Using Grape Pomace as a Additive to Rosé Wines to Improve Wine Quality and Stability

Recycling or reusing grape pomace (a.k.a. grape marc) is a topic that we’ve discussed many times on The Academic Wino. Back in September of last year, I introduced a paper which should that the addition of grape marc to wines prior to bottling may increase the quality of the finished wine by increasing total phenolic content as well as total anthocyanins. Today, I present to you research by the same authors examining the use of grape marc on the quality of Rosé wines (it’s Valentine’s Day, so think pink, right?).

As you’ve heard before if you’ve read any of my previous posts on the subject, grape pomace or grape marc is loaded with antioxidants, polyphenols, flavonoids and stilbenes (think: Resveratrol). Grape pomace has been applied already in many industries, including the health, clothing, construction, and

Photo by davity dave: http://upload.wikimedia.org/wikipedia/commons/thumb/3/33/Pomace_in_the_vineyard_after_pressing.jpg/800px-Pomace_in_the_vineyard_after_pressing.jpg

Photo by davity dave: http://upload.wikimedia.org/wikipedia/commons/thumb/3/33/Pomace_in_the_vineyard_after_pressing.jpg/800px-Pomace_in_the_vineyard_after_pressing.jpg

wine industries (to name just a few). It is important to note, that many of the applications studied have primarily been in research only, and the widespread use of grape pomace in the real world is still well below where it could be.

To examine the effect of grape pomace addition to rose wines, the authors collected grape marc from a local juice processing facility in Spain and further processed it by dehydrating it and then grinding it up into a fine powder. The dehydrated marc (50g/L) was then added to two different white wines: one young white of Airén and one oak barrel fermented white of Airén. Maceration took place over 3 days. In proper scientific methodology, these same wines were tested without the addition of the dehydrated grape marc to serve as controls. The finished rosé wines were then stored for either 1 or 3 months at 18oC, with the following then measured and analyzed: color, phenolic composition, and volatile composition.

Highlighted Results

• At time 0, the color intensity was the same for both grape marc treated and control rosé wines.
• Grape marc treatment wines had increased levels of anthocyanins, gallic acid, (+)-catechin, caffeic acid, (-)-epicatechin, coumaric acid, quercetin, and E-resveratrol.
• Dehydrated grape marc treatment resulted in increased concentrations of linalool (3x higher than its odor threshold), geranyl acetone, and β-ionone, all of which contribute to floral characteristics in rosé wines.
• Compared with control wines, rosé wines treated with dehydrated grape marc showed a reduction in E-nerolidol and isoamyl acetate.
• Compounds contributing to wood aromas, specifically whiskylactones, were not affected by the addition of dehydrated grape marc to rosé wines.
• Volatile compound composition remained stable in treated rosé wines after three months.
• Total polyphenols increased significantly in rosé wines treated with dehydrated grape marc compared with controls (5x greater, actually).
• Color in the rosé wines treated with dehydrated grape marc remained stable over the three month period.
o This preservation was attributed to the increase levels of antioxidants in the treated wines, thus resulting in the stabilization of anthocyanin content over time.

Conclusions

The results of this study showed, according to the authors, that dehydrated grape marc may have great potential for being used as an additive in wines. Particularly, adding dehydrated grape marc during the rosé winemaking process could help stabilize the color of rosé as it ages (at least through 3 months…) and also significantly increase the beneficial antioxidants and polyphenols present in the finished wine. According to the author, the increase in antioxidants as a result of the added dehydrated grape marc could lead to protection against early oxidation in rosé wines.

Overall, I think this study has very interesting and significant applications to winemaking. Using dehydrated grape marc in wine production (particularly rosé wine production) could improve color stability over time as well as improve the aromatic profile of the finished wine. Additionally, adding grape marc to wines

Photo by Designovum http://farm5.staticflickr.com/4031/4706139681_c9894d1b97.jpg

Photo by Designovum http://farm5.staticflickr.com/4031/4706139681_c9894d1b97.jpg

could significantly improve the overall “healthiness” of the wine by increasing the health-beneficial polyphenols and antioxidant compounds. However, one thing I would like to see is a sensory analysis of these wines that have been treated with dehydrated grape marc, to ensure that the compounds found in the wines are reflected in the aromatic and sensory characteristics of the finished wine.

I’d love to hear what you all think of this study and this topic. Please feel free to leave your comments!

Source: Pedroza, M.A., Carmona, M., Salinas, M.R., and Zalacain, A. 2011. Use of Dehydrated Waste Grape Skins as a Natural Additive for Producing Rose Wines: Study of Extraction Conditions and Evolution. Journal of Agricultural and Food Chemistry 59: 10976-10986.

6 comments for “Using Grape Pomace as a Additive to Rosé Wines to Improve Wine Quality and Stability

  1. WineKnurd
    February 16, 2013 at 11:03 am

    Burgundy has had a terrible time lately with “premox”, or premature oxidation of thier white wines. I wonder if a white DGM treatment might help to prevent such premox from happening?

    The ultimate question of course is, how do these wines taste after DGM treatment? Did the authors of the study not taste the wines? It says they were stored at 65˚F, cool enough for a swirl and taste experiment.

    Also, I am copyrighting “DGM treatment” to stand for dehydrated grape marc treatment. wDGM and rDGM for white and red marc respectively. It sounds cool and scientific and I think it will catch on :)

    • Becca
      February 16, 2013 at 9:47 pm

      That’s one thing I was hoping for that the authors did not do–a “taste test”. The chemistry is certainly telling, but you can’t be certain without actually tasting the wine :)

      The authors actually used the term “DWGS” for dehydrated waste grape skin, which is pretty similar to your DGM moniker. :) I’ll let you all fight over which is cooler ;)

  2. WineKnurd
    February 17, 2013 at 11:26 am

    Becca, I just realized something didn’t quite make sense here, but it was clarified after I was able to read the abstract of the article. The authors are suggesting the use of DWGS as a method for the production of rose wines, as an additive to white wines. My criticism is that rose wines are made from the (white) juice of red grapes and not by rDWGS added to a fully fermented white wine. A proper control in this case would be using the white juice from the red grape variety and macerating DWGS of this red grape, compared to a rose wine made as normal from this same grape (e.g., a traditional rose of Temperanillo compares to Temp. DWGS allowed to macerate in white Temp. juice).

    The abstract also suggests this might be a cheap alternative in the production of rose wines using a white grape, but I do not see any economic advantage to this other than the recycling of grape marc. White zin is currently made by allowing the zin juice to have brief contact with the skins and sells for peanuts.

    Can’t believe I am refuting a scientific paper by invoking white zinfandel…

    • Becca
      February 17, 2013 at 11:35 am

      It sounded to me that the economic advantage was for the recycling part, in that they didn’t have to do too much to the stuff to be able to reuse it.

      I think they could have still used the control that they did use, but they were certainly lacking the second control like the one you mentioned in your comment.

      Also, there are a lot of people who love White Zin, so they probably figured that this isn’t going to change anytime soon and the producers of those wines might want to take advantage of this technique at the very least for recycling/environmental purposes!

  3. WineKnurd
    February 17, 2013 at 1:19 pm

    Brings up an interesting question though, can a wine be labeled “rose” if the base juice is from a white grape?

    • Becca
      February 17, 2013 at 1:43 pm

      If you ask wikipedia it can be ;)

Comments are closed.