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Will The Brown Marmorated Stink Bug Be A Problem In Wine And Juice?

By: Jody Timer, Research Technologist

The brown marmorated stink bug (BMSB), Halyomorpha halys (Stal) is an invasive species that has become a major pest in the eastern United States. This pest originally became a sizable problem in Mid-Atlantic vineyards, including southwestern Pennsylvania, during the 2010 growing season and continues to be a large-scale problem. The Lake Erie grape belt is the largest Concord grape growing region in the world. The recent appearance of the brown marmorated stink bug in Lake Erie vineyards has the potential to become problematic. After the mild winter of 2015-2016, the numbers of BMSB in this area began to increase rapidly. This winter, frequent complaints have been received from homeowner concerning the presence of BMSB in their houses.

BMSB have been found in both grape foliage and grape clusters; they seek the moisture, sugar, and warmth on the inside the clusters (especially overnight) and they often migrate to the cluster’s interior close to harvest. This makes the possibility of BMSB inside the cluster very likely when these grapes are mechanically harvested and transported to the processor.

Brown Marmorated Stink Bug in a Grape Cluster

All BMSB life stages (5 instars) have been observed in vineyards indicating that grapes are a suitable crop for BMSB development, and all stages have been found to cause direct damage to grapes (Bernon 2004). At the Lake Erie Grape Laboratory, we have maintained an adult BMSB colony on a diet of Concord grapes with no apparent development problems. It has also been estimated that the presence of 5 BMSB per grape cluster may lead to 37% loss in grape yield as a result of BMSB damage (Smith et al. 2014). With the yearly increase of numbers of BMSB in the Pennsylvania vineyards, the possibility of BMSB tainting the juice produced in this area is becoming a primary concern to processors, growers, marketers, and consumers.

Life stags of the Brown Marmorated Stink Bug. Photo from: http://www.mda.state.mn.us/plants/insects/stinkbug.aspx

Insects produce small, volatile molecules that may be imparted to juice and wine during crush. Humans are able to detect these molecules at extremely low concentrations. For example, 2-isopropyl-3-methoxypyrazine (IPMP) from Multicolored ladybeetles (ladybug taint) is detectable at 0.30 ng/L concentrations in Concord grape juice (Pickering et al. 2008). BMSB have a distinctive odor which has been described as green, cilantro-like, which may or may not be off-putting within grape juice aroma. BMSBs produce taint associated compounds as allomones, alarm pheromones, aggregation pheromones, and kairomones. These compounds are mainly released from the dorsal abdominal glands in nymphs and paired metathoracic glands in adults (Baldwin et al. 2014). When BMSBs are crushed along with grape clusters, release of these compounds could potentially taint in the juice.

Multidimensional gas chromatography mass spectrometry (MDGC-MS) analysis of stressed BMSB, adults and nymphs, has been used to identify more than 39 compounds. The volatile compounds in the taint are tridecane, dodecane, trans-2-decenal and trans-2-undecen-1-ol. Tridecane and trans-2-decenal together constitute at least 70% of BMSB taint (Baldwin et al. 2014; Solomon 2013). Trans-2-decenal, is the major irritant and is believed to be responsible for the potent stink odor from BMSB. However, being an extremely unstable compound it can easily break down, and its degradation products lack the distinctive BMSB odor (Baldwin et al. 2014). When trans-2-decenal was added to red wine (Pinot Noir) the morning of testing, the detection threshold was in the low microgram per liter (ug/L) range (Mohekar et al 2015). However, because trans-2-decenal is unstable, this may not reflect what happens when juice is processed and stored. Joe Fiola from University of Maryland, reported that while 5-10 BMSB per 25 pound lug of white grapes imparted a perceptible taint in raw juice for up to four months in some cases, the taint was not perceptible in the wine after fermentation (Fiola 2011).  Mohekar and colleagues, from Oregon State, reported that trans-2-decenal, has a detection threshold in the ug/L range in Pinot Noir wines, and was able to be detected by tasters (Mohekar et al 2016).

Informal sensory testing with the on-site staff was performed at the Lake Erie Regional Grape Research laboratory. Small batches of grape juice were produced using a residential Kitchen Aid® juicer, and increasing numbers of BMSB were added. Batches of juice containing the equivalent of 0, 2, 10, and 25 BMSB per lug (~35 lbs. of Concord grapes) were tasted raw and after high-temperature, short-time pasteurization (HTST) by five staff members. In blinded triangle tests (2 blanks and 1 spiked sample), 5 of 5 individuals correctly identify the spiked sample of the 25 BMSB/lug juice (both raw and pasteurized); for the 10 BMSB sample, 4 of 5 correctly identified the spike in raw juice, and 5 of 5 identified the spiked sample for the pasteurized juice. The following month the pasteurized juice was re-tasted by 10 individuals and similar results were obtained.  These tests suggest 25 BMSB/lug are sufficient to induce a perceivable flavor change in Concord grape juice. Following this testing, a set of samples were processed at the Food Science laboratory of Penn State, using industrially relevant methods (equivalent to Welch’s Corporation processing techniques), to assess if the odor-causing compounds secreted by BMSB were stable enough to transfer through the juicing, processing, pasteurization, and storing of grape juice and therefore cause it to be rejected by consumers. Large scale sensory tests were then run with regular grape juice consumers to quantify rejection thresholds for BMSB-spiked, processed grape juice.

Grape clusters, with varying amounts of BMSB (0, 4, 8, 16, 24, and 32 BMSB, per 35 lbs), were crushed and destemmed; the juice was pasteurized, clarified and blended. Following storage for 8 weeks (2 months after initial processing), sensory testing was performed with grape juice consumers in the controlled sensory testing facility to determine rejection thresholds for different levels of BMSB. Sensory testing was then repeated 8 weeks later (4 months after initial processing).

Despite the use of BMSB levels that clearly caused a noticeable change in the flavor of processed juice in pilot testing, we were unable to find a level of BMSB that caused rejection in consumers following processing and storage at either time point.

As the area’s BMSB population increases, this research will be notably important for processor to determine threshold levels at harvest. This research suggest that taint from BMSB at high but realistic doses for the Lake Erie grape-growing region will not influence consumer acceptability. Conversely however, our results may not generalize to smaller producers in the area who make grape juice using exclusively from Concord grapes. Typically, this juice is sold as fresh juice with a limited shelf life. These smaller growers and producers should be aware of the possibility of taint in their juice especially with the increasing numbers of BMSB in the region. Pre-harvest scouting for BMSB should be conducted to determine if a pre-harvest BMSB insecticide spray should be applied.

https://youtu.be/VzIpLHatLHc

https://youtu.be/el9HLnMLN90

 

References:

Baldwin, R.L. IV, A. Zhang, S.W. Fultz, S. Abubeker, C. Harris, E.E. Connor, and D.L. Van Hekken (2014) Hot topic: Brown marmorated stink bug odor compounds do not transfer into milk by feeding bug-contaminated corn silage to lactating dairy cattle. J. Dairy Sci. 97. 1877-1884.

Bernon, G. (2004) Biology of Halyomorpha halys, the brown marmorated stink bug (BMSB) Final Report—USDA APHIS CPHST Project T3P01. USDA APHIS.

Fiola, J.A. (2011) Brown Marmorated Stink Bug (BMSB) Part 3-Fruit Damage and Juice/Wine Taint. Timely Viticulture. University of Maryland extension,

http://www.grapesand fruit.umd.edu. Accessed October, 2016

Mohekar. P. (2016) Brown Marmorated Stink Bug (BMSB), Halyomorpha halys Taint in Wine: Impact on Wine Sensory, Effect of Wine-processing and Management Techniques. Dissertation Oregon State University

Mohekar, P., Tomasino, E., Wiman, N.G., (2015) Defining defensive secretions of brown marmorated stink bug, Halyomorpha halys. Presented at the 2015 Annual Meeting of the Entomological Society of America, Minneapolis, MN

Pfeiffer, D. G., T. C. Leskey and H. J. Burrack, (2012) Threatening the harvest: The threat from three invasive insects in late season vineyards, pp. 449-474. In N. J. Bostanian,

Pfeiffer, D., J. Fiola, B. Lamp, K. Rane, A. Nielsen, D. Polk, B. Petty, D. Ward, M. Saunders, J. Timer, C. Hedstrom, P. Mohekar, N. Wiman, E. Tomasino and V. Walton, (2013) BMSB in Vineyards and Wines. www.stopbmsb.org/stopBMSB/assets/File/Research/BMSB…/Vineyards-Vaughn.pd . Accessed September 2016

Pickering, G.J., Karthik, A., Inglis, D., Sears, M. and K. Ker, (2008). Detection Thresholds for 2-Isopropyl-3-Methoxypyrazine in Concord and Niagara Grape Juice. Journal of Food Science, 73 (6): S262-S266.

Prescott, J., Hayes, J. E., & Byrnes, N. K. (2014). Sensory Science. In N. K. V. Alfen (Ed.), Encyclopedia of Agriculture and Food Systems (pp. 80-101). San Diego: Elsevier.

Smith, J.R., Hesler, S.P., and Loeb, G.M., (2014) Potential Impact of Halyomorpha halys (Hemiptera: Pentatomidae) on Grape Production in the Finger Lakes Region of New York. J. Entomol. Sci. 49, 290–303. doi:10.18474/0749-8004-49.3.290

Solomon, D., D. Dutcher, and T. Raymond, (2013) Characterization of Halyomorpha halys (brown marmorated stink bug) biogenic volatile organic compound emissions and their role in secondary organic aerosol formation. J. Air Waste Manag. Assoc. 1995 63, 1264–1269.

Welch’s Corporation, www.Welch’s.com Accessed August 2016.

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2017 PA Research Symposium Provides Research-Based Practicality for PA Grape Growers and Winemakers

By: Denise M. Gardner

The Pennsylvania Wine Marketing and Research Board (PA WMRB) annually awards researchers and graduate students grants to explore pertinent topics to the Pennsylvania wine industry.  For the 2016 – 2017 fiscal year, four projects were awarded industry-funded grants.  Results from these four projects will be presented at the 2017 Symposium, co-hosted by the PA WMRB, Penn State Extension, and the Pennsylvania Winery Association (PWA).

Registration is being organized through the PWA, and can be found here:

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This year’s Symposium, held on Wednesday, March 29th at the Nittany Lion Inn (University Park, PA) will only run in the morning and is packed with 5 sessions of information pertinent to both the enology and viticulture fields in Pennsylvania.  At the close of the Symposium a lunch will be provided for all attendees.

Guest Speaker has Enology and Tannin Focus

The WMRB Symposium key guest speaker is Dr. Catherine Peyrot des Gachons, Winemaker Consultant at Chouette Collective.  Dr. Peyrot des Gachons has assisted Pennsylvania wineries with enhancing their quality production for several years.  She will be speaking towards her tannin and wine aroma matrix research that she has been working on at the Viticulture and Enology Department through the University of Montpellier (France).

Dr. Catherine des Gachons, winemaker consultant, will be the key guest speaker at the 2017 PA Wine Marketing & Research Board Symposium.

Dr. Catherine des Gachons, winemaker consultant, will be the key guest speaker at the 2017 PA Wine Marketing & Research Board Symposium.

Tannins: Modulation of wine structure and aroma

From environmental factors on tannin biosynthesis to human interventions to modulate tannin content in wine what do we know and what can we do to modulate wine structure. Can this tannin content impact wine aroma?  The presentation will focus on few main points of interest with practical applications.

 

Enology-Focused Presentations

An additional enology-based presentation will feature Laurel Vernarelli, a graduate student in Dr. Ryan Elias’s lab within the Penn State Department of Food Science.  Laurel’s presentation will be an extension from Dr. Gal Kreitman’s work that was presented last year on predicting reductive off-odors in wines.  Laurel will explore the use of copper fining in wine production and the potential impact it may have on wine quality.  Given the prevalence of reductive off-odors, including hydrogen sulfide, and heavy reliance on copper fining, this topic should be of considerable interest to most wineries.

Laurel Vernarelli will give an update on treating reductive and hydrogen sulfide aromas/flavors with copper sulfate at the 2017 PA Wine Marketing & Research Board Symposium.

Laurel Vernarelli will give an update on treating reductive and hydrogen sulfide aromas/flavors with copper sulfate at the 2017 PA Wine Marketing & Research Board Symposium.

Reconsidering copper fining in wine

This presentation will include a brief overview of copper fining, along with the impact of reductive thiols and recent findings describing the effect that copper has in wine. A method for using immobilized copper materials in place of copper fining is described. Depending on the result obtained, winemakers can make informed decisions for use of alternative fining techniques when dealing with reductive issues.

 

Viticulture-Focused Presentations

For those with an interest in viticulture, this year’s program promises to deliver some key updates.  Bryan Hed, Research Technologist for the Department of Plant Pathology, will present his annual updates regarding disease management for Pennsylvania vineyards.  For those that are frequent blog followers, Bryan is a lead contributor to the important seasonal reviews.  These tend to be very popular posts for growers and his presentations are always informative and practical.  If you missed the 2016 seasonal reviews, you can find them here:

Bryan’s talk at this year’s Symposium is a continued study with results collected over 2 years, which helps initiate trends and suggestions useful towards growers.

Bryan Hed from Penn State University will review current disease management techniques for the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Bryan Hed from Penn State University will review current disease management techniques for the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Updates on Grape Disease Management Research

Fruit zone leaf removal can be a very beneficial practice in the management of harvest season bunch rot. Bryan will start his presentation by briefly reviewing the pros and cons of different timings of this practice. In addition, leaf removal by hand is very expensive and labor intensive, and with the increasing scarcity and rising cost of hand labor, mechanization is crucial to increasing cost effectiveness and adoption of this practice, no matter what the timing. Bryan will follow up with an in depth discussion of the progress made toward mechanizing an early, pre-bloom leaf removal and comparing its effectiveness over a variety of wine grape cultivars and training systems during the past two seasons.

 

Maria Smith, Ph.D. candidate in Dr. Michela Centinari’s lab, will discuss her research regarding early leaf removal in Gruner Veltliner vines.  Maria and Dr. Centinari have previously written a blog post pertaining to leaf removal strategies for Mid-Atlantic vineyards, which could act as an excellent primer to Maria’s presentation in March.  Her presentation will deliver two-years (2015, 2016) of data regarding the effects of early leaf removal and cluster thinning techniques on Gruner Veltliner vines.

Penn State Plant Science Ph.D. Candidate, Maria Smith, will discuss her research on early leaf removal and cluster thinning techniques for Gruner Veltliner at the 2017 PA Wine Marketing and Research Board Symposium.

Penn State Plant Science Ph.D. Candidate, Maria Smith, will discuss her research on early leaf removal and cluster thinning techniques for Gruner Veltliner at the 2017 PA Wine Marketing and Research Board Symposium.

Vine response and management costs of early leaf removal for yield regulation in V. vinifera L. Gruner Veltliner

Early leaf removal (ELR) and cluster thinning (CT) were applied and compared for yield regulation in Grüner Veltliner over the 2015 and 2016 growing seasons.  Early leaf removal was performed at two different times, trace-bloom and fruit-set. We compared the effects of ELR and CT on grape quality, vine health, and economic costs to un-thinned vines.

 

Finally, Dr. Michela Centinari will follow up with further results regarding sprayable products to reduce frost damage in wine grape vineyards.  Michela’s frost research has been a prominent topic at previous Symposiums, and is often featured here on the blog site.  While the updated results that will be presented at the 2017 Symposium have not yet been reported through Penn State Extension, please see some of her past blog posts pertaining to frost control and freeze damage in the vineyard:

Dr. Michela Centinari will discuss her current research findings pertaining to frost protection in the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Dr. Michela Centinari will discuss her current research findings pertaining to frost protection in the vineyard at the 2017 PA Wine Marketing & Research Board Symposium.

Spray-on materials: can they reduce frost damage to grapevines?

Dr. Centinari will present results of studies conducted to test the efficacy of sprayable products as a low-cost frost protection strategy. Two materials Potassium-Dextrose-Lac (KDL) and a seaweed extract of Ascophyllum nodosum, were tested for their cryo-protective activity using a controlled-freezing technique on several grapevine cultivars.

 

We hope to see you there!

Tasting Chambourcin: Part I

By: Denise M. Gardner

Note: Sensory descriptions of wines produced by the grape variety, Chambourcin, are based on individual observations, tastings, and a collection of notes obtained through various Chambourcin tastings including many different individuals.

At the Central Pennsylvania regional winery meeting held at Brookmere Winery, attendees and I had the opportunity to taste through a series of Pennsylvania-grown and produced Chambourcin wines.  This was actually one of the first all-Chambourcin wine flights that I have been able to taste, and I was quite encouraged by what I was tasting in the glass.  Paula Vigna, writer for The Wine Classroom via Penn Live, has since written an article on the tasting titled, “Chambourcin’s ceiling: Maybe higher than originally thought.”

Chambourcin: A Description

Chambourcin is a French-American hybrid wine grape variety that was bred by crossing Seyve-Villard 12-417 (Seibel 6468 x Subéreux) with Chancellor*, commercialized in 1963 (Robinson et al. 2012).  Despite Chambourcin’s vigor and relative tolerance to disease pressure in humid climates, anecdotally the wine does often appear preferred by many Vitis vinifera winemakers.

As a wine, Chambourcin’s strength is its vibrant red color and supple, soft mouthfeel due it is relatively lack of course tannin on the palate.  These features often make it a valuable red wine blending possibility, especially considering the relative consistency of obtaining Chambourcin fruit every vintage.  However, the smoothness of the wine often is a frustration by many eastern winemakers looking for more depth and [tannin-related] mouthfeel in their red wines.  When coupled with Chambourcin’s notorious ability to retain acidity, often above 7 g/L of tartaric acid (depending on where and how it is grown), the lack of perceived tannin can make the wine taste relatively thin and acidic.

The acidity associated with the Chambourcin grape variety often appears retained when grown in cooler climates.  For example, in Pennsylvania, Chambourcin produced in North East, PA (Erie County) often has relatively higher TAs compared to Chambourcin grown in southeastern, PA (e.g., Berks County).  From a grape growing perspective, all winemakers should expect this phenomenon.  However, Chambourcin can retain a higher acidity even when grown in the warmer southern parts of Pennsylvania.  Based on observation, the variety seems to maintain its acidity when it is not thoroughly crop thinned.  As Chambourcin is an incredibly vigorous variety, and as you will see from the tasting, producers hoping to drop the acidity often crop thin grape clusters while on the vine.

When looking at the tannic composition of Chambourcin, it is likely that much of the tannin content associated with Chambourcin is lost during primary fermentation.  Dr. Gavin Sacks at Cornell University is studying this situation associated with many hybrid wine fermentations.  As Dr. Sacks discussed at the 2016 Pennsylvania Wine Marketing & Research Board (PA WMRB) Symposium in March, tannins come from 3 different components of the grape: the stems, the skin, and the grape seeds. During the fermentation process, anthocyanins (red pigments) and skin tannin is extracted quickly, usually before the product starts to ferment.  Seed tannin is extracted more slowly, typically throughout primary fermentation and extended maceration processes.  Dr. Sacks’ lab (Springer and Sacks, 2014) and previous research (Harbertson et al. 2008) have shown, grapes produced outside of the western U.S. generally have lower concentrations of tannin available in the grape.  While available tannin in the grapes does not necessarily correlate with tannin concentrations in the finished wine, many eastern U.S. winemakers will add exogenous tannin pre-fermentation, during fermentation, and/or post-fermentation to help improve mouthfeel and potentially increase substrate availability for color stability reactions.  However, even with exogenous tannin additions, Dr. Sacks has found that many of the tannins associated with hybrid fermentations end up lost during the fermentation process due to protein-tannin binding complexes that pull tannins out of the wine.  The higher protein concentration associated with the hybrid grapes has been linked to disease resistance mechanisms that the varieties were originally bred for, and is more thoroughly explained in Dr. Anna Katharine Mansfield’s recent Wines & Vines article, “A Few Truths About Phenolics.”

Additionally, Chambourcin has been noted to have a relatively neutral red wine flavor, lacking a concentrated pop of fruit and using non-descript aromatic or flavor descriptors like: red cherries, red fruit, red berries, stemmy, herbal, or even millipedes. And yes, I have heard one or two consumers actually reference a millipede aroma when tasting Chambourcin.

Tasting Chambourcin Produced in PA

Flight of Chambourcin Wines tasted at the June 2016 Central PA Regional Wine Meeting, hosted by Brookmere Winery. Photo by: Denise M. Gardner

Figure 1: Flight of Chambourcin Wines tasted at the June 2016 Central PA Regional Wine Meeting, hosted by Brookmere Winery. Photo by: Denise M. Gardner

The official flight (Figure 1) of Chambourcin wines that I had put together included:

  • Galen Glen Winery 2014 Stone Cellar Chambourcin
  • Penns Woods Winery 2014 Chambourcin Reserve
  • Vynecrest Winery 2014 Chambourcin
  • Pinnacle Ridge Winery 2013 Chambourcin Researve
  • Allegro Winery 2012 Chambourcin

Additionally, Brookmere Winery, Armstrong Valley Winery, and Caret Cellars (Virginia) added Chambourcin wines to taste.  The formal wine tasting turned out to be quite a unique experience.

I saw a few over-arching sensory themes within these wines:

  • Reduced acidity: While I did not personally measure the pH and TA for these wines, the perception of acidity was not as obvious, overly perceptible, or offensive.
  • Soft, supple mouthfeel: Even with a couple of the wines that were perceived as “more tannic,” these wines were soft and easy-drinking.
  • Use of oak barrels: Many of the producers were opting for some production in actual oak barrels as opposed to using oak alternatives. Type of oak ranged from French, American, and Hungarian.
  • Higher alcohols: Alcohol concentrations for these wines ranged from 13-14%, likely due to extended hang time in the vineyard, allowing for an increase in sugar accumulation.
  • Two emerging aromatic profiles: A couple of the wines were very fruit-forward and fruitier than what is normally expected from Chambourcin. The other wines were less fruit-forward, however, they did retain a fair amount of red fruit aromatics in addition to the complex aroma nuances: earthiness, tobacco, toasted oak, vanilla, and tobacco.  Many tasters commented on the general concentration of aromatic nuance associated with many of the wines we tasted.

In general, the relative depth, cleanness, and fruit expression of these wines was impressive.  Perhaps this tasting clearly indicated that although many winemakers struggle with finding the “right fit” or style for their Chambourcin, the level of quality associated with the wine has definitely improved within the last 5 years.  At the very least, the level of quality associated with this flight of wines was encouraging for hybrid red wine producers.

Additionally, Brookmere Winery provided a real treat from their cellar library: a 1998 Chambourcin produced by Brookmere Winery (Figure 2) when Don Chapman owned the winery.  If you appreciate older wines, then this Chambourcin would truly impress you.  Not only did it express the “old wine” honey-floral character loved by many wine enthusiasts, but the red fruit aromas and flavors were still boldly expressed in the wine.  The color was intense and dynamically red, and there was a fine perception of firm tannins on the palate.  Overall, the tasting of this wine gave me the perception that not only did this wine still have plenty of room to continue aging in the cellar, but that Chambourcin, as a wine varietal, had positive potential for aging for more than 10 years.

Figure 2: 1998 Chambourcin Produced by Brookmere Winery. Photo by: Denise M. Gardner

Figure 2: 1998 Chambourcin Produced by Brookmere Winery. Photo by: Denise M. Gardner

Given that most of this post is based on my own experiences, perceptions, and information gathered from growers and producers pertaining to Chambourcin, I would welcome any additional experiences with the variety (as a grape or as a wine) in the comments section.

While this post has documented Chambourcin as a grape variety and a small snap shot of sensory perceptions from a handful of producers in Pennsylvania, next week’s post will focus on production techniques to improve the quality Chambourcin red wines.

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For more information on upcoming regional meetings and the types of tastings to be held at those FREE events, please visit: http://extension.psu.edu/food/enology/events

 

Resources

Harbertson, J.F., R.E. Hodgins, L.N. Thurston, L.J. Schaffer, M.S. Reid, J.L. Landon, C.F. Ross, and D.O. Adams. 2008. Variability of tannin concentration in red wines. Am. J. Enol. Vitic. 59:210-214.

Mansfield, A.K. January 2015. A few truths about phenolics. Wines & Vines.

Robinson, J., J. Harding, and J. Vouillamoz. 2012. “Chambourcin.” pg. 218-219. Wine Grapes. ISBN: 978-0-06-220636-7

Springer, L.F. and G.L. Sacks. 2014. Protein-precipitable tannin in wines from Vitis vinifera and interspecific hybrid grapes (Vitis ssp.): differences in concentration, extractability, and cell wall binding. J. Agric. Food Chem. 62(30):7515-7523.

 

*Authors Note: Since the publication of this article, a few growers and grape breeders have alluded to the improperly reported parentage of Chambourcin. While it is generally reported and cited as such, it is understood among some wine grape experts that Chancellor is not likely a parent to Chambourcin. For more information on determining parentage of given grape cultivars, please refer to: http://www.vivc.de and search the cultivar name of interest. 

 

Regional Winery Meetings Scheduled for Pennsylvania Wineries in Summer 2016

By: Denise M. Gardner

Each calendar year, Penn State Extension works with the state wine industry to schedule “regional” meetings with local producers.

Regional meetings are kindly and financially supported by the PA Wine Marketing and Research (WMRB) Board and Pennsylvania Winery Association (PWA), as part of the annual operating expenses that are granted to the Penn State Extension Enology position each fiscal year.  The financial support is, in part, contributed by each Pennsylvania winery in the annual assessment on the gallons of wine produced across the state, which are submitted to the PA WMRB.  It is this funding mechanism that makes these visitations possible on an annual basis, and all Pennsylvania wineries are encouraged to attend.

These regional visitations by the Extension Enologist were designed to be convenient for local industry members in terms of location.  While industry members, or perspective industry members are welcome to attend any of the meetings, the purpose of these meetings is for me to get out into various parts of the state while making traveling a bit more convenient for industry members.

Regional meetings are free for industry members or prospective members to attend.

All regional meetings are hosted at a local winery, and meeting locations are listed below and on the Penn State Extension Enology website.

Each region organizes their regional visits differently, and they are designed to be beneficial for that region of industry members.

Regional meetings all have a unique structure.  Many are only a few hours long, offer a production tour of a local winery, and many include a tasting.  In the past, regional meetings have included anything from question and answer sessions on a production tour:

Denise Gardner discusses winemaking with Sharon Klay from Christian Klay Winery.

Denise Gardner discusses winemaking with Sharon Klay from Christian Klay Winery. Photo from: Mark Chien

To tasting bench trials created by some of the local wineries:

Bench trials set up during a Central PA Regional Winery Meeting. Photo from: Denise Gardner

Bench trials set up during a Central PA Regional Winery Meeting. Photo from: Denise Gardner

Wine tasting and sensory evaluation. Photo from: Denise Gardner

Wine tasting and sensory evaluation. Photo from: Denise Gardner

To hosting benchmark tastings on specific wine varieties:

Wines from Around the World Benchmark Tasting. Photo from: Denise Gardner

Wines from Around the World Benchmark Tasting. Photo from: Denise Gardner

To holding a short educational program on a topic of specific interest to that region.

Dr. Kathy Kelley presents her research on tasting room design at a regional meeting in Erie County. Photo from: Denise Gardner

Dr. Kathy Kelley presents her research on tasting room design at a regional meeting in Erie County. Photo from: Denise Gardner

Additionally, these visitations by the Extension Enologist offer several benefits to the local industry, including:

  • meet with existing producers to discuss potential problems or challenges within the winery,
  • visit with potentially new or new producers within the wine community,
  • introduce new producers to existing operations to enhance networking and collaboration across the state,
  • answer questions pertaining to wine production and quality, and
  • review Penn State research updates pertinent to the wine community.

The tentative agendas for each regional meeting, in addition to their scheduled date, for 2016 are listed below.

The program at Brookmere will include a production tour with a question and answer period by all attendees.  Additionally, Denise will conduct an educational tasting on local Chambourcin wines produced across Pennsylvania. This was created by request from the regional producers in order to get a better idea of how Chambourcin tastes throughout the state.

This regional visit will follow the day after the “Stabilize Your Wine – Filtration, SO2, and Potassium Sorbate” workshop hosted by Cornell and Penn State Extension at the CLEREL Station in Portland, NY.  This workshop requires pre-registration (see the attached link), and anyone is welcome to attend with paid registration.

On August 3rd, Denise will visit individual wineries to discuss winery-specific problems or to keep Denise current on what is happening in the winery.  To schedule an appointment with Denise, please contact Andy Muza in the Erie County Extension Office.

The southwestern regional meeting will be held at La Casa Narcisi Winery and include a production tour.  Denise will host a small educational session on high potassium winemaking with a tasting of the high potassium wines (i.e., Merlot, Cabernet Sauvignon) that were produced by Penn State during the 2015 harvest.  Wineries are welcome to bring their own wines for feedback and welcome to stay through lunch, which can be purchased at the restaurant on site at La Casa Narcisi.

  • Northeastern PA: Date and location TBD, but please reserve August 30th or 31st on your calendars

Currently, the date and final agenda for the northeastern part of the state is being discussed.  But, please continue to check the “PSU Extension V&E News” listserv and Extension Enology website for updates.

More information, and updates, on each regional visit can be found at: http://extension.psu.edu/food/enology/events. Pre-registration is NOT required for anyone to attend regional meetings.

While there is not a Southeastern PA regional meeting currently scheduled, there are several events hosted in the southeastern section of PA that are conveniently located for those regional wineries.  Wine Trails in the southeastern quadrant of PA are encouraged to contact Denise for specific visitations.

The most current workshop on the calendar includes the Sensory Defects for Fermented Beverages and Distilled Spirits workshop, held on June 9th, which will be hosted in Collegeville, PA (Montgomery County).  Registration for this workshop is required, and details for the program can be found at the above link.

As is the past, the Penn State Extension Enologist acts as a resource for Pennsylvania wineries when production problems or questions arise.  You can find contact information In addition to the list of educational programming designed for the local industry, Penn State Extension is filled with:

  • Online resources via Penn State Extension’s website
  • The “Wine & Grapes U.” blog site, which includes a yearlong calendar of local/regional/national events and local sales and job opportunities.
  • Annual workshops including the Wine Quality Improvement (WQI) Short Course held every January, the upcoming Sensory Defects for Fermented Beverages and Distilled Spirits workshop, the PA Wine Marketing & Research Board Symposium, and many additional workshops that cover a multitude of topics. Previous workshop topics covered: micrbiological techniques for wine production, the use of sulfur dioxide in the winery, pre-harvest preparation, benchmark wine tastings, blending, and more!
  • Wine Made Easy Fact Sheets, which can now be found on the Extension website! These are quick print outs designed to help winemakers in the winery.  Visit the link for all of the topics currently published.
  • The weekly “Penn State Extension V&E News” listserv, distributed every Friday to keep industry members current on research, real-time issues in the vineyard and winery, and upcoming events pertinent to this industry.

Customer Survey Opportunity for Wineries

By: Kathy Kelley

My very first post for this blog focused on using surveys to learn about consumers’ tasting room experiences (http://bit.ly/1QMfEtu).  I described a few easy to use and free tools (e.g. SurveyMonkey.com, SurveyGuizmo.com) that can be used to create a questionnaire.

I feel very strongly about gathering input from consumers about their attitudes and behaviors pertaining to winery tasting rooms in the region and how tasting rooms can encourage repeat visits.  As you know very well, there is limited data available that describes the Pennsylvania wine consumer, impressions of their tasting room visits, and wine preferences.  Collecting this data is essential, as described in an article published by Brian Fletcher on the MarketingProfs.com website: “Market research…is essential to you and your brand’s long-term success…[it] will keep your brand afloat while companies who fail to make research a high priority drown” (http://bit.ly/1NerOZW).

Hence, I have decided to “put my money where my mouth is” and I am creating a survey that tasting room owners/operators can use to collect this valuate data.  But, wait, there’s more…

What I am offering

My offer includes not only the survey questions and gathering responses via my SurveyMonkey.com subscription, but I will also send a monthly summary to each participating tasting room that will contain responses specific to their operation.  Because of the potential number of survey responses, I will only be able to provide summary data.  Summary data for each question will look similar to the following image (shown just for demonstration purposes).

Dec_Kathy_summary question

Who might benefit

My thought is that this offer could help a variety of tasting rooms.  For example, those:

  • without a system in place to capture consumer sentiment,
  • who are collecting data from customers but would be interested in learning responses to these additional questions,
  • interested in collecting the data digitally,
  • unable to fully administer a customer satisfaction survey for one reason or another, etc.

Sample questions and limitations

The overall goal of this survey is for owners/operators to learn from visitors what tasting room aspects they find appealing and what components of the experience may need to be reevaluated and enhanced or amended.

I will be working on a draft of questions until the survey launches in late winter 2016, but I have a core list of questions that I feel will benefit a majority of tasting rooms.  They include:

  • date and time of day (morning, afternoon, evening) of their most recent visit to your tasting room,
  • who they visited the tasting room with,
  • if they participated in a tasting, educational event/tour, festival or activity, etc. when at the tasting room,
  • if they made a purchase and what they purchased,
  • how they would rate their overall tasting experience, interaction with tasting room staff, products available for purchase, visual appeal of the tasting room, etc. using scales (e.g. 1 to 5, 1 to 7),
  • their interest in events and activities that you have an interest/ability to offer in the future,
  • if they were a first time visitor, how they learned about your tasting room and what encouraged them to visit,
  • how to encourage repeat visits to your tasting room (e.g. collaboration/cross promoting with other businesses, tasting room only offerings and events), and
  • demographic, socio-economic status of the survey respondent (e.g. age range, sex), and similar questions (e.g. distance traveled from home to visit the tasting room, other businesses that they visited in the area).

After consumers submit their survey they will be directed to your tasting room website, or other URL that you specify.

While each tasting room is unique and I’m sure that it would be preferable for each to have a customized survey, the amount of time to craft several different surveys is beyond what I have available.  But, those willing to participate can chose to remove certain questions and I will work with them to create up to two questions that are specific to their operation.

How to proceed

This first effort will be more of a pilot test to:

  • determine demand for such a tool/service,
  • work out any issues that arise,
  • get a general idea if this is a benefit for tasting rooms, and
  • gage the amount of time I would need to devote to this project each month.

Since this is a new offering, and just with introducing a new good or service in your tasting room, I would like to trial this with 20 tasting rooms.  Though preference will be given to Pennsylvania tasting rooms, if space is available I am willing to include businesses located outside the Commonwealth.

You may indicate your interest in participating by filling out a short survey/online form by Friday, January 15, which you can access by clicking on this link: http://svy.mk/1O6VMfr

Questions ask for your contact information, URL for your tasting room website, location of your primary/main tasting room (if you have more than one), and whether you agree that:

  • you will participate in the pilot test for the entire duration (one year with an estimated start date in late winter) unless a situation occurs that causes me to end the study early,
  • you will be able to delete certain questions and add up to two questions (which I will help you create),
  • responses collected from your tasting room visitors will be kept confidential and that any reports (blog posts, presentations, and similar) developed will be the result of combining data collected from all participating tasting rooms, and
  • tasting room visitors who access the survey will first need to read a consent form and agree to participate in the study before responding to the customer satisfaction survey.

After the 20 tasting rooms have been selected and the final list of questions has been developed, each tasting room will receive a URL to their survey.  The URL can be posted on websites, distributed via email, printed on material that is distributed to tasting room visitors, and so on.

Potential benefits/opportunities that your participant will provide

If you have been reading the marketing blog posts published on this site, you know that researchers from Pennsylvania, New York, and New Jersey received funding from the USDA Federal State Marketing Improvement Program (http://1.usa.gov/1YkCPRw) to survey consumers residing in the three state about their wine purchasing and consumption habits.  Though we are still conducting surveys and analyzing data, you can read some of the results by clicking on this link: http://bit.ly/1IWfTRK.  Results from this study will further benefit the industry.

I hope that some of you will find this offer interesting and chose to participate.  I think that this is a great opportunity for tasting rooms to learn from visitors and for the wine and grape group at Penn State to learn about potential areas of wine marketing research.  In addition, with the group’s goal of providing information to the industry through Extension efforts, your participation will also allow us to help educate tasting rooms in the region about tasting room visitors’ needs, wants, and interests.  Our hope is that this consumer-based survey can help us tailor ways to help you improve your tasting-room marketing initiatives and increase foot traffic and sales.

If you would like to participate, please click on the following link and complete the survey by Friday, January 15th: http://svy.mk/1O6VMfr

Please contact me at kmk17@psu.edu if you have any questions.

Reflections: Winemaking at Penn State

By: Denise M. Gardner

I can officially say that I have now been involved with 5 harvests here at Penn State, with my first harvest in 2011.  Returning to Pennsylvania from California in 2011 could not have been a greater challenge to an incoming newbie, and I think it will forever be one of the most difficult vintages I have had the experience to deal with to date.  Not only did I manage to lose an entire lot of finished wine down the drain (long story…), but I recognized the need to bring PA-produced research wines to Pennsylvania’s growing wine industry during a daunting season from a weather perspective.  Additionally, I saw an opportunity to educate students on how to make wine while they helped me process fruit from the research vineyards.  In that first year, 5 lucky college seniors helped me process about 8 different varieties from the NE-1020 “multi-state evaluation of wine grape cultivars and clones” project, which was being financially supported by a multi-state SCRI grant.

Looking back today, I now see that the 2011 vintage provided me with a starting point to work with students and a series of winemaking lessons for future vintages that I continue to recall even today.

I was actually one of those bright-eyed students back in my younger days.  I stumbled upon Penn State Extension and Mark Chien by pestering local Extension educators on how to grow grapevines.  I still recall the many opportunities Mark, specifically, provided for me despite my age or lack of wine knowledge.  Mark taught me how to plant a vineyard, from site selection to digging holes for a trellis, how to monitor vine growth through proper pruning techniques, how to ferment grapes into wine, and the various stages involved in production that went beyond the basic texts on how to make wine.  I connected with industry members and was awarded an experience to intern at Lallemand in Toulouse, France before I reached my freshman year in college.

Figure 1: Extension Enologist, Denise Gardner, developed an interest in wine grape growing and production throughout high school.  Photos, from left to right, include an annual fermentation lesson during a high school agriculture class, building a trellis system at the local high school, grape vines after 2 years of growth at the high school vineyard, and a lesson from past Extension Viticulturist, Mark Chien, on how to properly prune grapevines at a PA vineyard.  Photos provided by: Denise M. Gardner

Figure 1: Extension Enologist, Denise Gardner, developed an interest in wine grape growing and production throughout high school. Photos, from left to right, include an annual fermentation lesson during a high school agriculture class, building a trellis system at the local high school, grape vines after 2 years of growth at the high school vineyard, and a lesson from past Extension Viticulturist, Mark Chien, on how to properly prune grapevines at a PA vineyard. Photos provided by: Denise M. Gardner

When I arrived to Penn State in 2011, I had a memory of the opportunities Extension awarded me and a goal of working with students that may have an interest in wine production.  I still laugh when I recall a number of students that experienced a harvest at a local winery, only to tell me it was “the hardest thing they have ever had to do.”

While many may not make the connection, food science offers an incredible foundation of knowledge that is beneficial for winemakers and those whom wish to go into fermented beverage production.  Students engage in a series of classes to develop a foundation in chemistry, microbiology, and biotechnology.  Additionally, they learn important processing parameters that are affiliated with winemaking: sanitation, quality control practices, safety when processing, proper sampling techniques, and experimental practices to improve food/beverage products.

For that reason, the annual harvest and production of wine with use of undergraduate and graduate students’ support has blossomed into many positive ventures:

  • Since 2010, Penn State Food Science and several Pennsylvania wineries have sponsored student co-ops at wineries during vintage seasons. These experiences educate students in wine production, and specifically provided venues for “real world” experiences in the wine industry.
  • Undergraduate students have embarked on undergraduate research experiences pertaining to wine research within the College of Agricultural Sciences. Several of these projects have benefited the local wine industry.
  • Graduates from Food Science have started to “harvest hop” to the southern hemisphere for winemaking and production experiences internationally. Virginia (Smith) Mitchell, head winemaker at Galer Estate Winery, traveled to Australia in the winter months of 2013 while Allie Miller will travel to New Zealand for the 2016 harvest.  These experiences bring a global perspective and education that facilitate innovative changes to the growing Pennsylvania wine industry.
  • Several students have benefited from permanent placement in the wine and fermented beverage industries upon graduation, and many have committed to Pennsylvania operations. The experience gained through research winemaking here at Penn State is invaluable and leaves them with base knowledge in wine production.
  • Many students volunteer for Extension programming, which gives them the opportunity to present research and educational experiences to industry members as well as network with potential employers (you!).
  • Graduate research has flourished. Both Dr. Ryan Elias and Dr. Michela Centinari have several graduate students that are working on applied research projects which address winemaker and grower needs reflected in previous industry needs assessments.
  • Since 2011, the number of research wines being made has more than quadrupled. Today, we have outgrown the equipment I used in 2011 and outgrown our storage capacity for research wines.  The wines produced at Penn State are annually evaluated at regional Extension events.

With such a positive focus on student development and interaction with Pennsylvania’s grape and wine industry, the 2015 vintage was expected to be our best vintage yet!

The 2015 growing season did not leave much hope for Pennsylvania grape growers and winemakers, and I can recall a series of summer meetings in which winemakers from across the state asked me if I was prepared to deal with a lack of fruit and a bunch of rot in our research winemaking curriculum.  Luckily, as Michela will reflect upon next week, the season shaped up to be one of the best I have experienced in my time here at Penn State.

For 2015, we recruited 10 interested undergraduate students for the 2015 harvest season to assist with the research harvests and wine production.   This is double the quantity of students that typically enroll in an independent study experience associated with enology.

Students participate in regular wine processing operations, which can be seen in Figures 2 – 7: crushing, pressing, monitoring fermentation, and completing wines through malolactic fermentation.  Additionally, at the end of the semester, each enrolled student presents on a wine grape variety of interest.

Many students arrive with a genuine interest in fermentation science, or would like to get more experience in food production.  Many of them leave the fall semester with future undergraduate research opportunities, internships/co-ops at wineries, or develop an expectation to graduate with permanent placement in the fermented beverage industry.

Figure 2: The undergraduate students start each fall with a review of lab analysis techniques to learn how to properly analyze juice and wine, which comes in handy during the harvest season.  Photo by: Denise M. Gardner

Figure 2: The undergraduate students start each fall with a review of lab analysis techniques to learn how to properly analyze juice and wine, which comes in handy during the harvest season. Photo by: Denise M. Gardner

Figure 3: Crush is an essential part of the independent study class and graduate student research.  Careful care is taken by the students to ensure that proper sanitation is taken, accurate yields are measured, and that treatments are adequately separated into replicate fermentations. Photos by: Denise M. Gardner

Figure 3: Crush is an essential part of the independent study class and graduate student research. Care is taken by the students to ensure that proper sanitation is utilized, accurate yields are measured, and that treatments are adequately separated into replicate fermentations. Photos by: Denise M. Gardner

Figure 4: Prepping inoculums for primary and malolactic fermentations is an important part of what the students learn how to do throughout the semester.  Here, Blair and Cara prep hydration nutrient and yeasts for inoculations. Photo by: Denise M. Gardner

Figure 4: Prepping inoculums for primary and malolactic fermentations is an important part of what the students learn how to do throughout the semester. Here, Blair and Cara prep hydration nutrient and yeasts for inoculations. Photo by: Denise M. Gardner

Figure 5: Students also learn how to properly inoculate wines for primary fermentation.  A: Marielle, Stephanie, Joe, Garrett, Gary and Blair inoculate Riesling wines; Photo by: Denise M. Gardner; B: Denise and Gary inoculate Cabernet Sauvignon musts; Photo by: Marlena Sheridan.

Figure 5: Students also learn how to properly inoculate wines for primary fermentation. A: Marielle, Stephanie, Joe, Garrett, Gary and Blair inoculate Riesling wines; Photo by: Denise M. Gardner; B: Denise and Gary inoculate Cabernet Sauvignon musts; Photo by: Marlena Sheridan.

Figure 6: Racking techniques without a pump. [From left to right] Liv, Maria, and Marielle rack Riesling juice into replicate fermentation carboys.  Photo by: Denise M. Gardner

Figure 6: Racking techniques without a pump. [From left to right] Liv, Maria, and Marielle rack Riesling juice into replicate fermentation carboys. Photo by: Denise M. Gardner

Figure 7: Pressing [white/rosé] juice or finished [red] wine is always an experience. A: Gary, George, and Garrett press rosé to prepare for overnight settling, B: Stephanie loads the press with crushed white berries, C: Allie fills a carboy of finished red wine, D: Laura, Marlena, Gary, Garrett, and Blair preparing for red wine pressing, and E: Marielle sits in the splash zone for red wine pressing.  Photos by: Denise M. Gardner

Figure 7: Pressing [white/rosé] juice or finished [red] wine is always an experience. A: Gary, George, and Garrett press rosé to prepare for overnight settling, B: Stephanie loads the press with crushed white berries, C: Allie fills a carboy of finished red wine, D: Laura, Marlena, Gary, Garrett, and Blair preparing for red wine pressing, and E: Marielle sits in the splash zone for red wine pressing. Photos by: Denise M. Gardner

I can’t wait to share some of the 2015 wines with the local industry at the March 2016 PA Wine Marketing & Research Board Symposium or at future Extension Enology events.

As a general reminder, many of these projects are financially supported through the multi-state Grape Wine Quality Eastern U.S. Initiative SCRI grant (which partially funds the NE-1020 variety trial research program), the PA Wine Marketing and Research Board, and the Crouch Fellowship, among other grant agencies.

Here are just a few snap shots that depict everything that we are currently working on for the 2015 harvest season:

Figure 8: This year’s NE-1020 variety trial projects include yeast trials, an evaluation of tartaric acid additions to red wine varieties grown in high potassium vineyard sites (A), and pre-fermentation juice treatments in Vidal Blanc wines (B).  Photos by: Denise M. Gardner

Figure 8: This year’s NE-1020 variety trial projects include yeast trials, an evaluation of tartaric acid additions to red wine varieties grown in high potassium vineyard sites (A), and pre-fermentation juice treatments in Vidal Blanc wines (B). Photos by: Denise M. Gardner

Figure 9:  The Crouch Fellowship currently supports a project pertaining to the impact of spray-on frost protection products on grape and wine quality.  A: Graduate student, Maria Smith, gets ready for a full day of processing after a full day of harvest. B: Marielle and Cara monitor the red wine fermentations through daily punch downs, temperature logs, and Brix measurements.  Photos by: Denise M. Gardner

Figure 9: The Crouch Fellowship currently supports a project pertaining to the impact of spray-on frost protection products on grape and wine quality. A: Graduate student, Maria Smith, gets ready for a full day of processing after a full day of harvest. B: Marielle and Cara monitor the red wine fermentations through daily punch downs, temperature logs, and Brix measurements. Photos by: Denise M. Gardner

Figure 10: Graduate student, Marlena Sheridan, takes a photo of a cluster representation for her research project on red wine color stability. Photo by: Denise M. Gardner

Figure 10: Graduate student, Marlena Sheridan, takes a photo of a cluster representation for her research project on red wine color stability. Photo by: Denise M. Gardner

Figure 11: Graduate student, Laura Homich, enjoys time in the Noiret vineyard for her research project that focuses on the effect of canopy management practices on rotundone (black pepper flavor) development in Noiret grapes and wine.

Figure 11: Graduate student, Laura Homich, enjoys time in the Noiret vineyard collecting berry samples for her research project that focuses on the effect of canopy management practices on rotundone (black pepper flavor) development in Noiret grapes and wine. Photo by: Maria Smith

Figure 12: Graduate student, Gal Kreitman, prepares inoculates on Vidal Blanc in relation to a project on the influence of copper on thiol-containing aroma/flavor compounds. Photo by: Denise M. Gardner

Figure 12: Graduate student, Gal Kreitman, prepares inoculates on Vidal Blanc in relation to a project on the influence of copper on thiol-containing aroma/flavor compounds. Photo by: Denise M. Gardner

Figure 13: Another full year of research winemaking at Penn State – vintage 2015.  Photo by: Denise M. Gardner

Figure 13: Another full year of research winemaking at Penn State – vintage 2015. Photo by: Denise M. Gardner

To follow all of our annual research harvest activities, please ‘Like’ us on Facebook: www.facebook.com/PennStateExtensionEnology

 

Winemaking Practices Believed to Affect Red Wine Color Stability

By: Denise M. Gardner

In previous blog posts, we covered an introduction to what anthocyanins (red wine color pigments) are and how they can be stabilized in wine. Additionally, Marlena Sheridan recently discussed current research on acetaldehyde-bridging amongst anthocyanins or anthocyanin and tannin substances in wine.

This post will evaluate several techniques used during red winemaking, and what the scientific literature has found regarding their impact on red wine color stability.

Anthocyanins undergo three main phases during the course of a wine’s life:

  • Development in the grape
  • Extraction during primary fermentation
  • Stabilization through the life of the wine
anthocyanin life

Phases associated with anthocyanins through a wine’s life.

While vineyard development is an important aspect of color stabilization, as starting anthocyanin concentration will ultimately determine potential processing decisions for winemakers, the following processes are reflective of winemaking techniques believed to affect red wine color stabilization. As you siphon through the various techniques, please remember that there is no one fix-all solution to improve red wine color stability. Wine is a complex matrix, and results may vary from one variety to the next, or from one vintage to the next.

Cold Soak

Cold soak is a pre-fermentation process in which grape must is held at low (≤10°C, ≤50°F) temperatures. There are various ways to execute a cold soak step in wine production:

  • Placing a holding vessel (i.e., a macrobin) in a cool, ambient environment
  • Use of tank temperature control
  • Use of dry ice

Cold soaking grape must is believed to increase anthocyanin extraction pre-fermentation. Increasing anthocyanin extraction would make stabilization reactions more favorable, pushing equilibrium to building stable anthocyanin-complexes through and after fermentation.

However, several studies have investigated the use of cold soak on various red wine varieties. In two Pinot Noir studies (Gerbaux 1993, Feuillat 1996, Sacchi et al. 2005*), detrimental effects to color were found on Burgundian wines when cold soak was used pre-fermentation. Similarly, Heatherbell et al. (1996) found no difference in wine color for those wines that were cold soaked versus the non-cold soaked controls.

A study that tested freezing must, however, had a different impact on the finished wine color.  The variety evaluated was Merlot, and musts were frozen with dry ice.  An increase in anthocyanin concentration by 50% and increase in overall tannin concentration by 52% was found in finished wines in which grape must had been frozen pre-fermentation, compared to an untreated grape must, control wines (Couasnon 1999, Sacchi et al. 2005*).  Freezing may have a greater effect on anthocyanin concentration, as freezing physically causes berry cells to burst and release its contents.

Definition of Cold Soak

Definition of Cold Soak

Practical Winemaking Application: Winemakers do not need to utilize a cold soaking step to increase anthocyanin extraction or improve red wine color stability, as most research suggests there is no effect regarding red wine color stability. However, it is important to note that little research has been conducted regarding potential extraction of phenol and/or tannin complexes (including polymeric pigment content) during the cold soak step.

Saignée

Saignée is the French term for “bleed,” and is utilized as a winemaking technique for making rosé wines by “bleeding off” free-run juice from macerated red grapes. While the free-run juice may be used for rosé production, many winemakers utilize the saignée technique to concentrate (increase extraction) of anthocyanins and tannins in the juice that will be made into a finished red wine. Secondary effects may also increase flavor concentration.

In 1972, Singleton found that the use of saignée increased the flavonoid and anothocyanin concentrations in the concentrated red wine, four months post-fermentation. Gerbaux (1993) found slight increases in color (through sensory analysis) and phenolics of young Pinot Noir wines that had been subjected to saignée practices. However, unlike Singleton, Gerbaux’s study did not find increases in anthocyanin concentration. However, Gawel et al. (2001) found initial increases in anthocyanin concentrations at the end of primary fermentation in pressed Syrah wines, but these concentrations were depleted after 6-months post-fermentation. This study did not investigate the fate of monomeric anthocyanins, and depleted concentrations of anthocyanins were likely caused by potential polymerization or adsorption of anthocynanins onto various other wine constituents (e.g. dead yeast cells, tartrates).

saignee

Definition of Saignee

 

Practical Winemaking Application: While the causes of potential increased color stability are unclear, the use of saignée to concentrate red grape must appears to have a positive outcome on the wine’s color stability properties. Currently, there is no evidence that removal of 10% free-run juice is less beneficial than removal of 20%. However, as saignée is a concentration method, if the grapes are of low quality, the winemaker will only concentrate other poor quality components (i.e. off-flavors, excessive tannin, etc.) with use of this technique.

Micro-oxygenation (Micro-ox)

Micro-ox is the “addition of dissolved oxygen at controlled dosage rates at or less than the oxygen uptake rate of wine” (Paul 2002). According to Dykes (2007), typical dosages rates range from 2 – 90 mg of oxygen per liter of wine per month. The utilization of micro-ox is believed to affect the stabilization of red wine color pigments, and therefore requires adequate starting material (i.e. anthocyanins, phenolics/tannins) in order for this method to be effective.

Theoretically, when used between primary fermentation and malolactic fermentation, the integration of dissolved oxygen should provide the chemical constituents needed to initiate polymeric pigment formation of monomeric anthocyanins. Micro-ox is used as a driving force to influence acetaldehyde concentration and influence acetaldehyde-bridged complexes previously described by Marlena Sheridan. One previous study has shown no rise in acetaldehyde contraction by use of micro-ox (Pozo et al. 2010). However, this study did find that wines subjected to micro-ox treatment did have an increased concentration of sulfite-resistant pigments. Many other wine experts have written on the use of micro-ox, and there is a world of scientific literature available regarding its use and outcomes in red wines, with varied guaranteed consensus. Additionally, micro-ox has potential to alter other characteristics of wines, including mouthfeel or flavor, in both positive and negative ways, which is often dependent on the starting wine chemistry. The extent of this summary does not nearly cover the depth of research regarding micro-ox in wine production, and will be tabled for a later date.

Definition of micro-oxygenation (micro-ox)

Definition of micro-oxygenation (micro-ox)

Practical Winemaking Application: The use of micro-oxygenation may be a powerful tool to enhance anothocyanin stabilization. Winemakers are encouraged to work with the unit’s supplier or a consultant with micro-oxygenation experience prior to implementing this strategy into processing procedures. Anecdotally, at Penn State, we have noticed little success of micro-oxygenation to improve red wine color when used on wines that have relatively low anothocyanin concentrations (<200 mg/L GAE).

Thermovinification

Thermovinification is a technique that uses a brief heating step to grape must or juice, and subjecting it temperatures above 60°C (140°F). It is believed that thermovinification enhances both extraction and stabilization of anthocyanins.

Auw et al. (1996) found that the use of thermovinification increased the concentration of free, monomeric anthocyanins in both Cabernet Sauvignon and Chambourcin wines. Additionally, this study also found increased concentrations of phenolics in the Chambourcin wine treated with thermovinification pre-fermentation, and a lower phenolic content in Cabernet Sauvignon wines treated with thermovinification. This emphasizes that solutions to improve color stability may vary depending on the grape variety and its heritage (i.e. native variety vs. hybrid vs. V. vinifera). Additionally, Sacchi et al. (2005) also concluded that it is necessary to have some skin contact time with grape skins after thermovinification treatment in order to enhance extraction of anthocyanins.

Practical Winemaking Application: The use of thermovinification to improve red wine color stability may be a practical tool for red wines, especially those red wines with minimal aging requirement. Thermovinification is not recommended for red wines destined for long term aging. It should be noted that thermovinification may alter flavor of the finished wines. A winery should evaluate the potential sensory impact of thermovinification prior to committing all wines to this process.

Extended Maceration

Extended Maceration is the process of allowing skins and seeds in contact with the finished red wine, post-fermentation, for an extended period of time. Various studies researching the effects of extended maceration on red wines have found increased concentrations of tannins, especially tannins from grape seeds. However, this process has not been shown to increase extraction or concentration of anthocyanins.

Auw et al. (1996) found that a thermovinification treatment was more effective at increasing phenolic composition compared to extended maceration for Chambourcin wines, but that for Cabernet Sauvignon wines, extended maceration was more effective at increasing phenolic concentrations. Watson et al. (1994, 1995) also found an increase in flavanol and polymeric pigment extraction in Pinot Noir wines that underwent extended maceration.

Definition of Extended Maceration

Definition of Extended Maceration

Practical Winemaking Application: Extended maceration will not increase free monomeric anthocyanin concentrations. This practice should only be utilized for winemakers wishing to increase tannin-based extractions.  For a review on why the effects of extended maceration may be focused on phenolic extraction, please see Dr. Anna Katharine Mansfield’s recently published article, “A Few Truths About Phenolics,” in Wines & Vines.

Delayed Malolactic Fermentation (MLF)

The most current scientific literature on delayed MLF is coming out of Dr. James Osborne’s lab in Oregon. This practice is literally as it sounds: winemakers allow a wine to finish primary fermentation and wait (without addition of sulfur dioxide) for a specific period of time until MLF progresses naturally or is inoculated. This is an anthocyanin stabilization processing technique.

On studies in Pinot Noir, James and Osborne (2014) found that a 200 day delay in MLF was required for wines that went through MLF to reach a similar concentration of polymeric pigment, statistically, as the control wine that did not undergo MLF. It is important to remember that in order to maintain stability of wines not treated with sulfur dioxide, adequate temperature control (i.e. maintaining the cellar at 50-55°F or 10-13°C) will cause polymeric pigment formation reactions to progress slowly, which may influence why so much time is needed in delaying MLF. While increase temperature would increase the rate of polymeric pigment formation reactions, the increase in temperature also puts wines at greater risk for microbial spoilage.

Definition of Delayed MLF

Definition of Delayed MLF

Practical Winemaking Application: The jury is not out on this practice! Although some winemakers swear this practice works, it is important to remember than many wineries do not run “control” treatments for various practices. As there is much vintage-to-vintage variation amongst wines, it is challenging to draw solid conclusions from commercial wineries that do not utilize a control treatment. Currently, the literature states a delay in MLF may effectively improve color, but the time required for that delay may not be practical from a commercial operation standpoint.  Additionally, winemakers must maintain effective strategies at monitoring potential spoilage during a vulnerable period of time when the wine is not protected by preservatives (sulfur dioxide).

While this blog post covers several techniques believed to affect red wine color stability, the review article by Sacchi et al. covers several additional topics including: yeast selection, fermentation temperature, the effects of sulfur dioxide, carbonic maceration, the use of pectolytic enzymes, and utilization of pump-overs and punch downs during primary fermentation.  The review of the current scientific understanding of these practices (up to research literature published through 2005) can be found in the American Journal of Enology and Viticulture (AJEV).

Sacchi et al. 2005* The following authors (Couasnon 1999, Feuillat 1996, and Gerbaux 1993) were included in the Sacchi et al. 2005 review article. As initial research article was in another language, information regarding these studies was obtained from Sachhi et al. 2005.

 

Literature Cited

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