Tag Archives: winemaking

Comparing Biogenic Amines and Polyphenols of Grapes and Wine After Conventional, Biodynamic, and Organic Practices: Which Method is Best?

Posted on April 15, 2013 by Becca| 4 Comments

 

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Welcome to The Academic Wino! If you are new here, please read the “About Me” page to find out more about myself and the blog. If you would like to receive free updates on articles like this by email, then sign up here or you can subscribe to the RSS feed. Also, check us out on Twitter, Facebook, Google+, and or Pinterest. Thanks for visiting!

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Biogenic amines are carefully monitored in the food and beverage industries, since if they are taken in at too high of concentrations, they can cause significant health problems including headaches, breathing problems, and cardiac problems. Biogenic amines are nitrogen-based compounds that are derived from amino acids and include compounds such as histamine, serotonine, tyramine, tryptamine, phenylalanine, agmatine, putrescine, cadaverine, spermidine, and spermine. Many of these compounds may be formed during the fermentation processes of food and beverage production, which are caused by interactions with the microbial population in the system.

In wine, several biogenic amines have been identified, with the most common being histamine, tyramine, and putrescine, and with concentrations reported up to 50mg/L. It has been shown that polyphenols in wine actually serve to keep biogenic amine levels in check, as some polyphenols in wine have been seen targeting the enzymes facilitating biogenic amine production, thus keeping amine levels relatively low. In essence, these polyphenols are providing protection to the wine so that these biogenic amine compounds don’t rise to potentially toxic levels.

Several studies have examined whether or not certain agricultural or processing techniques affect the balance of polyphenols and biogenic amines in a variety of food products with varied results. Studies have examined conventional, organic, and biodynamic agricultural methods only to come up short in terms of general

Photo By drdcuddy (Flickr: Italia 2010) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

Photo By drdcuddy (Flickr: Italia 2010) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

observable trends. Some studies have shown that organic products have better biological activity than conventional products, while other studies have found no differences between conventional and organic agriculture and production methods. In general, it is assumed that organic and biodynamic agriculture and production methods are better for human health overall, though there is no solid scientific evidence to back that up quite yet (only mixed results).

Generally speaking, organic agriculture and biodynamic agriculture are very similar in that they both utilize composting and cover crops and prohibit the use of commercial pesticides, fungicides, herbicides, and other sorts of man-made chemicals. One major difference between the two practices is that biodynamic agriculture utilizes special preparations that use mineral and/or herbs, as well as various animal organs, which can be buried until the soil or made into a spray to apply to the foliage of the plants.

The study presented today aimed to compare conventional, organic, and biodynamic viticulture and winemaking practices for both red and white grapes and wine, and to determine if any of these methods differ from one another in terms of their polyphenol and biogenic amine content and particularly if one viticulture or winemaking method is ideal compared to the rest in terms of wine and human health quality.

Methods

Red and white grapes of the Sangiovese and Pignoletto varieties, respectively, were all grown in 2009 from vineyards in the Emilia-Romagna region of Italy. Conventional, organic, and biodynamic viticulture practices were performed for the different treatments.

Grapes were all picked on the same day from random locations throughout the vineyards and throughout the vines and clusters. 10kg of grapes were harvested from each treatment vineyard and were ground into a powder for chemical analysis.

Wine was made from the grapes at each of the treatment vineyards on site using conventional, organic, and biodynamic winemaking practices.

The following biogenic amines were measured for both grapes and wine: tryptamine, histamine, tyramine, diamine-propane, cadaverine, putrescine, spermidine, and spermine.

The following were measured for both grapes and wine: total polyphenols, individual polyphenols, anthocyanins, and antioxidant activity.

Results

Grapes

• Putrescine was the most abundant biogenic amine in all samples.
• Tryptamine was 4.7 times higher in Sangiovese grapes than Pignoletto grapes.
• Total biogenic amine levels in Sangiovese grapes were 5.5 times higher than in Pignoletto grapes.
• There were no clear trends or differences between viticulture methods in terms of biogenic amine levels.
• There were no significant differences between viticulture methods in terms of total polyphenol levels.
• Total anthocyanins were significantly higher in Sangiovese grapes compared with Pignoletto grapes (as expected).
• Total anthocyanin levels were highest using conventional viticulture methods, followed by biodynamic methods and finally organic methods.
• Catechins and stilbenes were significantly different between the Sangiovese and Pignoletto grape varieties (lower in Pignoletto grapes); however there were no significant differences between the two groups in regards to viticulture practice treatment.
• Resveratrol and trans-resveratrol were found in all samples, though cis-piceid and trans-resveratroloside were only found in Sangiovese grapes.
• Piceatannol was 2 times higher in Pignoletto grapes compared to Sangiovese grapes.
• Sangiovese grapes had 3 times greater antioxidant capacity than Pignoletto grapes.

Wine

• Biogenic amines were 3.6 times higher in Pignoletto wines compared with Sangiovese wines.
• There were no differences in biogenic amine levels between the different winemaking practices.
• Total polyphenols were 6.5 times higher in Sangiovese wines compared with Pignoletto wines.
• Sangiovese wines had the highest levels of anthocyanins and stilbenes compared with Pignoletto wines.
• Sangiovese wines had greater antioxidant capacities than Pignoletto wines.

Conclusions

The results of this study indicated that there were no significant differences in the chemical profile of Sangiovese and Pignoletto wines when treated with conventional, organic, or biodynamic viticulture and winemaking practices. The clear differences found in this study were in terms of grape variety (red versus white), and not viticulture or winemaking method, which was confirmed using Principle Components Analysis. Sangiovese grapes were found to have higher levels of biogenic amines, though none of the levels were high enough to cause a threat to human health. Conversely, after the winemaking process, it was found that Pignoletto wine had higher levels of biogenic amines compared with Sangiovese, which is likely due to winemaking technique and the interactions with the compounds present in the white must.

It seems as though reducing the levels of biogenic amines in wines may be difficult, as there are a number of factors that could be contributing to their

Biodynamic Composting. Photo credit: By Mark Smith [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

Biodynamic Composting. Photo credit: By Mark Smith [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

levels (i.e. grape variety, winemaking technique, geographical growing area, etc), though this study shows that using biodynamic or organic viticulture or winemaking methods as opposed to conventional methods will not affect biogenic amine levels.

Of course, there are many environmental benefits of using biodynamic and organic viticulture and winemaking practices, so these results are certainly not meant to deter anyone from adopting these methods. It’s simply a matter of determining what viticulture or winemaking technique will help lower biogenic amine levels in wine, and it’s clear from the results that choosing biodynamic or organic methods over conventional methods will not help in this case. I encourage biodynamic and organic agriculture and production methods, though again if one is seeking to change practices just to lower biogenic amine levels, switching to either of these won’t make a difference (but it will make a difference in other areas!).

I’d love to hear what you all think of this topic! Feel free to share comments or stories with everyone!

Source: Tassoni, A., Tango, N., and Ferri, M. 2013. Comparison of biogenic amines and polyphenol profiles of grape berries and wines obtained following conventional, organic and biodynamic agricultural and oenological practices. Food Chemistry 139: 405-413.

Posted in Chemistry, Environmental Science

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Book Review: American Wine – The Ultimate Companion to the Wines and Wineries of the United States by Jancis Robinson and Linda Murphy

Posted on April 12, 2013 by Becca| Leave a comment

 

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Welcome to The Academic Wino! If you are new here, please read the “About Me” page to find out more about myself and the blog. If you would like to receive free updates on articles like this by email, then sign up here or you can subscribe to the RSS feed. Also, check us out on Twitter, Facebook, Google+, and or Pinterest. Thanks for visiting!

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I was very excited to crack open American Wine: The Ultimate Companion to the Wines and Wineries of the United States by Jancis Robinson and Linda Murphy, and I have to say that I was not disappointed!

To purchase American Wine: The Ultimate Companion to the Wines and Wineries of the United States by Jancis Robinson and Linda Murphy, click here to be taken to Amazon.com.

American Wine: The Ultimate Companion to the Wines and Wineries of the United States presents a wonderful history of wine in the United States, as well as how viticulture and enology have evolved in this country and how vineyards American_Wine_The_Academic_Winoand wineries continue to grow and change in an ever fluid market. Perusing through the pages, I could tell that a lot of time, energy, and research was put into the making of this book, and made me appreciate it that much more.

American Wine: The Ultimate Companion to the Wines and Wineries of the United States is basically divided up by general region of the United States (i.e. West, Southwest, Midwest, Southeast, and Northeast), subdivided by state, and then even further divided by individual American Viticulture Area (AVA). Having put together large-scale reviews during my Masters work, I can appreciate the organization and research that was required to go into creating a manuscript such as this book. There are 278 relatively large pages with small font chock full of very interesting histories and current practices for each of the many AVAs throughout the country.

American Wine: The Ultimate Companion to the Wines and Wineries of the United States, while full of fascinating information on viticulture and winemaking in the United States, also has a wonderful selection of images gracing nearly every page, highlighting much of the beauty and wonder of the many wineries throughout this country. Coupling the images with the text, the book comes together very nicely and makes an amazing gift for the wine lover in your life.

One of the great things about this book is that you don’t have to read it from cover to cover in any particular order. Skip around! Read what area of the country interests you most that day. Maybe you’re trying a wine from an area in the United States that you haven’t tried before—this book would be a wonderful companion to your wine education in regards to learning about the history and current practices of that particular area that interests you.

Seeing as how I live in Virginia, of course I made my way over to the Virginia wine section of the book relatively quickly. I felt the book captured the Virginia wine scene very well, and didn’t leave me scratching my head wondering why something was included or omitted. I was pleased to see some of my favorite wineries highlighted as “steady hands” in the Virginia wine industry, meaning that they are consistently great quality and are some of the leaders in the area (shout out specifically to Afton Mountain Vineyards, Jefferson Vineyards, King Family Vineyards, and Veritas Vineyards who were all mentioned in that section of the book!).

I highly recommend this book to anyone who enjoys reading about wine and wine history. It’s also a great resource if you’re looking for current players in the field, and if you’re curious about the up-and-coming vineyards and wineries in the United States. This book is a great value and is certainly one that I will be proudly displaying on my coffee table for the foreseeable future.

To purchase American Wine: The Ultimate Companion to the Wines and Wineries of the United States by Jancis Robinson and Linda Murphy, click here to be taken to Amazon.com.

Posted in Literature

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Using Carrageenan or Pectin as Possible Alternatives to Bentonite for Protein Removal in White Wines

Posted on April 10, 2013 by Becca| 4 Comments

 

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One very important step in the white winemaking process is the removal of proteins that cause a hazy appearance of the wine while in storage. Often, bentonite is used to remove these proteins, as the negatively charge bentonite will attract the positively charged proteins and settle out to the bottom of the tanks where they can be left behind. Though the use of bentonite is efficient in removing proteins from white wine, some claim it has less than desirable side effects, including the loss of wine since it can’t be reused, as well as the cost of its disposal and potential changes in the aromatic profile of the finished wine. Some studies have shown no effect on aromatics by bentonite, while others have shown it does negatively affect the aroma. As a result, finding an alternative to bentonite for removing proteins from white wines may be important.

Two possible alternatives to bentonite that are the focus of the study presented today are carrageenan and pectin. Carrageenan is a negatively charged polysaccharide that was originally extracted from red seaweed. The large number of sulfate groups on the compound gives it its negative charge and so

By Derek Keats from Johannesburg, South Africa (Red seaweed, Plocamium sp.) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

By Derek Keats from Johannesburg, South Africa (Red seaweed, Plocamium sp.) [CC-BY-SA-2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons

may function well to remove the positively charged proteins in white wine. Pectin, on the other hand, is a negatively charged heteropolysaccharide compound with many carboxylic acid groups that has been shown to be effective in acidic dairy beverages.

The goal of the study presented today was to determine if carrageenan or pectic could be good alternatives to bentonite in removing proteins from Australian Chardonnay wines and to determine how these possible alternatives affect the chemical and aromatic characteristics of the finished wine.

Methods

Small Experiment

4 unfined juices from the 2009 vintage using Chardonnay, Sauvignon Blanc, Riesling, and Semillon grapes, as well as 4 unfined finished wines from the 2011 vintage using two Chardonnays and 2 Sauvignon Blancs (all from Adelaide Hills, Australia) were used in the preliminary experiment.

1mL of each wine sample was mixed with 0.5g/L of carrageenan and left in contact for 18 hours before the carrageenan was removed by filtration. All samples were performed in triplicate.

Large Experiment

Chardonnay must from the Langhorne Creek region of Australia (2009 vintage) was used for the large-scale experiment. Twenty 20L fermentations were prepared for the experiment. 30mg/L of pectinase was added, cold settled for 24 hours at 0oC, and finally racked.

The following 6 treatments were tested: 1) pectin added pre-racking; 2) carrageenan added pre-racking; 3) pectin AND carrageenan added pre-racking; 4) pectin added post-racking; 5) carrageenan added post-racking; and finally 6) pectin AND carrageenan added post-racking. The concentration of pectin used was 2g/L, and the concentration of carrageenan used was 0.25 g/L. Controls without carrageenan and/or pectin were also produced and tested.

After racking, standard fermentation practices were used on all treatment wines.

After going through a cold stability test, wines were bottled and capped with screw caps 4 months after fermentation ended.

For all wines, protein and polysaccharide content were measured, in addition to undergoing a heat test (measuring the amount of haze produced). The following were also measured and analyzed for all wines: alcohol, specific gravity, pH, titratable acidity, glucose, fructose, volatile acidity, free SO2, total SO2, brix, organic acids, metal content, color, and finally sensory characteristics.

A separate test determined how much bentonite was needed to produce a heat-stable wine (i.e. no haze formation).

For the sensory analysis, wines were evaluated by 30 expert AWRI tasters 10 months after bottling. The panel wrote their own notes about the appearance, aroma, and flavor of each wine, as well as whether or not they noted any faults in the wine.

Panelists were asked to determine which wine was different from the rest in a sample set of 3 wines each. They were given 5 sets representing all of the treatment wines. Panelists were isolated in tasting booths for the sensory analysis. Panelists were allowed a 30 second break in between analyzing each set.

Results

Small Experiment

• Carrageenan significantly reduced the amount of protein in all samples in which the compound was present in the small-scale experiment.

Large Experiment

• The use of carrageenan resulted in a decreased fermentation rate (3-11 days slower than the controls).
• The use of pectin did not affect the fermentation rate of wines.
• All fermentations to which carrageenan was added had problems with frothing.
• At day 12, polysaccharide content was higher in all treatments than in the controls.
• After bottling, there were no differences between treatments and controls in regards to polysaccharide content.
• Free SO2, total SO2, specific gravity and residual sugar were not affected by any of the treatments.
• Ethanol content was about 0.15% v/v lower in carrageenan-treated wines.
• Volatile acidity was lower in pectin-treated wines.
• pH was higher and acidity lower in pectin-treated wines.
o Acidity was lower due to lower tartaric acid content (no other acids were affected).
• Acidity was not affected by carrageenan treatment.
• All metals were in range of those commonly found in white wines.
• Fe and Al were decreased in most treatment wines.
• Mn, Zn, and Mg were significantly decreased in pectin-treated wines.
• Na was significantly higher in all treatment wines.
• K was significantly increased in pectin-treated wines.
• Pectin added pre-racking removed the Al prior to the start of fermentation.
• Al content was nearly zero for all treatments at bottling.
• At bottling, pectin added pre-racking had significantly higher levels of Ca than the control.
• Fe and Zn levels were similar at bottling to what levels were in the must for most treatments.
• Zn was 30% decreased in pectin added pre-racking compared to all other wines.
• Mg and Mn levels were significantly decreased in all pectin treatment wines.
• Na was increased in all treatments at bottling.
• K levels increased by 20% in pectin-treated wines.
• B, Cu, S, and P levels were not affected by any treatment.
• Metal concentrations in wines were more affected by pectin treatment than by carrageenan treatment.
o The authors suggested that if either of these are used as alternatives to bentonite, winemakers may want to consider adding micronutrients to make up for the changes listed above.
• Color was largely unaffected by the treatments, with no differences detected using the naked eye.
• In regards to protein removal, adding both pectin and carrageenan after racking was most effective.
o Most of the protein was removed prior to fermentation.
• By itself, carrageenan was more effective at removing protein than pectin.
o Pectin did not remove as many chitinases or thaumatin-like proteins compared with carrageenan.
• Pectin added after racking reduced haziness in wine by about 50%.
• Carrageenan treatments reduced haziness in wines by between 58 and 72%.
• The bentonite control treatment reduced haziness in wines by between 38 and 76%.
• Sensory analysis confirmed a significant different between the control wines and the wines treated with carrageenan after racking. No other differences were noted.
o It was not determined if this difference was better or worse, just that it was different.

Conclusions

The results of this experiment showed that the addition of both pectin and carrageenan effectively reduced the levels of haze-causing proteins in white wines, though carrageenan was slightly more effective than pectin. It is possible

By Agne27 (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

By Agne27 (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

that adding them together might be more effective, though those numbers were not supplied by the authors. It appears as though they are as effective as bentonite in removing protein from wine, so from a simple protein removal standpoint, both pectin and carrageenan would be good alternatives to bentonite.

There were some negative aspects to using pectin and/or carrageenan, including slowed fermentation rates, slightly lowered ethanol content and frothing in carrageenan, and altered metal content in both treatments. Finally, when carrageenan was added after racking, there was a change in the sensory profile of the wine, which may or may not be desirable.

Overall, the results of this study showed that pectin and carrageenan, when used separately or in concert, where just as effective as bentonite in reducing the protein levels in white wine and thus the haziness of white wine. However, I don’t think I’m ready to say go ahead and make the switch, as there are a lot of questions still left unanswered. The slowed fermentation rate and the frothiness in all fermentation batches when carrageenan was concerning to me, as winemakers would need to come up with effective strategies to avoid or work with these issues.

I was also concerned with the results of the sensory analysis, as it was not clear to me how the aromatic profile of the wine with carrageenan added after racking was affected. It seems like a somewhat poor experimental design to have a sensory analysis that gathers information on differences between wines yet not describe which one actually tastes better. It’s a simple question that could have received a quick answer, yet it was somehow overlooked. For all we know, that wine could have tasted significantly better than all the other treatments and controls!

Further analysis should examine the sensory changes further, as well as possible mechanisms for combating the slow fermentation rates and frothing issues. It would also be interesting to see if pectin or carrageenan added at different doses would be more or less effective than the doses analyzed in this study, and if adding them together would be better overall than adding them separately. Finally, how effective are these treatments using different white wines? I’d like to see a range of white wines compared.

What do you think about this study? What would you have done differently? What would you like to see come next in this line of research? Please feel free to leave any comments or questions!

Source: Marangon, M., Lucchetta, M., Duan, D., Stockdale, V.J., Hart, A., Rogers, P.J., and Waters, E.J. 2012. Protein removal from a Chardonnay juice by addition of carrageenan and pectin. Australian Journal of Grape and Wine Research 18: 194-202.

Posted in Chemistry, Enology

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The Influence of Oak Chips Added at Various Stages of Winemaking on Sensory Characteristics of Wine

Posted on April 3, 2013 by Becca| 4 Comments

 

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Welcome to The Academic Wino! If you are new here, please read the “About Me” page to find out more about myself and the blog. If you would like to receive free updates on articles like this by email, then sign up here or you can subscribe to the RSS feed. Also, check us out on Twitter, Facebook, Google+, and or Pinterest. Thanks for visiting!

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As many of you may already know, using oak barrels in wine fermentation and aging increases wine aromatic complexity and improves overall quality. The use of oak in wine is and has always been very popular, despite the fact that it costs more money to produce an oaked wine than it is to produce a wine made in stainless steel tanks. As a result of this cost differential, some wineries as well as home winemakers have been searching for alternatives to oak barrels that give similar aromatic and quality characteristics to the finished wine without the high costs.

There is some experimental evidence suggesting that application of oak extract to the vines during the growing season may impart oak flavor characteristics into the finished wine, however, it’s a practice that is currently just in the research and development phase, and is not yet widely practiced or accepted. In recent years, the use of oak chips instead of oak barrels has become much more popular, as it has been shown that using oak chips in wine fermented and/or aged in stainless steel tanks results in finished wines that are aromatically similar to wines that are fermented and/or aged in oak barrels.

Oak chips may be added to the wine at any stage during the winemaking process, and will result in varied styles of wine depending upon exactly when the chips were added. The goal of the study presented today was to examine the sensory

Agne27 at the English language Wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons

Agne27 at the English language Wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons

characteristics of one particular type of wine (Bobal) when placed in contact with oak chips at different stages throughout the winemaking process and to identify when during the winemaking process oak chip exposure will create the wine most similar to a wine kept in oak barrels.

Methods

Bobal grapes from a vineyard in the La Mancha region of Spain were used for this study and were harvested at their optimal ripening time. Grapes were separated into 7 batches and were all processed the same up until right after skin maceration. The following treatments were applied to the grape batches:

1. Control Wine: wine without the addition of oak chips.
2. Addition of oak chips during alcoholic fermentation.
3. Addition of oak chips during malolactic fermentation.
4. Addition of oak chips post-fermentation (1 week contact time).

The three oak chip treatments were split into two sub-treatments: 3g/L dose and 6g/L dose (total 7 treatments including control).

The oak chips used were a mix of French and American oak and had medium toast.

The rest of the winemaking process was pretty standard and the same for all treatments: manual punch downs, malolactic fermentation, racking, filtering, bottling, and storing. Finished wines were stored at 16-18oC until sensory analysis was performed. All treatments were performed in duplicate.

For all wines, the following were measured and analyzed: total acidity, ethanol content, pH, volatile acidity, total SO2, and free SO2.

For the sensory analysis, a carefully trained panel of 15 judges between the ages of 24 and 50 years old from the University of Castilla in La Mancha, Spain was selected. Panelists were specifically trained to analyze flavor descriptors in Bobal wines (both oaked and unoaked).

20mL of each treatment wine samples were given to the judges in standard wine glasses and covered with a watch glass in order to avoid volatile loss to the air. Sensory analysis took place in individual booths in a sensory analysis chamber. Panelists smelled and tasted the wines and recorded the aromatic and flavor descriptors they noted in each wine.

Results

• There were no significant differences between samples in regards to total acidity, volatile acidity, and pH.

Nose:
• Aromas on the nose of control wines (no oak chips added) were: red fruit, fresh, liquorish, pepper, sweet spices, leather, tobacco, and cassis.
• Wines with oak chips added at alcoholic fermentation saw a significant decrease in red fruit, liquorish, cassis, and pepper aromas.
• Wines with oak chips added at alcoholic fermentation saw a significant increase in sweet spices and woody notes at the higher 6g/L dose compared with the lower 3g/L dose.
• Wines with oak chips added at malolactic fermentation saw significant decreases compared with all wines in red fruit, fresh, pepper, and cassis aromas.
• Adding oak chips during malolactic fermentation resulted in significantly higher intensities of oak-derived aromas at the 6g/L dose compared with the 3g/L dose.
• Wines with oak chips added post-fermentation for one week were similar in character to wines with oak chips added during malolactic fermentation, however showed decreases in intensity of woody, vanilla, coconut, toast, and toffee notes.
• Wines with oak chips added post-fermentation for one week showed increases in red fruit character compared with wine with oak chips added during malolactic fermentation.
• 6g/L oak chip wines generally showed greater oak character than wines treated with 3g/L oak chips.
• Principle component analysis (PCA) grouped wines most similar to each other into two groups: 1) both wines with oak chips added at alcoholic fermentation and control wines; 2) both wines with oak chips added at malolactic fermentation and both wines with oak chips added post-fermentation for one week.
o The second group showed significantly more oak character than the first group.
o In the second group, the two wines with chips added at malolactic fermentation were greater in oak aromatic intensity than the wines with oak chips added post-fermentation for one week.

Taste:
• Control wines (no oak chips) had flavors of red fruit, liquorice, clove, pepper, leather and tobacco.
• All oak chip wines had significantly decreased red fruit flavors, with the wine treated with oak chips at malolactic fermentation having the least red fruit flavors.
• All oak chips wines had flavors of cinnamon, vanilla, wood, toast, and chocolate that were not present in the control wines.
• Wine treated with 6g/L of oak chips during malolactic fermentation had the most oak-like qualities compared with all other wines.
• All oak chip treatments reduced astringency in the wines.
• Wines treated with oak chips during malolactic fermentation had greater body than all other wines.
• Principle component analysis (PCA) grouped wines most similar to each other into two groups: 1) both wines with oak chips added at alcoholic fermentation and control wines; 2) both wines with oak chips added at malolactic fermentation and both wines with oak chips added post-fermentation for one week.
o The second group showed significantly more oak character than the first group.

Conclusions

The results of this study showed that the addition of oak chips at different times during the winemaking process resulted in finished wines with significantly different aromatic and flavor profiles. The addition of oak chips at any time resulted in wines with more oak-like character, however the amount of oak character was dependent upon the dose of oak chips as well as when during the winemaking process the oak chips were added. It was noted that astringency was also reduced when oak chips were added, and body was only affected when the oak chips were added during malolactic fermentation.

The authors suggested that any of the treatments would be acceptable alternatives to using an oak barrel, however, depending upon what style of wine

By Agne27 (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

By Agne27 (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

you wish to create will determine how much and when the oak chips should be added. According to the results, adding 6g/L of oak chips during malolactic fermentation produced the wine with the most intense oak flavors, however, all oak chip treatments possessed some oak-like character.

One treatment that I feel was missing from this experiment was the oak barrel treatment control. The results showed that oak chip treatments resulted in “oakier” wines compared with the stainless steel control, however, how does it compare with wines that are actually fermented and/or aged in a barrel? Is it comparable? A lot less?

It would also be interesting to see how wines made from other grape varieties are influenced by oak chip addition at different stages during the winemaking process.  Will we see similar results?  Or will we see different treatments emerging as the “oakier” style wines?

One other thing I would have liked to have seen is preference scores by the sensory panel. They described the aroma and flavor characteristics of each sample; however, they did not score whether or not they preferred one particular wine over another. Everyone has different tastes and preferences, of course, but it would have been at least somewhat interesting to see if the panel actually liked these wines or not.

I’d love to hear what you all think of this topic! Do you have any personal experiences you can share regarding oak chip-treated wines? What sort of future research would you like to see coming out of this study? Please feel free to comment!

Source: García-Carpintero, E.G., Gómez Gallego, M.A., Sánchez-Palomo, E., and González Viñas, M.A. 2011. Sensory descriptive analysis of Bobal red wines treated with oak chips at different stages of winemaking. Australian Journal of Grape and Wine Research 17: 368-377.

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