Viticulture and Enology Extension News Washington State University

SPRING 2013

CONTENTS NOTE FROM THE EDITOR With budbreak teasing us to an early start in 2013, the calm before the “storm” is seem- ingly short. This period is a great time to catch up on your reading, and prepare for the upcoming growing season. As such, I highly encourage you to pick up a copy of the 2013 Grape Pest Management Guide for Grapes, check out wine.wsu.edu, and of Native Plants...... Page 2 course, enjoy this issue of VEEN. Berries & Water...... Page 4 In this issue, we take a look at the Vineyard Beauty with Benefits project, learn a little bit about how berries balance their water, and get an update on a newly-named disease New Grape Disease...... Page 6 in vineyards across the USA (and Washington!). We also have an update on the Wine Sensory Lab and a great summary on how the wine matrix can effect tannins.

Sit back, enjoy a barrel sample, and read on! ENOLOGY Michelle Moyer Viticulture Extension Specialist Sensory Lab Update...... Page 8 WSU-IAREC TDN Thresholds...... Page 9 Wine Matrix...... Page 10

OTHER NEWS Tech Transfer Intro...... Page 13 Calendar of Events...... Page 13 FIND US ON THE WEB: EDITOR www.wine.wsu.edu/research-extension Michelle M. Moyer, PhD Information when you need it. That is the power of the internet! Visit the WSU Viticulture and Enology Research and Extension website for valuable information regarding research programs at WSU, timely news releases on topics that are important to your business, as well as information regarding upcoming workshops and meetings. It is also a valuable site for downloading our most recent Extension publications, in addition to archived articles and newsletters you can print on demand. Find quick WSU Extension programs and em- links to AgWeatherNet, the Viticulture and Enology Degree and Certificate programs, ployment are available to all without as well as to other Viticulture and Enology related resources. discrimination. Evidence of noncompli- Find us on Facebook ance may be reported through your local WSU Extension office. Go to: www.facebook.com/WSU.Vit.Enol.Ext and “Like” the page!

1 Biological Control Enhanced by Native Plants By David James, WSU-IAREC For the past two seasons, entomologists at WSU- IAREC, with support from the Washington wine grape industry, Western Sustainable Agriculture, Research and Education (WSARE), and the Northwest Center for Small Fruits Research (NCSFR), have been identifying and counting the beneficial insects attracted native flowering plants growing in and near viticultural areas in eastern Washington.

After examining more than 2500 sticky traps associated with over 100 different plant species, the team has devised a preliminary ranking of these native plants in terms of their ability to attract natural enemies of pests.

The number one ranked plant with the highest Figure 1- Flowering sagebrush (Artemesia tridentata) is a highly attractive to parasitic wasps and average number of all types predatory bugs. Photo by David James. of beneficial insects was the common sagebrush nauseousus). The familiar yellow, late The next phase of our project is aimed (Artemesia tridentata; Fig. 1). Flowers summer-autumn flowers of this species at identifying and clarifying the benefits of this ubiquitous shrub-steppe plant attracted an average of 413 beneficial of native plants in sustainable pest attracted a mean of 505 beneficial insects per trap with predatory bugs, management for wine grape vineyards. insects per trap; most of these were ladybeetles and bees well represented For this, five native plant species that parasitic wasps, including high in addition to parasitic wasps. attract a large diversity and number numbers of Anagrus wasps, important of beneficial insects, and may have in the biocontrol of grape leafhoppers. Other ‘high-performance’ plants value as between-row ground covers in included: Western Clematis (Clematis vineyards, have been selected for trial The number two ranked species ligusticifolia), Northern Buckwheat in a WSU wine grape vineyard. was Gray Rabbitbrush (Ericameria (Eriogonum compositum), Showy Milkweed (Asclepias speciosa, Fig. 2), With support from the WSU-BIOAg Yarrow (Achillea millefolium, Fig. 3) and Program, the selected native plants, Snow Buckwheat (Eriogonum niveum). including Showy milkweed, Yarrow, To learn more about the For more details on these ranks check Northern Buckwheat, Snow Buckwheat, out the WSARE progress report at: and Coyote Mint, will be established Vineyard Beauty with in the vineyard during spring 2013. Benefits project, check www.wavineyardbeautywithbenefits.com Although some supplemental irrigation out their website at: may be required for establishment, www.wavineyardbeautywithbenefits.com Flowering native plants that attract these native plants will not require both a large and a diverse number irrigation in future seasons. Baseline beneficial of insects may havedata on pest and beneficial insect significant potential as enhancers populations will be collected during You can also “Like” the of natural predator populations and 2013, but evaluation of plant impact project on Facebook: therefore be of benefit to wine grape on these populations will not be http://www.facebook.com/ growers. Wine grape pest management possible until flowering occurs in 2014. pages/Vineyard-Beauty- in eastern Washington is largely based with-Benefits-Restoring- on conservation biological control (i.e., An unusual partner in this research will using native natural enemies of pests). be the Washington State Penitentiary Habitat-for-Beneficial-In- Thus, cultivation and conservation of (WSP) in Walla Walla. As part of an sects/112777002135559 native plants that attract predators and innovative partnership established parasitoids should improve the efficacy and sustainability of biological control. continued on Page 3

2 Native Plants: con’t continued from Page 2 between WSU and WSP in 2012, selected offenders will be trained in insect identification and used to process leaf and sticky trap samples from the native plant vineyard trial.

The plants chosen for the vineyard trial were selected from a list of 40 to 50 plants shown to have potential as enhancers of biological control in wine grape vineyards. Thus, there are many more plants that need testing in vineyard situations, both as ground covers or refugia plantings. Funding will be sought for this testing both in WSU and commercial vineyards but we encourage vineyard owners to try some of our recommended native plants themselves. A full list of native plants with potential in eastern Washington vineyards for improving pest management will be published later this year.

Aside from the direct benefits to grape pest management, growing native plants in or near your vineyard also benefits the conservation of these plants. Benefits also extend to the other fauna which use these plants as hosts or shelter, such as threatened species of native butterflies and bees.

The majority of plants identified thus far are also important for pollinators Figure 2- Showy milkweed (Asclepias speciosa) is a highly attractive plant to predatory and parasitic insects and pollinators. Photo by David James. and some are also host plants for butterflies. Consequently, in partnership with the Washington Department of Fish and Wildlife, we are establishing a vineyard butterfly project in which we will assist interested growers in fine-tuning their native plant habitat for the dual benefits of better pest management and butterfly conservation.

Clearly, the potential of restoring native habitat to vineyards is considerable both in terms of practical as well as community and aesthetic benefits. The opportunities for capitalizing commercially on these benefits are also self-evident. Figure 3- Yarrow (Achillea millefolium) is a hardy native plant that attracts a wide range of beneficial insects. Photo by David James.

3 Water Economy in Grape Berries By Yun Zhang, PhD Candidate, WSU-IAREC

Water is critical in both viticulture and amount of water they can wine production. Many processes in take in. The extensibility of the plant are dependent on water. As the skin is not limitless, and a solvent, water determines the con- it declines during ripening centrations of all of the compounds [2]. If there is too much (sugars, acids, phenolics, etc.) that are water coming in but not essential in determining fruit quality. enough water going out, At maturity, approximately 70-80% of the pressure exerted on the berry fresh weight in grapes is water skin could crack or split the [1]. Therefore, one could not overes- berries (Fig. 2A). If grape timate the importance of berry water berries are not able to get economy to commercial yield and ber- enough water “deposits” ry quality. to match the “withdraw- als”, shrinkage will occur Four components of berry water econ- (Fig. 2B). For example, omy. Grape berries are storage organs, pre-veraison berries could with growth and ripening that are en- shrink during hot days, es- tirely supported by the water and sugar pecially with severe water flows from the vine. Imagining grape stress that limits water sup- berries as a checking account, there plies from both the xylem are two streams of “direct deposit” in and phloem. terms of water – xylem and phloem. Figure 1- Diagram of a grape berry and pedicel showing Xylem is the main pipeline transport- Shrinkage could also hap- the four components of berry water economy. Red (phloem) ing water and minerals into berries. pen late in the season with and blue (xylem) arrows indicate water inflows. Yellow Water flow in the xylem follows thehy - extended hang-time. This (xylem backflow) and pink (berry transpiration) arrows indicate water loss. Note that transpiration occurs at any drostatic pressure gradient, the same kind of shrinkage is due to surface while phloem and xylem are bundles imbedded mechanism at work in a garden hose: dehydration, not a physi- within the berry and pedicel. Photo by Yun Zhang. water always flows “downhill”. ological disorder (e.g., sour shrivel). The berries shrink conducted several experiments with On the other hand, phloem transports because they lose water through xy- three varieties (V. labruscana ‘Concord’, sugary water, and it is the only source of lem backflow and transpiration. Late- Merlot, and Syrah), to figure out what sugar to berries. Our grape “checking season shrinkage (dehydration) may could happen if we artificially restrict account” does not just receive depos- cause substantial yield loss; by the time one or both of these pathways. its, water is also withdrawn as a normal shrinkage is visible, berries have lost physiological process. Berries are not about 10% of their weight. After ber- In a field experiment, we used a com- the only organs on a vine that require ries reach approximately 23 °Brix, the mercial anti-transpirant to restrict berry water and are always competing with phloem stops delivering sugar to ber- transpiration. Also, to stop xylem back- other organs, mainly leaves, for water. ries. Therefore, any increase in °Brix flow, we carefully drilled through the When leaves are rapidly transpiring, during hang-time is due to dehydra- peduncles of clusters to destroy xylem like during a hot day, the pressure gra- tion; there is no net gain of sugar con- tissue without damaging the phloem. dient points towards them. Thus xylem tent. From one of our experiments, we Treatments were applied just before flow can be reversed, going from the estimated that Vitis vinifera ‘Merlot’ véraison. Both treatments slowed color fruit to the leaves. This is what we call and ‘Syrah’ berries gained 2.2 and 2.8 change and delayed ripening (Fig. 3). xylem backflow. Water also evaporates °Brix per 10% weight loss, or had 4.7 (transpires) from the berry surface. Al- and 3.9% weight loss to gain 1 °Brix at By harvest, berries with either restricted though the rate of berry transpiration ripeness. Therefore, it is important to transpiration or xylem backflow had is much lower than that of leaves (ap- evaluate the cost in yield to reach a cer- accumulated 33% less sugar compared proximately 100 times less), it is still tain °Brix level if extended hang-time is to untreated ones, and the combina- important, especially late in the season required. tion of these two treatments almost when the water “deposits” from the xy- doubled the effect (65% less sugar). lem and phloem into the berry, cease. Berry transpiration and xylem back- Besides less sugar accumulation, treat- The four components of the berry wa- flow enhance ripening. There is no ed clusters had a much higher cracking ter economy are summarized in Fig. 1. doubt that getting stable supplies of incidence than untreated ones (e.g., water and sugars through the xylem 7-fold higher with restricted transpira- Balance in berry water “account” is im- and phloem is essential to the normal tion). portant. In order to mature normally, ripening of grape berries. However, grape berries need to balance their wa- what roles do berry transpiration and In a separate experiment with potted ter checking account. Unlike our bank xylem backflow play during berry de- vines, we used a custom-designed root checking account, grape berries have velopment? Should we stop berries pressure chamber (Fig. 4) to stop xy- a “ceiling”, the skin, which limits the from losing water to prevent yield loss? In order to answer these questions, we continued on Page 5

4 Berry Water Economy, con’t continued from Page 4

causes delayed ripening, reduced sugar A accumulation, and increased cracking.

Irrigation and rainfall. Irrigation and rainfall directly influence berry water economy. Supplying water directly to the soil (e.g., drip irrigation) has dif- ferent effects than supplying water to the canopy (e.g., overhead sprinkler irrigation or rainfall). When roots take up water from the soil, how much wa- ter will be delivered into the berries is controlled by pressure gradients, as de- scribed previously. B However, with overhead irrigation or rainfall, water is intercepted by the canopy. This increases canopy and fruit zone humidity, thus decreasing berry transpiration. Water can also move into the berries through their skin [3]. Thus, the berry water economy becomes un- balanced in the overhead irrigation/ rain situation, and the risk for berry cracking is increased.

The difference in the effects between supplying water to the soil and to the canopy becomes more dramatic as ber- Figure 2- When the berry water economy is unbalanced, berries may (A) crack when water ries near maturation. As ripening pro- inflows exceeds water outflows, or (B) shrink when water inflow is inadequate to balance gresses, berries naturally receive less water loss. lem backflow. As before, berry sugar restricted clusters. Additionally, if the continued on Page 9 accumulation decreased when xylem pressure exerted on the skin exceeds backflow was stopped. its extensibility, berries will crack, as we saw in our experiment. The science behind our findings shows that grape berries do not get an unlim- It is to an evolutionary advantage that ited sugary water supply through the grape berries have more than one phloem. This long-distance transport pathway to ensure the important sug- from leaves (sugar factory) to berries ar delivering process will not be eas- is sophisticated and the “language” of ily disturbed. In our experiments, we their communication is pressure. Simi- have found that berry transpiration lar to the mechanism in the xylem, yet varies drastically with changes in envi- more complex, phloem sap from the ronmental conditions: any decrease in leaves to the berries also follows a pres- air temperature or increase in humid- sure gradient. ity reduces berry transpiration. Berry transpiration is evidently not a reliable When phloem delivers sugary water to pathway to dispose of excess phloem berries, incompressible water goes into water, but grape berries have another the berries along with unloaded sugars, pathway, xylem backflow, to ensure and pressure is transmitted to the ber- the continued delivery of sugary water ries. If the pressure cannot be released, through the phloem and also, to avoid as was the case of treated clusters in our cracking. experiments, the increased pressure in the berries will become a signal telling To conclude, berry transpiration and the leaves stop sending sugary water. xylem backflow are both necessary This is why we observed reduced sugar during berry development. When one Figure 3- Clusters with restricted transpira- tion (right) ripened more slowly than the accumulation and delayed ripening or both pathways are restricted, the unrestricted ones (left). Photo by Yun Zhang. in transpiration and xylem backflow unbalanced berry water “account”

5 Update: A New Graft-Transmissible Grape Disease in WA By Naidu Rayapati, Sudarsana Poojari, and Olufemi Alabi, WSU-IAREC

During the past several growing sea- though not iden- sons, we have observed symptoms tical, to Grape- that look like grapevine leafroll disease vine Red Blotch (GLRD) in Washington vineyards; how- Disease reported ever, there were some consistent dif- in New York and ferences between the symptoms we California. It is observed and classic GLRD symptoms likely that symp- (See WSU Extension Bulletin #EB0762). tom expression For example, leaves on these symp- may vary between tomatic vines typically did not show own-rooted vines downward rolling of the leaf margins, planted in Wash- a characteristic of vines with GLRD. An- ington vineyards other difference, seen in red Vitis vinif- and grafted vines era cultivars, included small, irregular, planted in New red-colored areas between major veins York and Califor- on mature leaves originating from the nia. Because of bottom sections of affected vines which this, and the fact appeared after véraison. The discol- that symptoms Figure 1- Vitis vinifera ‘Merlot’ grapevine showing GRD symptoms. Mature leaves at the bottom portion of the vine are showing red ored areas on leaves expand with time can vary widely leaves, red blotches and red veins. Photo by Naidu Rayapati. to become reddish or reddish purple among vines, we blotches and become strikingly appar- are referring to (NGS) technology to help in pathogen ent towards end of the season (Fig. 1). this disease using the umbrella term identification. “Grapevine Redleaf Disease” (GRD), to However, there was a wide variation help ensure that potential symptoms The results obtained from NGS revealed in symptoms across cultivars with red are not overlooked when scouting for presence of a single-stranded DNA vi- fruit. In some cases, leaves showed red this disease. rus, tentatively named as Grapevine or reddish-purple blotches on leaf mar- Redleaf-associated virus (GRLaV) and gins, and in other cases, the entire leaf What causes GRD? One of the first Grapevine fanleaf virus in grapevines showed red or reddish purple discolor- steps in determining whether symp- showing GRD symptoms. In contrast, ation. Even on an affected vine, individ- toms are caused by a pathogen rather Grapevine rupestris stem pitting-associ- ual leaves showed differing symptoms. than an abiotic stress is to see if those ated virus, Hop stunt viroid, Grapevine We did not observed any symptoms on symptoms can be transferred from af- yellow speckle viroid 1, Citrus exocortis V. vinifera cultivars with white fruit or in fected to healthy plants. One way to viroid (CEVd) and Citrus exocortis Yu- juice grape varieties (i.e., V. labruscana do this is to conduct grafting experi- catan viroid (CEYVd) were present in ‘Concord’). ments, where affected (i.e., symptom- both symptomatic and asymptomatic atic) tissue is grafted to healthy (i.e., grapevines. Molecular and phyloge- These symptoms appear to be similar, asymptomatic) tissue. When budwood netic analysis indicated that GRLaV is derived from symptomatic Merlot and a new geminivirus with a genome of vines was grafted onto 3,208 nucleotides (the individual com- Understanding Virus Names healthy Cabernet franc vines, we saw ponents of a DNA strand) and distinct When scientific names are used, a transmission of symptoms. This indi- characteristics from other members of they are typically presented in ital- cated the presence of graft-transmis- the virus family Geminiviridae. GRLaV is ics, such as Vitis vinifera (European sible pathogens associated with GRD almost identical to recently reported, wine grape). Italics are used to iden- symptoms. tentatively named, Grapevine Caber- tify: (i) that the name is in binomial nomenclature (Genus and species), net franc-associated virus (New York), and (ii) that, indirectly, these are the Since GRD symptoms were somewhat and Grapevine red blotch-associated names recognized across the scien- similar to GLRD symptoms, we then virus (California). tific community. proceeded to test samples with GRD This naming convention, however, symptoms for the presence of current- How is GRD spread? We have con- is not the same with viruses and vi- ly-known Grapevine leafroll-associated ducted preliminary, greenhouse-based roids. In the virus/viroid world, once viruses (GLRaVs) using molecular diag- feeding assays to determine how the the International Committee on Tax- nostic assays. These test results came GLRaV is spread. The results suggest onomy of Viruses accepts a name, it is italicized to demonstrate official back negative; we began to suspect that GLRaV may be transmitted by the recognition. For example, Grapevine that we were working with either (i) Virginia Creeper Leafhopper (Erythro- fanleaf virus is an officially recog- a potential ‘new’ strain of GLRaV, (ii) neura ziczac). As a note of caution, nized name (hence, in italics). When ‘new’ virus(es) in general, and/or (iii) these were greenhouse-based studies, a virus name is not italicized, it indi- and the precise role of a potential vec- cates that an official name has not new virus-like agent(s). Since identi- been given to the virus and multiple fying new disease agents can be dif- tor relationship has yet to be confirmed names may exist. Once an official ficult using traditional methods, we in a field setting. name is agreed upon, that official deployed Next Generation Sequencing name in italics will be used. continued on Page 7

6 Graft-Transmissible Grape Disease, con’t continued from Page 6

How can GRD be detected in plant tis- responding asymptomatic vines. An and viroids, we are currently develop- sue? We have developed a PCR-based analysis of fruit quality attributes in- ing molecular diagnostic assays for sen- method for the detection of GRLaV in dicated that berries from GRD-affect- sitive and specific detection of viruses both hardwood canes during dormant ed vines of both cultivars had lower and viroids in vineyards and for clean season and green tissue throughout amounts of total soluble solids (12% plant programs. We hope the develop- the growing season. Currently, the role less in Merlot, 14% less in Cabernet ment of new information will help pre- of the different viruses and viroids men- franc), lower berry skin anthocyanins vent the spread of new or newly-iden- tioned above in the production of GRD (4% less in Merlot, 9% less in Caber- tified pathogens, and aid in increasing symptoms is not clear. Since GRLaV net franc), and higher titratable acid- the awareness of newly-named diseas- was consistently found in vines show- ity (9% more in Merlot, 16% more in es, such as GRD, among growers and ing GRD symptoms, this virus has been Cabernet franc), compared to berries nurseries. largely implicated in the production of from asymptomatic vines. In contrast, the associated symptoms. Further stud- no significant difference was observed This work was supported, in part, by ies are in progress to understand the in juice pH. These results indicated a WSU-ARC, Washington State Grape and precise role of GRLaV in the develop- potential negative impact of GRD on Wine Research Program, USDA-North- ment of GRD symptoms. yield and key quality attributes. west Center for Small Fruits Research, and USDA-NIFA-SCRI (#2009-51181- What are the potential impacts of GRD? Conclusion. In summary, using NGS 06027), WSDA-Nursery Assessment To determine whether GRD was nega- technology, we have identified poten- Funds, Washington State Commission on tively impacting vine development, we tial viruses and viroids associated with Pesticide Registration, and USDA-APHIS compared yield and fruit quality from GRD symptoms. We are also determin- National Clean Plant Network. We thank symptomatic to adjacent asymptomat- ing the differences between GRD and Dr. James Harbertson for advice and Ms. ic vines of V. vinifera ‘Merlot’ and ‘Cab- GLRD in vineyards, in an effort to de- Maria Mireles for technical assistance in ernet franc’ in a commercial vineyard. ploy knowledge-based strategies for biochemical analysis of berry samples, In 2012, GRD-affected Merlot and the management of both diseases. and members of Eureka Genomics for Cabernet franc grapevines had 22% Finally, based on the success of using collaboration on the next-generation se- and 37% less yield compared with cor- NGS technology to identify new viruses quencing project. Call for Grower Collaborations / Demonstrations By Walsh Entomology Lab, WSU-IAREC

Grape Mealybug Monitoring - and placement, but scientists at WSU- ing at a way to identify different leaf- Concord Vineyards IAREC will do the trap counts and will hopper species using molecular tech- email weekly updates to vineyard man- niques. To gather data for this project, Curious about your vineyard’s grape agers. Currently, recommendations are we are requesting the participation mealybug population? Viticulture en- set at 1 pheromone trap per 30 acre from growers in and around the Yakima tomologists at WSU-IAREC are asking vineyard block. Traps are available on Valley, beginning early this summer. WA grape growers to participate in a a first-come, first-served basis, and grape mealybug monitoring program. should be in place by the beginning of As a part of this project, leafhoppers will This project is aimed at gaining an un- May. For more information and instruc- be collected from vineyards through- derstanding of what grape mealybug tions, please contact Brian Bahder at: out the growing season, then identified populations are doing, and if their be- [email protected] visually. These visual identifications will havior is different in different locations. be compared to PCR (genetic testing) This monitoring will be done using Leafhopper Monitoring - results. For more information or to ex- pheromone traps. All Vineyard Types press your interest in working with this project, please contact Doug Walsh at: Growers are responsible for trap costs We will also be starting a program look- [email protected] NOT RECEIVING WSU V&E EXTENSION EMAILS? Go to our website: http://extension.wsu.edu/irrigatedag and click the “Sign up now” link.

This service allows you to customize the information you receive. Choose from topic areas, including: Tree Fruit (apple, cherry, stone fruit, nursery, automation/mechanization), Grapes (juice, wine, table, win- ery), Other Small Fruit (blueberry, raspberry), Vegetables (potato, onion, sweet corn, peas, carrots, other veg- etables), Cereals/Row Crops (wheat/small grains, corn [grain and silage], dry edible beans, alternative crops), Forages (alfalfa, timothy, other grasses/legumes, mint), Livestock (cattle, swine, sheep, goats, pasture man- agement), Ag Systems (high residue farming, soil quality/health, organic ag, direct marketing, small farms), Water and Irrigation (center pivot irrigation, drip irrigation, surface irrigation, water availability/rights).

7 WSU Wine Sensory Purchases Electronic Tongue By Carolyn Ross, WSU-Pullman

Recently, the Ross Lab purchased a ysis process. Using novel piece of analytical equipment, wines that were pre- an Electronic Tongue (e-Tongue) by viously prepared, we Alpha-MOS (Fig. 1). The e-Tongue is a separated the different coated sensor array instrument with an treatments represent- integrated pattern recognition system. ed in this wines based It draws on the underlying principle of on their “taste finger- the neurophysiology of the sense of print” as determined taste; in other words, how our nervous by the e-Tongue. This system translates what we consume “taste fingerprint” is into a taste sensation. assessed based on a discrimination index The e-Tongue quantifies non-volatile (DI). The DI is an in- organic and inorganic compounds, dication of the abil- and similar to the human tongue, can ity of the e-Tongue to provide a “taste fingerprint” based on separate wine samples the non-volatile profile of the wine on their differences in (sweet, sour, salty, bitter, umami, me- sweetness, bitterness, tallic and savory). Using the e-Tongue, metallic, spiciness / we will be able to overlay sensory data savory, and sourness and see the influence of that sensory responses. A high DI data on wine differentiation. (>80) was observed among the samples. In a typical operation of the e-Tongue, the sensors interact with the solution The responses from via the electrical properties its vari- the e-Tongue for each ous chemical components. Our par- wine were then com- ticular e-Tongue uses a potentiometric pared to the sensory method of detection which measures a profiles generated us- voltage difference between a reference ing a trained sensory electrode and the various sensors (Fig. panel. This compari- 2). son showed a strong positive relationship Since the use of the e-Tongue is new, (r >0.93) between the there is not much known how to use e-Tongue and the sen- it to analyzed wine samples. Our lab sory panel for the at- has been working on developing these tributes of sweetness, Figure 1- Top: The e-Tongue Unit. Bottom: A close up of the methods to help standardize the anal- ethanol burn, astrin- membrane-coated sensor array. gency and bitterness. This indicates that for these attributes the e-Tongue does a good approximation of what a sensory panel would do.

With the rising popularity in wine comes the rising need for sensory re- search. Unfortunately, using human- based evaluation panels can be costly, time-consuming (training), and ridden with the inherent limitation of subjec- tivity. The e-Tongue may help alleviate these issues, as it showed great prom- ise in not only discriminating wine treatments, but also as a tool for pre- dicting the sensory attributes of wines. The Sensory Lab at WSU is one of the few research labs currently using this tool for wine analyses. In the future, we Figure 2- The e-Tongue works via Chemically Modified Field Effect Transitory (CHEMFET) sensors. It is composed of 2 highly conducting regions (source and drain), a sensitive layer plan on using the e-Tongue, in addition (coated membrane with determines the compound selectivity), and a polymer to protect to trained sensory evaluation panels, to the sensor in an aqueous solution. Detection of a compound is through the potentiometric describe differences between wines. method, where differences in voltage across two sensors is measured.

8 Thresholds and Rejection of TDN by Consumers By Carolyn Ross, WSU-Pullman

While at Lincoln University in Christ- paired preference testing to determine asked to indicate which sample was church, New Zealand for my research if the consumer would then reject that preferred (they did not know which sabbatical, my collaborator Roland wine. Both studies were conducted sample was spiked). Harrison and I explored an interesting at two locations, NZ (Lincoln) and at research question regarding 1,1,6-tri- USA (WSU-Pullman). Using these two The TDN detection threshold value in methyl-1,2-dihydronaphthalene different consumer populations al- Riesling for the NZ and USA consum- (TDN). This compound is important to lowed us to determine differences in ers was 37.9 and 43.2 μg TDN/L, re- the aroma profile of a matureVitis vi- rejection thresholds of TDN in Riesling spectively. No significant differences nifera ‘Riesling’ wine and contributes a wines across different regions/popula- in threshold values were observed be- ‘petrol’ or ‘kerosene’ note. tions. The consumers used in the study tween locations or replicate panelist. (n=36) were self-defined as “regular However, consistent regional differ- In wine, the TDN sensory thresholds, white wine consumers.” ences in TDN preference were found. or the lowest concentrations at which The consumer rejection threshold for the TDN can be detected by humans, To test for detection thresholds, 3 sam- USA was 64 μg TDN/L; the rejection have been defined. However, the TDN ples were given to each panelist, one threshold for NZ was 204.8 μg TDN/L. threshold that affects consumer ac- with a known quantity of TDN, two This suggests that consumers in both ceptability of a wine is not clear; these with no TDN. Panelists were asked to regions detected TDN at similar con- thresholds are typically higher than identify which sample was different centrations, but prefered / tolerated sensory thresholds. Unfortunately, from the others. This test started with different levels of TDN. Consumers in threshold determinations are notori- a low concentration of TDN, and then NZ tolerated a higher concentration of ously difficult, varying greatly with the increased that concentration with each TDN compared to those in the USA. methodology used to measure them. presented set of wines. To test for con- sumer rejection / preference thresholds, These results highlighted the influence To address this question of where each panelist received multiple pairs of of TDN on the acceptance of Riesling consumer rejection thresholds are for Riesling wine samples: one sample was wines, and may be useful for those TDN, we developed a protocol that: spiked with a known quantity of TDN, winemakers and marketers wishing to (i) Determined the threshold of TDN one did not contain any TDN. In each address differences in consumer prefer- in a given wine, and then, (ii) Used of these pairings, participants were ences across regions. Berry Water Economy, con’t continued from Page 5

water from the xylem. This means that REFERENCES drip irrigation late in the season does not “pump” water into the berries, 1. Keller M. The science of grapevines: thus would not “dilute” berry quality. anatomy and physiology. 2010. Burl- ington, Elsevier Academic Press. Overhead irrigation and rainfall could cause more water to be retained in 2. Matthews M.A., G. Cheng, and S.A. the berries and even more water to be Weinbaum 1987. Changes in water po- taken up directly through the skin or tential and dermal extensibility during stem surface, causing berries to crack. grape berry development. J. Am. Soci- In vineyards with overhead irrigation, ety of Horticulture Science 112: 314- late-season irrigation should be ap- 319. proached with caution due to the po- tential increase in berry cracking. 3. Becker T., and M. Knoche. 2011. Water movement through the surfaces Avoiding late-season irrigation, how- of the grape berry and its stem. Ameri- ever, when it is applied to the soil is can Journal of Enology and Viticulture unnecessary. Our research results sug- 62: 340-350. gest that late-season irrigation does not diluting berry quality when that ir- rigation is soil-applied. Moreover, soil- applied late-season irrigation should be considered to help replenish soil moisture before the dormant season, thereby reducing cold-damage risk to Figure 4- A root pressure chamber was used the vine root system. to stop xylem backflow by pressurizing the roots. Photo by Yun Zhang.

9 Wine Matrix: Tannin Extraction and Astringency By Federico Casassa, PhD Candidate, Richard Larsen, and James Harbertson, WSU-IAREC

In red wine production, winemakers crushing, maceration and wine aging. Tannins are complex molecules spend a considerable amount of time found in the skins, seeds and both in the vineyard tasting grapes, Effect on tannin extraction and evolu- stems of the grape berries and and in the lab interpreting berry basic tion during winemaking. The extraction are composed of individual units analysis (Brix, pH, acidity) and phenolic of tannins into wine and their fate dur- named flavan-3-ols. Tannins vary chemistry (anthocyanins, skin tannins in size according to the number ing post-maceration and aging is gov- of these units and are typically and seed tannins) as harvest approach- erned by the wine matrix composition. at higher concentrations in skins es. The goal is to assess the optimal Example components of the wine ma- (from 10 up to 80 units) than in fruit “ripeness” for a given wine style. trix composition include anthocyanins seeds (from 2 up to 15 units) and and other compounds such as manno- wines (from 2 up to 7 units). Tannins play a critical role in this op- proteins originating from yeasts, and timal “ripeness”, as they contribute to polysaccharides located in cell walls of increased polymeric pigment forma- the oral sensations of astringency, bit- mesocarp (i.e., pulp) and berry skin; tion, it did not increase tannin extrac- terness, and possibly other textural at- these components are known to react tion. tributes such as wine body and mouth- with wine tannins. feel. For many of the solutes presented In a separate study, where white wines in the berries (e.g., sugars, acids), a Presence of anthocyanins and formation were produced in contact with skins measurement of the amount in the of polymeric pigments. The presence of and seeds also had additions of an- berry provides a fair estimate of the anthocyanins during maceration in- thocyanins [4], polymeric pigments amount that will be extracted during creases the solubility and retention of and astringency levels were higher in maceration. Tannins, however, seem to tannins [2]. This occurs via the forma- the resulting wines, relative to those be an exception to that rule [1]. tion of polymeric pigments. Polymeric observed for the white wine produced pigments are extremely heterogeneous with the white pomace alone. Togeth- While Fig. 1 implies a simple extrac- winemaking artifacts composed pri- er, these findings suggest that the pres- tion curve of tannins during macera- marily of anthocyanins and tannins, ence of anthocyanins invariably leads tion, true tannin extraction and reten- but recent research suggests that to polymeric pigment formation. How- tion appears to be more complex than other wine constituents, such as poly- ever, the proportion of anthocyanins implied. Furthermore, the astringency saccharides, mannoproteins, organic and tannins during maceration will and bitterness sensations winemakers acids and carbohydrates, may also be determine the amount of wine tannins perceive when tasting isolated skins or involved in the chemical structure of that are retained. These hypotheses, seeds in the vineyard are perceptually such pigments [3]. In an experiment in however, remain to be tested. different, both in intensity and dura- which white wines were produced with tion, from those perceived during wine different portions of added tannins and There are scientific reasons, based on tasting. These simple observations anthocyanins, both tannin retention both chemical and sensory data, to suggest that major structural changes and formation of polymeric pigments believe that polymeric pigments con- involving tannins take place during increased in the presence of added an- fer desirable sensory traits to the final thocyanins [2]. wine. For example, relative to the intact This study also anthocyanins, polymeric pigments are found that the partially resistant to bisulfite bleaching stoichiometric and more resilient to pH changes [5]. addition of an- This means polymeric pigments con- thocyanins rel- fer to the wine a more stable and thus ative to tannins potentially long-lasting color. Beyond approached the influence of polymeric pigments in an ideal pro- color stability, direct sensory evidence portion; a of the role of these compounds in the concentration changes in mouthfeel and astringency excess of an- observed during wine aging is rela- thocyanins did tively recent. The observed ‘lessening’ not lead to a of astringency during wine aging was corresponding classically thought to be the result of increase in pig- the formation of polymeric pigments mented poly- mer formation. - Bisulfite (SO3H ) is a common pre- The levels of servative derived from added sul- tannins in both fur dioxide during winemaking wines were not that is able to bleach the through reaction with an- different, sug- thocyanins. Figure 1- Extraction of protein precipitable tannins measured as catechin gesting that equivalents (CE) during extended maceration in Vitis vinifera ‘Merlot’ while anthocy- wines. anin addition continued on Page 11

10 Wine Matrix, con’t continued from Page 10 involving anthocyanins and tannins of creasing tan- various sizes [6]. However, the struc- nins size [10], tural complexity and heterogeneity of and are de- these pigments prevented their isola- picted in Fig. tion and their chemical and sensory 2. characterization. With the advent of new analytical, semi-preparative and In wines, preparative high-performance liquid the failure chromatography (HPLC) approaches to recover coupled with nuclear magnetic reso- high molecu- nance (NMR), both the chemical and lar weight sensory characterization of these com- tannins is pounds has become possible. For ex- thought to ample, one study found that polymeric be the result pigments bearing an anthocyanin of tannin–cell moiety were less astringent than apple wall interac- tannins of the same size deprived of tions that oc- anthocyanins [7]. The comparatively cur during lower astringency of polymeric pig- winemaking ments relative to that of intact tannins [11]. Further- has been hypothesized to result from more, a se- an increase in the hydrophilic (water- ries of studies loving) character of the pigment due conducted by to the incorporation of the anthocya- the Austra- nins which have a sugar molecule at- lian Wine Re- tached to their structure [2]. This would search Insti- reportedly decrease the interaction of tute showed the tannin pigments with the proteins a significant founds in human saliva, thus reducing relationship astringency. As polymeric pigments between the were found to contain polysaccharides tannin molec- Figure 2- Schematic diagram indicating specific chemical interactions within their structure, the formation of ular mass and (hydrogen-bonding) between a tannin molecule (proanthocyanidin C1) soluble complexes that do not precipi- the propor- and a cell wall polysaccharide (homogalacturonan). Modified from Hanlin tate with salivary proteins (and hence tion of tannin et al. (2010). do not elicit astringency) is also a pos- adsorbed by sibility [8]. skin and pulp cell wall polysaccharides. under actual winemaking conditions The end result would be that higher have yet to be carried out. Therefore, the empirical observation molecular weight tannins are not ex- of decreased astringency in wine ag- tractable and/or removed from the Extended maceration, polymeric pig- ing may not be related to a change wine by interaction with cell wall com- ments, and missing tannins. Extended in the total amount of tannin present. ponents during maceration [12,13,14]. maceration increases the amount of Rather, the structural modification of If that hypothesis proves true, it would tannins retained into wine, and these wine tannins, primarily resulting from explain why, even though skin tannins tannins are mainly derived from the the incorporation of anthocyanins, are fairly large (between 20 to 30 and seeds [16,17]. Extended maceration and, secondarily from the addition of up to 80 flavan-3-ols units), the average can also promote the formation of other metabolites such as carbohy- molecular weight of wine tannins only polymeric pigments. Experiments con- drates, proteins, and polysaccharides, varies between 2 and 7 units [15,16]. ducted in the Research Winery at WSU- may drive the observed changes in per- Moreover, these interactions may also IAREC from 2010 to 2012 showed that ceived astringency during wine aging. explain the post-fermentation extrac- this enhanced polymeric pigment for- tion of wine tannins during extended mation during extended maceration Interaction between proanthocyanidins maceration. As ethanol can disrupt was generally due to the formation of and cell wall components during macera- these interactions, the post-fermenta- large polymeric pigments (assumed to tion. In apple cider production, there tion extraction of tannins observed in be composed of more than 3 flavan- is a lack of recovery of high molecu- Fig. 1 after day 20 could be the result 3-ol subunits in addition to one or lar weight tannins that were originally of a desorption mechanism mediated more anthocyanin molecules). Howev- present at the beginning of processing by ethanol, which leads to the disrup- er, enhanced formation of small poly- [9]. Chemical interactions between tion of these interactions between the meric pigments (assumed to be com- tannins and cell wall material are re- extracted tannins that were bound to posed by anthocyanin-tannin adducts sponsible for this ‘natural fining’ occur- cell wall material [1, 11]. Studies exam- of 3 units or less) was also observed. ring spontaneously during production. ining the effect of varying ethanol lev- These interactions increase with the in- els on tannin extraction and evolution continued on Page 12

11 Wine Matrix, con’t continued from Page 11 longed maceration equilibria, total phenols, free and molecular SO2 time may only act and chemical age. J. Sci. Food Agric. 28:279–287. by exacerbating this 6. Somers T.C.1971. The polymeric nature of matrix effect. wine pigments. Phytochem. 10:2175–2186.

Conclusions. Tan- 7. Vidal S., L. Francis, A.C. Noble, M. Kwiat- nin extraction into kowski, V. Cheynier, and E.J. Waters. 2004. Taste and mouth-feel properties of different types of wine is more com- tannin-like polyphenolic compounds and antho- plex than previously cyanins in wine. Anal. Chim. Acta 513:57−65. thought. It appears that tannin extrac- 8. Scollary, G.R., G. Pásti, M. Kállay, J. Blackman, and A.C. Clark. 2012. Astringency response of tion is governed by red wines: potential role of molecular assembly. a complex relation- Trends Food Sci. Tech. 27:25–36. ship between tannin content, anthocy- 9. Haslam, E. 1998. Practical Polyphenolics: From anin extraction (or Structure to Molecular Recognition and Physio- logical Action. Cambridge University Press, Cam- loss) and polymeric bridge, United Kingdom. pigment formation Figure 3- Mass balance showing the proportion of total tannin during maceration. 10. Le Bourvellec C., Guyot, S. and C.M. Renard. extracted into wine, recovered in the pomace and unaccounted for This points to a more 2004. Noncovalent interaction between procy- in Merlot wines. The results are the average values of six control anidins and apple cell wall material. Part I. Effect prominent role of the of some environmental parameters. Biochim. (10 days of skin contact) and six extended maceration (EM, 30 wine matrix, not only days of skin contact) tank replicates. Biophys. Acta 1672:192–202. as a determinant of Interestingly, upon analysis of tannins the tannin extrac- 11. Hanlin, R.L., M. Hrmova, J.F. Harbertson, and tion, but also in some sensory proper- M.O. Downey. 2010. Review: condensed tannin in fruit, wine and those recovered in and grape cell wall interactions and their impact the pomace after maceration, it was ties such as astringency. There is a need on tannin extractability into wine. Aust. J. Grape found that the proportion of tannins to understand the basic chemistry un- Wine Res. 16:173−188. that are unaccounted for (i.e., tannins derlying the interaction between tan- that were present in the fruit but can- nins, anthocyanins, polysaccharides, 12. Bindon K.A., P.A. Smith, and J.A. Kennedy. 2010 a. Interaction between grape derived pro- not be recovered in the wines or in the and mannoproteins during macera- anthocyanidins and cell wall material. 1. Effect skin and seed pomace samples after tion, as well as understanding the basic on proanthocyanidin composition and molecular maceration) was always consistently chemical effect of fermentation and/or mass. J. Agric. Food Chem. 58:2520–2528. higher upon application of extended oxidation products such as ethanol and acetaldehyde on wine sensations. An 13. Bindon K.A., P.A. Smith, H. Holt, and J.A. Ken- maceration (Fig. 3). In other words, nedy. 2010 b. Interaction between grape-derived the higher the amount of extracted understanding of these reactions will proanthocyanidins and cell wall material. 2. Im- tannins during extended maceration, allow scientists to model the evolution plications for vinification. J. Agric. Food Chem. the higher the proportion of missing of complex wine sensations, such as as- 58:10736–10746. tannins. We have also found that the tringency and bitterness, and ultimate- 14. Bindon K.A., A. Bacic, and J.A. Kennedy. proportion of unaccounted tannins ly help winemakers to produce wines 2012. Tissue-specific and developmental modi- varies between seasons, vineyards and according to specific stylistic protocols. fication of grape cell walls influences the adsorp- tion of proanthocyanidins. J. Agric. Food Chem. varieties. While some of these unac- 60:9249–9260. counted tannins may be incorporated REFERENCES into small polymeric pigments during 15. Hanlin R.L., M.A. Kelm, K.L. Wilkinson, and extended maceration, as we had ob- 1. Adams D.O., and R.C. Scholz. 2008. Tannins M.O. Downey. 2011. Detailed characterization of served, the amount of tannin incorpo- – the problem of extraction. In Proc. 13th Aus. proanthocyanidins in skin, seeds and wine of Shi- Wine Ind. Tech. Conf. Blair,pp. 160–164. Aus. raz and wine grapes (Vitis rated into these pigments can only be Soc. for Vitic. and Oenol., Adelaide, Australia. vinifera). J. Agric. Food Chem. 59:13265–13276. partially responsible for this compara- tively higher proportion of unaccount- 2. Singleton V.L., and E.K. Trousdale. 1992. An- 16. Casassa L.F., C.W. Beaver, M.S. Mireles, and ed tannins [16]. thocyanin-tannin interactions explaining differ- J.F. Harbertson. 2013. Effect of extended macera- ences in polymeric phenols between white and tion and ethanol concentration on the extraction red wines. Am. J. Enol. Vitic. 43:63–70. and evolution of phenolics, color components These data suggest that the longer the and sensory attributes of Merlot wines. Aust. J. Grape Wine Res. 19:25–39. maceration time, the more pronounced 3. Wollman N., and T. Hofmann. 2013. Compo- the matrix effect is on sequestering sitional and sensory characterization of red wine polymers. J. Agric. Food Chem. doi: 10.1021/ 17. Harbertson J.F., M. Mireles, E. Harwood, grape tannins. While an additional jf3052576 K.M. Weller, and C.F. Ross. 2009. Chemical and pool of tannins is indeed extracted sensory effects of saignée, water addition and during extended maceration, a por- extended maceration on high Brix must. Am. J. 4. Oberholster,A., I.L. Francis, P.G. Iland, and E.J. Enol. Vitic. 60:450–460. tion may be irreversibly bound to cell Waters. 2009. Mouthfeel of white wines made wall components from pulp cells, and with and without pomace contact and added anthocyanins. Aust. J. Grape Wine Res. 15:59–69. to polysaccharides or mannoproteins of grape and/or yeast origin, which are 5. Somers T.C., and M.E. Evans. 1977. Spectral removed after wine settling. The pro- evaluation of young red wines: Anthocyanin

12 Hello From New Technology Transfer Hire at WSU By Hemant Gohil, WSU-IAREC I joined Washington State University I have always been interested in the as a Technology Transfer Specialist application of technology to improve for the Viticulture and Enology Pro- crop production; I am excited to join gram in February 2013. Having com- WSU as a Technology Transfer Special- pleted my B.S. in Agriculture in India, ist. Based at WSU-IAREC in Prosser, I came to the USA to pursue a Mas- WA, I will closely work with Dr. Markus ter’s degree in Plant Science at Texas Keller to improve the understanding A&M University. After completing my of how sap bleeding is correlated with M.Sc., I went on to pursue a Ph.D. budbreak, vine vigor and fruitfulness in Agriculture Engineering at Univer- in different varieties of wine grapes. sity of Florida, Gainesville working For this, I am undertaking greenhouse on plant-water relationships in veg- experiments with potted vines adjust- etables. ed to moisture levels from permanent wilting point to field capacity in sandy Shortly after graduating in 2010, I or and how fertilization and irrigation and sandy loam soils. joined Viticulture and Enology Research could achieve optimal vigor and yield. Center at California State University I will also be working with Dr. Michelle in Fresno, working as a Post Doctoral On a second project, I looked at how Moyer on other research and Extension Research Associate. There, I was in- a plant growth regulator, abscisic acid activities. This will include conducting volved in several projects to address (ABA), effected wine grapes. In this survey work regarding the incidence the challenge of high temperatures project, we made wine from our ABA and severity of Grapevine Crown Gall, on color and flavor development in treatments, to see if there were differ- as well as working on a joint WSU- wine grapes. I used unique approaches ences in anthocyanins and phenolics. I USDA project relating to nematodes in such as crop forcing (double pruning) was also involved in interdisciplinary re- Washington vineyards. I intend to work to shift the timing of berry ripening in search projects with collaborators from closely with the industry and WSU to order to enhance fruit quality for wine USDA to study the anti-fungal activity develop active collaborations to sup- production in warmer climates. I stud- of non-toxic chitosan-based fungicides port the thriving wine grape industry ied how crop forcing affected vine vig- in table grapes. in the state of Washington. CALENDAR OF EVENTS

DATE DESCRIPTION 20-21 April 2013 WSU Vine to Wine Introductory Workshop, Prosser, WA 2 May 2013 Grape Fieldman’s Breakfast, Cafe Villa, Prosser, WA 6 June 2013 Grape Fieldman’s Breakfast, Cafe Villa, Prosser, WA 11 June 2013 Field Pest Scouting Workshop, Hood River, OR 24-27 June 2013 ASEV National Conference, Monterrey, CA 3 July 2013 Grape Fieldman’s Breakfast, Cafe Villa, Prosser, WA 8 August 2013 Grape Fieldman’s Breakfast, Cafe Villa, Prosser, WA 16 August 2013 WA State Viticulture Field Day, Prosser, WA Check the website for changes and updates to the Calendar of Events. http://wine.wsu.edu/category/events/ The next issue of VEEN will be in September and is accepting events between 1 September 2013 and 31 March 2014. Let Michelle ([email protected]) know of your events by 15 August 2013

France Winery Tour The WSU Viticulture & Enology Program is offering a Winery Tour from June 29 to July 13, 2013. This educational tour will visit the regions of Cham- pagne, Burgundy and Bordeaux.

See: http://wine.wsu.edu/education/certificate/international-winery-tours/ france-winery-tour/ for more information or contact Theresa Beaver at: [email protected] .

13