternative products is going to become the preferred method of production for most wines. It will certainly take longer for the upper end of the price spectrum to embrace these products and production techniques--until the pioneers of new technology start winning competitions out from under them.

Richard Carey, Ph.D., is president of Vitis Wine Center and winemaker for Tamanend Winery in Lancaster, Pa. He has written numerous articles on new technologies for the grape and wine industry as well as a series of articles on laboratory analyses in Wine East magazine. Please send your comments and questions about this article, as well as ideas for the basis of future articles, to Carey at rcarey@vitisresearch.com.

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Posted on 07.21.2009 - 06:09:10 PST
Disparaging oak barrels under a “Green” umbrella may feel good but ignores the reality of the situation. In my country, Hungary, sound ecological practices go back over 400 years and legal frameworks protecting forests go back 200 years. Forests are harvested in a responsible manner and sustainability is not goal but a reality. Moreover, oak products shipped by ocean freight often have lower carbon footprints than products trucked across America.

As for the role of oak adjuncts, existing “science” and “studies” shine a sliver of light into an otherwise dark room. Experience has shown practicality in some oak adjunct applications but not as a wholesale replacement for oak barrels. As a manufacturer of both oak barrels and adjuncts, we study the adaptations and limitations of our products on an on-going basis. Thankfully, we estimate a fruitful market for oak barrels and adjuncts to be served through a sustainable supply chain.

James Molnar
Managing Director
Trust Cooperage & Quercus LLC
Szigetvar, FL Hungary