Tag Archives: tempranillo

Partially Fermenting Sun-Dried Tempranillo Grapes Produce a Sweet Wine with Greater Complexity than Traditional Approaches

Posted on December 17, 2012 by Becca| Leave a comment

 

Sweet wines, or what many in America refer to as “dessert wines” even though they pair well with more than just dessert, are made in many different styles and in many corners of the world.  From Canadian ice wine to French Sauternes, these wines are created by employing more complex methods prior to and sometimes during fermentation that make them stand out and differ from your typical red or white table wine.  Of course, there are some less-than-quality ways of making sweet wine, which simply involve adding sugar back to the wine after

By seligmanwaite [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

By seligmanwaite [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

fermentation is complete, however, for the purpose of today’s post, we are only talking about high quality sweet wines, the sweetness by which is a function of the natural sugar in the grapes/wine rather than added after the fact.

For nearly all sweet wines, sugar levels inside the grape are much higher than typical red or white grapes destined for table wines, which occurs by several different mechanisms.  For Sauterne wines from France and Tokay wines from Hungary, the grapes are left to be infected by the fungus Botrytis cinerea, which while in these sweet dessert wines is preferred, it is actively combated against for table wines.  Other sweet wines are created by allowing grapes to remain on the vine for a lengthened period of time or by dehydrating them in the open air.  Finally, ice wines (eiswein) are created by freezing the grapes, which effectively freeze the water inside the grape but not the sugar, so that the only thing that gets pressed out of the grape is juice that is highly concentrated in sugar.

When grapes undergo the dehydration process, they are often laid out onto mesh mats (or something similar) and allowed to dry for 7 to 10 days, or however long it takes to reach around or higher than 45oBrix (450g/L sugar).

This increased level of sugar in the grapes can be problematic during the fermentation process, as many yeasts are not equip to function in high concentrations of sugar, resulting in incomplete or stuck fermentations or other fermentation problems.  To combat this problem, some regions (particularly the Montilla-Moriles region of Spain) practice a fortification method, by adding 8% v/v ethanol to the must in order to achieve the appropriate levels of alcohol in the wine without having to undergo fermentation.

In these situations where ethanol is added to kill the yeasts and avoid fermentation all together, the wine takes on the characteristics of the grapes themselves.  However, with fermented wines, the wine takes on the characteristics not only of the grapes, but also of the interaction of the grapes and the yeasts, adding more complexity to the wine than if it remained unfermented and fortified with ethanol.  Wines that are made from dried grapes that don’t undergo fermentation also sometimes have problems with appropriate acid levels in order to achieve a satisfactory acid-sugar balance in the finished wine.

Photo credit: I, Tomas er [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or FAL], via Wikimedia Commons

Photo credit: I, Tomas er [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or FAL], via Wikimedia Commons

In order to solve the fermentation problems that are created when using dried grapes with high levels of sugar, the study presented today aimed to examine the fermentation of the musts made from these grapes using yeasts that are capable of withstanding the high sugar levels and to determine the contribution of these yeasts to the volatile and aromatic composition of the finished wines.  Today’s study also aimed to determine if using these “specialized yeasts” create higher quality wines than wines created from the traditional fortification methods.

Methods

The grapes used in this experiment were Tempranillo from the Montilla-Moriles region of Spain.  Grapes were harvested around 25oBrix (250g/L) and sun dried until the grapes reached about 45oBrix (450g/L).  After pressing, must was split into 8 different batches of 1.5L each for treatment.

Treatments:

  • The first two batches were treated with Saccharomyces cerevisiae yeast of the strain CECT 13014.
  • The second two batches were treated with S. cerevisiae yeast of the strain CECT 13015.
    • Both of these S. cerevisiae yeast strains are known to be tolerant of high sugar levels during fermentation.
  • The next two batches were treated with native yeasts that are known to undergo spontaneous fermentations.
  • The last two batches were treated using the traditional approach of fortification with 12% v/v ethanol.

Partial fermentation took place in 2L flasks at 22oC until alcohol levels in each treatment was 8 % v/v.  Once this alcohol level was achieved, all fermentations were stopped by adding 12% v/v of ethanol.

Volatile compounds were measured in all treatments using GC-MS.  Odor activity values (OAVs) of these compounds were also calculated (a value over 1 indicates it contributes to the aroma of the wine)

Sensory analysis of each wine was performed by a panel of 15 “expert tasters”.  There were no other details given in the paper in regards to how the analysis was performed, and what qualified the panelists “expert tasters”.

Results

  • The most influential volatile compounds in the traditional wine (i.e. wine fortified with ethanol and no fermentation) were:
    • Acetoin, 2,3-butanedione, pantolactone, guaiacol, acetaldehyde, ethyl acetate, and 4-valerolactone.
  • The most influential volatile compounds in wines treated with natural yeasts were:
    • Guaiacol, butyrolactone, and pantolactone.
  • The most influential volatile compounds in wines treated with S. cerevisiae strain CECT 13014 were:
    • Acetoin, 2-phenylethanol, propanoic acid, ethyl hexanoate, isoamyl acetate, acetaldehyde, ethyl acetate, and 4-valerolactone.
  • The most influential volatile compounds in wines treated with S. cerevisiae strain CECT 13015 were:
    • Propanoic acid, 2-phenylethanol, ethyl hexanoate, butryolactone, and 4-valerolactone.
  • The aromas of chemical, ripe fruit, milky, and toast were present in all wines.
    • Those wines partially fermented with S. cerevisiae strains were higher in these aromas, in addition to green fruit aromas, than the other wines.
    • Milky aromas were lower in traditionally made wines.
  • Wines made from the two strains of S. cerevisiae were very similar to one another.
    • Wines made from native yeasts were similar to wines made from S. cerevisiae treated wines.
    • Traditionally made wines (i.e. fortified with ethanol and no fermentation) were very different from the wines treated with yeasts and that underwent partial fermentation.

Sensory Analysis

  • Sensory analysis indicated that the traditionally made wines scored worse than all other wines.
    • The order of acceptance of the four wines was the following:
      • Traditional Wines < Wines treated with native yeasts < Wines treated with S. cerevisiae strain CECT 13015 < Wines treated with S. cerevisiae strain CECT 13014.
  • The highest scoring wine in the sensory analysis was the wine treated with S. cerevisiae strain CECT 13014.
    • This was the only wine deemed “desirable”, while all other wines were deemed “acceptable”.

Conclusions

The results of this study showed that by partially fermenting sun-dried Tempranillo grapes with S. cerevisiae strains that have the ability to function under high sugar levels during fermentation, finished wines were more complex and more desirable in terms of sensory characteristics than wines made in the traditional fashion.  As a result of these findings, the researchers claimed that partially fermenting sun-dried Tempranillo grapes with the appropriate strain of yeast is an effective alternative to the traditional approach.

Overall, this was a straightforward study that provided interesting and potentially useful and applicable results for the wine industry.  I would have

By Ludo (originally posted to Flickr as Marsala.secco.) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

By Ludo (originally posted to Flickr as Marsala.secco.) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

liked to have seen the experiment carried out in larger vessels, particularly vessels that are similar to those tanks and barrels used it the wine industry, instead of using small 2 liter flasks.  It’s possible that increasing the volume could change the outcome, though I wouldn’t be surprised if we saw the same results in the larger vessels as well did with the small.

I would love to hear what you all think about this study. Please feel free to leave you comments!

Source: López de Lerma, N., García Martínez, T., Moreno, J., Mauricio, J., and Peinado, R. 2012. Sweet wines with great aromatic complexity obtained by partial fermentation of must from Tempranillo dried grapes. European Food Research and Technology 234: 695-701.

Posted in Enology

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Altering the Aromatic Profile of Tempranillo Wines Using Foliar Urea Fertilization

Posted on December 10, 2012 by Becca| 5 Comments

 

The use of soil nitrogen fertilization has been frequently studied in grapes for its ability to alter wine aroma, however, the results of these studies have been quite variable.  Some studies found that using organic and inorganic nitrogen fertilization improves wine aroma by increasing the concentrations of desirable aromatic volatile compounds, while many others found that this application damages wine aroma by increasing the levels of urea and ethyl carbamate, both of which are undesirable in wine.

One problem with using soil nitrogen fertilization is that the nitrate salts in the fertilizer are extremely soluble, thus increasing the risk of the salt leaching (i.e. leaking) into the soil and not contributing at all to fertilization or wine aroma.

U.S. National Archives and Records Administration: Photo in Public Domain

Also, the more that this salt that leaks out into the soil, the greater the risk is of environmental harm and degradation.

In addition to soil fertilization, some vineyard managers opt to incorporate foliar fertilization (i.e. fertilization applied to the leaves), which functions as a more direct way to get nutrients to the vines instead of having much of it leach out into the soil unused.  Since foliar fertilization results in the direct absorbance into the grapes themselves, much less of it needs to be applied than soil fertilizer.

With the knowledge that fertilization of grape vines affects wine aroma by increase the levels of certain desirable volatile compounds, one study aimed to examine the effects of foliar fertilization of urea (a nitrogen-based compound) on Tempranillo grape vines and how this fertilization altered the volatile chemistry of the finished wine.  According to the authors, this type of study has never been done on Tempranillo vines.

Methods

Tempranillo vines (Vitis vinifera) from the 2008 vintage were used in this study.   Experimental vines were split into three plots in the same vineyard which was located in the Rioja region of northern Spain.  The vines were planted in 1990, and were about 9 ha total in vineyard size.  Vine density was 2.7m x 1.5m, and the pruning regime used was the Gobelet method.

Soil pH was 8.3 and nitrogen fertilizer was applied to the entire vineyard at 21kg N/ha.

Two of the experimental plots were foliar urea fertilizer treatment plots, with one plot receiving 2kg N/ha and the other receiving 4kg N/ha.  The third experimental plot was left untreated as a control.

Foliar fertilizer used was Nitrotecnia-20, 20% w/w of the total nitrogen in the fertilizer originating from urea.

Foliar urea fertilizer was applied at 7 day intervals between July 31st and October 9th, 2008.  Treatment was started close to veraison (i.e. when the grapes start to change color) in order for the urea to be absorbed directly by the grape instead of most of it going into the leaves of the plant.  As a side note for

By Véronique PAGNIER (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

those that aren’t very familiar with veraison, at this stage of a grape’s life, the skin becomes more permeable, allowing more “stuff” to be absorbed than prior to this stage when the skin was tougher and not letting as much inside.

At harvest, all grapes from all three plots were harvested, in order to create a homogenous must/wine from each plot.  Grapes were de-stemmed, crushed, and pressed.  The common wine yeast, Saccharomyces cerevisiae strain MV 92081 was used for the fermentation.  Fermentation was held in stainless steel tanks and wine was fermented until dry.  Wines were subsequently stabilized the filtered. Fermentation occurred in duplicate.  Wine samples for analysis were chosen from different parts of the tank then blended, in order to create representative samples of the entire batch.

Odor activity values (OAV’s) were calculated for each volatile compound.  Any OAV’s over a value of 1 meant that the flavor threshold has been reached meaning that the aroma of that compound can be detected in the wine.

In addition to measuring volatile compounds, amino acids, ammonium nitrogen, yeast assimilable nitrogen, and general enological parameters were measured.

For sensory analysis, 5 panelists (3 men and 2 women) were selected from 5 different wineries in Rioja.  Panelist judged body, acidity, sweetness, bitterness, astringency, and tannin, as well as red fruits, plums, currants, chocolate, honey, vanilla, and green.  Each characteristic was judged using a 5 point scale: 1 = very poor; 2 = poor; 3 = acceptable; 4 = good; and 5 = very good.  Six sets of 3 wines were used for forced-choice tests.

Results

  • Total acidity was higher in musts made from grapes treated with urea than musts made from control grapes.
  • pH increased in the musts and wines of grapes treated with urea.
  • Alcohol content (including higher alcohols) and total acidity decreased in wines made from grapes treated with urea compared with wines made from control grapes.
  • Volatile acidity was below threshold for all wines.
  • Amino nitrogen and YAN levels increased in wines made from grapes treated with urea.
  • Isoamyl alcohol, isobutanol, 2-phenylethanol, tyrosol, tryptophol, and 3-methylthio-1-propanol all decreased in wines made from grapes treated with urea compared to wines made from control grapes.
    • 1-hexanol and benzyl alcohol did not change due to treatment.
    • 1-butanol increased in wines made from grapes treated with the higher dose of urea.
    • OAV levels of isoamyl were greater than 1 in all three wines, thus corresponded to aroma.
    • OAV levels of 2-phenylethanol were greater than 1 in control wines and the lower dose of urea wines.  (This compound contributes to floral characteristics in wine).
    • OAV levels of 2-phenylethanol were lower than 1 in the higher dose of urea wines, thus it did not contribute to the aroma of those wines.
  • Precursor amino acids (with the exception of the precursor to tryptophan) all increased in wines made from grapes treated with urea compared with the control.
  • Total esters decreased in wines made from grapes treated with urea.
  • Ethyl hexanoate, ethyl octanoate, and ethyl decanoate all increased in wine made from grapes treated with the higher dose of urea.
    • Ethyl hexanoate and ethyl octanoate OAV levels were greater than 1 for all wines, thus they both contributed to the aromatic profile of the wines, though the levels were significantly higher in the wines made from grapes treated with the higher dose of urea.
  • Isoamyl acetate and ethyl acetate levels decreased in wines made from urea-treated grapes and contributed to wine aroma.
  • Diethyl succinate, diethyl malate, and ethyl-3-hydroxybutyrate decreased in wines made from urea-treated grapes.
  • 3-hydroxy-2-butanone and acevanillone increased in wines made from the grapes treated with the highest dose of urea.
  • Foliar urea fertilization did not have much of an effect on fatty acids in wines.
    • Butyric acids increased with grapes treated with the highest dose of urea.
    • C10, C12, C14, C16, and C18 fatty acids (i.e. fatty acids with 10, 12, 14, 16, and 18 carbons) decreased in wines made from grapes treated with urea.
  • Sensory Analysis:
    • Body, acidity, sweetness, bitterness, and tannin were similar for all three wines.
    • Wines treated with foliar urea fertilizer were lower in astringency than control wines.
    • Fruity notes were higher in wines made from urea-treated grapes.
    • Notes of chocolate, honey, and vanilla were the same for all three wines.
    • Herbaceous notes were higher in control wines than wines made from urea-treated grapes.
    • Wines made from urea-treated grapes were noted to have higher aromatic intensity, fruitier character, and bigger red fruit notes than control wines.
    • Isoamyl alcohol and 2-phenylethanol are compounds than tend to cover up wine aroma, and it was found that wines made from urea-treated grapes were lower in these compounds than control wines.

Conclusions

The results of this study showed that there are significant differences in the aromatic profile of wines made from grapes that were treated with foliar urea fertilization.  It is not known whether the panelists preferred one type of wine over another, just that the aromatic profiles were different.  For Tempranillo wines made from grapes treated with foliar urea fertilization during the growing season, the aromatic profile shows increased fruity notes, as well as greater aromatic intensity.  For control Tempranillo wines not treated with any foliar fertilizer, aromatic intensity was lower, and herbaceous notes were more pronounced.

It doesn’t appear that one wine was necessarily better than the other, but then again, there were no questions in the sensory analysis that addressed this question.  Depending on what style of wine you enjoy, you may like either the

By María Jesús Tomé (Flickr: Rioja Alavesa) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

control wines or the wines treated with foliar urea fertilization.  The authors of this study claimed that urea treatment did, in fact, improve the aromatic profile of Tempranillo wines.

If you want to create a Tempranillo wine that is fruitier and more aromatic, it may be beneficial to employ a foliar urea fertilization regime in your vineyard management practices.  It would be important to know how this fertilization treatment affects not only the grapevines and the resulting wine, but also the environment around it.  This may be something to consider prior to employing such a practice.

It’s not clear how this type of treatment would affect other grape varieties; however, one would likely expect to see a varied outcome.  Certainly, some grapes would have the ability to absorb more of the fertilizer than others, and some grapes would be able to utilize the excess nitrogen better than others.  The effect of foliar urea fertilization is likely a case-by-case situation and it would be interesting to see in a follow up study how other grapes and resulting wines were affected by the treatment.

I’d love to hear what you think about this study. What other questions would you have liked to see answered that the authors did not discuss?  Please leave your comments!

Source: Ancín-Azpilicueta, C., Nieto-Rojo, R., and Gómez-Cordón, J. 2012. Effect of foliar urea fertilization on volatile compounds in Tempranillo wines. Journal of the Science of Food and Agriculture. Released online prior to publication in print. DOI 10.1002/jsfa.5921.

Posted in Viticulture

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Who’s Your Daddy?: Tempranillo

Posted on September 28, 2012 by Becca| 10 Comments

The “Who’s Your Daddy” series takes a brief look at the parentage of grapes, in order to get a better understanding of where particular varietals come from and how they are genetically related to one another.  So far, we’ve covered: Cabernet Sauvignon, Syrah, Chardonnay, Petit Verdot, Sangiovese, Nebbiolo, Pinotage, Gamay, Petite Sirah, and Merlot.  Feel free to click on any one of the varietal names to read all about their parentage.

http://i.images.cdn.fotopedia.com/flickr-2559447601-hd/Tokyo_and_Vicinity/Places_of_Interest/Museums__Galleries/Miraikan/DNA.jpg

The subject of today’s “Who’s Your Daddy” post is Tempranillo, a grape that for some reason always makes me roll my r’s a little bit longer than I probably should!

History

The name “Tempranillo” is well accepted to be derived from the word “temprano”, meaning early, which is likely related to the early ripening of the grape.  The word “Tempranillo” was recorded only sporatically through its early history, but it’s thought that the grape has been around at least since the 13th century and perhaps earlier.  Tempranillo hails originally from Spain, and has been the predominant grape in wines from both Rioja and Ribera del Duero.  In fact, Tempranillo is mostly grown in Spain, though you will find Tempranillo vineyards in other small corners of the world, including the United States, South America, South Africa, New Zealand, Australia, Argentina, and a few others.

After spending potentially hundreds of years in Spain, the grape may made its way to (*Edit: South) America some time during the 17th century by the Spanish Conquistadors.  More than likely, the Conquistadors brought the vines over by seed, which allowed the grape to slowly establish itself in places that were more hospitable to the conditions needed for optimal growth.  Tempranillo finally reached the west coast of the United States by the early 1900s, though it took some time for it to popularize and establish due to its “disagreement” with the growing conditions of the area and its desired viticultural requirements.

Viticulture

For ideal ripening and development, Tempranillo vines prefer hot days and cool nights, a combination that is not found in every viticultural growing area.  *Edit: A great comment left by Earl at the end of this post reminded me that another very important characteristic of Tempranillo viticulture is that it has a short growing season.

Tempranillo does best in calcareous clay soils, though also does well in soils rich in iron, chalk, and limestone.  As with many grapes, sloping terrain is beneficial for drainage, and it tends to do well at higher altitudes.

Tempranillo is prone to attack by a variety of pests and diseases, since it does not have immunity to any sort of ailment.  Though the thick dark skin provides some protection again disease, the very tight cluster formation is very attractive for critters than want to set up camp and go to town on the grapes and grapevines.

Sensory Characteristics

Tempranillo is often used in blends (think Rioja, etc), though is thought to be the solid backbone of these blends to provide color and unique flavor contributions to the finished wine.  Anthocyanin levels in Tempranillo grapes are very high, which explain the deep red color of the wine.

In younger Tempranillo wines, the grapes of which were grown in cooler climates, the aromatic profile tends to consist of red fruit flavors, including strawberries, black currants, and cherries.  On the other hand, in older wines, the grapes of which were grown in hotter climates, the aromatic profile is reminiscent of prunes, chocolate, and tobacco.  Tempranillo also often has a characteristic “earthy minerality” to its flavor profile.

In regards to structure, Tempranillo wines tend to be low in acidity, with moderate to high levels of tannin and moderate levels of alcohol.  As a result of these characteristics, Tempranillo has a generally smooth mouthfeel, as well as rich aromas and flavors.  Finally, Tempranillo is known to do very well in oak, as the vanilla and coconut characteristics of the oak complement the fruit and minerality components of the Tempranillo wine very well.

So, Tempranillo….”Who’s your daddy?”…

We know where Tempranillo came from originally, however, which grapes gave rise to the Tempranillo grape to begin with?

Researchers at the CSIC Universidad de La Rioja, Gobierno de La Rioja and the Instituto Madrileño de Investigación y Desarrollo Rural, Agrario y Alimentario (IMIDRA) recently uncovered the genetic origins of Tempranillo by genotyping analysis for SNP and microsatellite markers in grapevine germplasm collections and published their work just one month ago in the American Journal of Enology and Viticulture.

Without further ado, I present to you the genetic parents of Tempranillo:

Albillo Mayor…..

http://img.interempresas.net/fotos/749483.jpeg

 

 

 

…and…

 

 

 

Tempranillo grapes: http://www.wineaccess.com/graphics/grapeimages/tempranillo.jpg

 

 

…..Benedicto!

 

 

 

 

 

Neither of these grapes is particularly well known in the United States, though Albillo Mayor is still well-established in the Iberian Peninsula of Spain.  Benedicto, on the other hand, is rarely cultivated today and is not very well known even in the historical record.

There you have it!  If you’d like to learn about the parentage of another grape variety, simply leave a comment below and I’ll see what I can dig up!  Note: there are many grape varieties with unknown parentage still, but I’ll try my best to find data that may suggest particular relationships and origins.  This type of genetic research is ongoing, so even if I can’t find information on a particular grape of your choosing today, that may change in the future!

Cheers!

(Citation for the genetics research article: Ibáñez, J., Muñoz-Organero, G., Zinelabidine, L.H., de Andrés, M.T., Cabello, F., and Martínez-Zapater, J.M. 2012. Genetic origin of the grapevine cultivar Tempranillo. American Journal of Enology and Viticulture. ajev.2012.12012 published ahead of print August 17, 2012.)

(Source for article citing possible introduction of Tempranillo seeds to South America: http://www.ejbiotechnology.info/content/vol6/issue3/full/11/index.html)

 

Posted in Genetics

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