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40 WINES&VINES December 2016 THE BEST OF 2O16 EDITORIAL Best-Read Grapegrowing Article of 2016 "TRACKING SOIL MOISTURE TO BETTER USE WATER" by Andrew Adams A guide to choosing and using soil- moisture sensors in the vineyard, published in the March 2016 issue of Wines & Vines, was the most- read grapegrowing story of the year. The item grew out of senior editor Andrew Adams' research for our monthly Product Focus feature. The guide broke moisture sensors into two main categories: those that measure soil water content and those that measure water tension. According to viticulturist Fritz Westover, a contributor to Wines & Vines, finding a location to install the sensor is as important as which type you buy. Doug Beck, a soil sci- entist with Monterey Pacific, said a well-positioned sensor offers a clear view of when a vineyard needs to be irrigated, and when it does not. Best-Read Winemaking Article of 2016 "KEY POINTS OF THE BOTTLING PROCESS" by Hend Letaief Shortly before leaving Califor- nia State University, Fresno, where she served as assistant professor of wine chemistry, Hend Letaief published a study of 17 wineries with the goal of iden- tifying points in the bottling pro- cess when oxygen is able to enter wine, altering its color and flavor. The result, published in the May 2016 issue of Wines & Vines, was our best-read winemaking story of the year. Letaief analyzed details including the use of inert gas before and/or after filling, hose length, bottling speed and clo- sure type to create a list of best practices for managing total package oxygen at bottling. Some of the advice already is common practice (flushing bot- tles with inert gas, applying vac- uum at corking), but other items on the list are small details that many don't consider (buying lon- ger hoses to reduce the number of connections, for example). 36 WINES&VINES May 2016 May 2016 WINES&VINES 37 WINEMAKING PRACTICAL WINERY & VINEYARD PRACTICAL WINERY & VINEYARD WINEMAKING In general, a winemaker should target a maximum of 1.0 mg/L of TPO at bottling, but this can be difficult to achieve. Levels above 2.5 mg/L can be problematic with a consider- able effect on wine shelf life and sensory profile. Nomacorc's research team revealed that the aroma of Chardonnay wines is altered four months after bottling when wines are exposed to more than 2.5 mg/L of TPO. 12 The decrease of the fruity aromas in Chardonnay wines was associated with an increase in oxi- dation, caramel and honey characters. The ultimate goal of managing TPO during bottling is to reduce bottle-to-bottle variation and provide the same tasting experience for the wine consumer. While most oxygen-manage- ment studies have focused on wine aroma and sulfur dioxide consumption, it is obvious that we are lacking information about how the TPO is affected by bottling practices. Several points need to be addressed as to when the most oxy- gen is dissolved into a wine during bottling as well as how this could be prevented. To examine the bottling processes that have an impact on TPO, California State University, Fresno, embarked on a collaborative study with Nomacorc. Bottling audits Oxygen has the potential to dissolve into wine at every stage of the bottling process. Different cellar practices can have different impacts on TPO. In order to analyze the possible sources of oxygen intake, bottling audits were conducted at 17 California wineries ranging in production capacity from less than 5,000 gallons per year to approximately 120,000 gallons per year. Eight white wines and nine red wines were ana- lyzed for oxygen uptake during bottling using different closure types: eight lots closed with natural cork, five lots closed with Nomacorc synthetic closures, four lots received screwcaps and one lot received agglomerated cork. Total package variations were studied based on the following critical cellar practices with impact on oxygen ingress: • Type of wine • Type of closure and bottle used • Bottling tank volume and diameter • Length and diameter of hose between bottling tank and filler bowl • Number of filling spouts and closure heads • Bottled volume and line speed • Technology of filling • Use of wine to prime the circuit and volume used • Use of inert gas before the process to maintain inert headspace in the bottling tank, inline, to inert bottles before and after filling, at corking, for purging of caps (yes/no and type), and at the end of a bottling run • Use of vacuum (and level of vacuum in negative millibar) at corking B ottling is a complex and delicate step of the winemaking process that requires a lot of professional expertise. Maintaining wine quality during bottling, storage and shipping is one of the highest priorities, and the objective is clear: protect the wine from oxida- tion as long as possible. Implementation of good bottling prac- tices begins with preparation adapted to the type of wine and the marketing channel. It continues with careful monitoring of the bottling line and, most important, the oxy- gen intake (pickup). To obtain a full assessment of oxygen pickup, instrument manufacturers and wine experts have undertaken new efforts to mea- sure total package oxygen (TPO), 1 which is the sum of dissolved oxygen (DO) and head- space oxygen (HSO) in the bottle. Measuring HSO can be achieved using a needle that goes through the closure and is directly connected to an analyzer. 2 An alterna- tive method consists of estimating TPO by measuring DO only after shaking the bottle to obtain equilibrium of oxygen pressure between the headspace and wine. 3 With the development of non-destructive analytical instruments (PreSens, Noma- Sense), a complete assessment of the bottling process is now possible. Luminescence-based technologies allow for non-invasive measure- ment of dissolved oxygen and headspace oxy- gen through the glass bottle wall. 4 Oxygen can dissolve into the wine at every stage of the bottling process, and it can have an effect on wine composition, shelf life and consumer acceptance. During bottling, wine undergoes multiple operations: pumping, fil- tration, filling and corking or capping. These operations are particularly conducive to the dissolution of oxygen in wines. At each transfer, and with each treatment, oxy- gen may penetrate and dissolve in the wine, with an average pickup (introduction) of 1.6 mg/L. 5 As wine progresses through bottling, a so-called "U-curve" of dissolved oxygen occurs. High amounts of oxygen are introduced at the begin- ning and end of the bottling process, and lower and steady levels are common in the middle of a bottling lot. 6 According to Zoran Ljepović, Constel- lation Brands quality assurance director, the bot- tling process should start with a DO of less than 1 mg/L, and if any increase occurs throughout the run, it should be maintained below 0.3 mg/L. 7 At filling, oxygen concentration in bottle headspace can range from 1.5 to 2.5 mg/L. 1 The oxygen concentration depends on three factors: wine volume, headspace volume and oxygen concentration in the headspace. Thus, at the end of the packaging process, it is pos- sible to find wines with dissolved oxygen levels ranging from 2 to 4 mg/L and a final oxygen content approaching 8 mg/L. 8 Measurement of total package oxygen Dissolved in excessive amounts, oxygen can cause irreversible changes in the color of the wine and its flavor profile after packaging. The influence of oxygen on red wine aroma com- pounds and sensory properties has been more difficult to confirm compared to effects on wine color. In a two-year Cabernet Sauvignon wine closure trial, M.J. Kwiatkowski showed that, with larger headspace, significant losses of SO 2 are observed soon after bottling, and wines developed a higher oxidized aroma score. 9 White wines contain lower levels of poly- phenols than red wines (0.2 to 0.5 g/L), mainly hydroxycinnamic acids, but these remain very important for oxidation and hence contribute to browning and loss of varietal aroma. 10 Measurements can be performed in real time using specific equipment for assessing oxygen at critical steps (transfer, filtration, bottling and storage). These measurements can be performed directly on the transfer lines and in the bottles (dissolved oxygen in the wine and gaseous oxy- gen in the headspace). Ken Fugelsang, professor emeritus of enology at California State University, Fresno, recommended TPO levels below 1.25 mg/L in bottled red wines and below 0.6 mg/L for white and rosé wines at bottling. 11 Key Points of the Bottling Process Study at 17 wineries identifies impacts on total package oxygen By Hend Letaief TPO VARIATION MID-BOTTLING PROCESS 4 3.5 3 2.5 2 1.5 1 0.5 0 Oxygen concentration (mg/L) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Winery Number n HSO n DO TPO: 0.6 - 3.3 ppm DO: 0.2 - 1.6 ppm HSO: 0.3 - 2.3 ppm TPO is mostly driven by HSO Total package oxygen (TPO), head space oxygen (HSO) and dissolved oxygen (DO) values identified among the 18 audits ranged between 0.6 and 3.3 mg/L. CELLAR PRACTICES AND TPO Audit 11 (TPO<1mg/L) Audit 2 (TPO>3mg/L) General features Wine type Red White Bottled volume (gallons) 19,325 6,500 Bottling speed (bottles/minute) 176 135 Hose length (meters) 24.5 103 Closure type Natural cork Screwcap Number of filling spouts 54 36 Number of corking/capping heads 9 6 Methods for DO management during transfer Use of inert gas to maintain inert headspace in bottling tank N 2 No Use of wine to prime the circuit 25 gallons 50 gallons Use of inert gas before bottling run N 2 N 2 Use of inert gas at end of the bottling run N 2 No Methods for DO management during filling Use of inert gas to purge the bottle N 2 N 2 Technology of filling Vacuum Vacuum Methods for HSO management after filling Use of inert gas after filling N 2 N 2 Use vacuum at corking -102 millibar - Inert gas sparging under screwcap - N 2 The lowest total package oxygen (TPO) level among the 18 audits was recorded during Audit 11, which had a TPO level of 0.6 mg/L. Audit 2 had the highest TPO level of 3.3 mg/L. Information about the equipment used and management procedures are detailed in the above table. Dissolved in excessive amounts, oxygen can cause irreversible changes in the color of the wine and its flavor profile after packaging. WINERY & VINEYARD EQUIPMENT 34 WINES&VINES March 2015 O ne can safely assume that in com- ing years water will continue to get more expensive, more scarce or (most likely) both. Yet the technology to measure soil-mois- ture content has continued to improve, and today growers can choose from a variety of sensors. The data from such sensors is vital to ensure an irrigation program is using water as effectively and efficiently as possible and can be incorporated into a precision-agricul- ture system to help growers make even better vineyard-management decisions. Several companies sell individual sensors as well as other equipment for data logging or to download and interpret data. Other firms like Hortau, Fruition Sciences and Ranch Systems use soil moisture sensors as part of broad networks that provide ex- tremely detailed irrigation reports, analysis and recommendations. When it comes to just moisture sensors, there are two main categories: those that measure the water content of soil and those that measure water tension or how easy it is for roots to take up moisture. Moisture con- tent, volumetric or capacitance sensors use time domain reflectometry (TDR) and trans- missometry (TDT) while water tension is determined with tensiometers and matric potential sensors. Neutron probes are another option that are quite accurate and draw data from a large area, but they are expensive and require extra permits and training because they use radioactive material. Most companies that use neutron probes either have the resources to train someone to use them full time or work with a consulting firm that uses them. First, find the right spot Viticulturist Fritz Westover is the founder and owner of Houston, Texas-based Westover Viticulture and the former technical program manager for the Vineyard Team in Atas- cadero, Calif. During his time with Vineyard Team, Westover wrote a guide about using soil moisture sensors for irrigation management. The guide is still available at the group's website, vineyardteam.org. Part of the re- port appeared in the June 2015 issue of Wines & Vines (see "Where to Install Soil Moisture Sensors"). Before choosing and investing in what type of sensor to purchase, Westover said growers should first determine the best spot to locate sensors. He said the first step is to understand one's soil profile through soil maps, excavation pits or soil core samples pulled with a hand auger. Westover said his soil auger by AMS is one of his most valuable vineyard tools. "The real important thing is putting it in the right spot and making sure it's installed correctly," he said of sensors. "That's probably more important than the type of sensor you pick." After determining soil type and stratifica- tion, a grower should then analyze vine vigor through his or her own observations or normal- ized difference vegetation index (NDVI) map- ping. The goal is to place the sensor in a location that has the soil profile and charac- teristics that represents an "average" of the entire block. Doug Beck, a soil scientist and agronomist with the large grapegrowing enterprise Mon- terey Pacific, has a Ph. D. in soil science from the University of California, Davis, and has worked with moisture sensors in vineyards along California's Central Coast since 1998. "One of the most important attributes for me is that the data is recorded on a regular basis and then stored for viewing as a graphic," he said. "This way the full point (field capacity) and fill point (when moisture becomes limit- ing) for the soil can be easily understood." He said most sensors offer logging capa- bility and, if installed correctly, almost all can provide good data. For Monterey Pacific, Beck said he chose to install Gro Point sen- sors from Environmental Sensors Inc. (ESI) because they use time domain reflectivity and measure moisture content in a fairly large area. "It is accurate if installed cor- rectly, and most of the sensors I installed in the late '90s are still working and showing the same fill and full points for the sites where they are installed." Monterey Pacific's sensors are located about 15 inches deep near the main root uptake area and at the bottom of the root zone, which is around 4 feet. Beck said such a setup offers a clear view of when a vineyard needs to be irrigated and when it does not. Tracking Soil Moisture to Better Use Water Find the right sensor for your vineyard By Andrew Adams Having accurate and timely data can make irrigation more efficient. ADCON Best-Read Wine East Story of 2016 "NEW VINES ARE GAME CHANGERS IN ALABAMA" by Randal Wilson The notoriously hot, humid summers of Alabama make it a natural fit for brewing iced tea and lemonade. Making wine, however, comes with extra challenges. Glassy-winged sharpshooter and leafhoppers are common in the area, and the insects are known vectors for Pierce's dis- ease, which cuts off the water sup- ply in grapevines, leading to scorched leaves and eventual death. This unhospitable growing envi- ronment served a purpose for Dr. Andrew Walker of the University of California, Davis, who worked with two Alabama vineyards to test his selections of PD-resistant vines bred for their potential to make high-quality wine. A story about the project was the most-read Wine East feature from the past year. In his story, Randal Wilson, winemaker for the Southern Oak Wines pro- duced at White Oak Vineyards in Alabama, recounts his experience planting and training PD-resistant vines at White Oak and describes the wines each are expected to yield once fully established. According to Wilson, "The availability of PD-resistant wine grapes that produce high-quality vinifera wines is a game changes for all wineries and wine growers in the Pierce's disease-prone regions of the eastern United States. We can finally grow and produce wines that are competitive." June 2016 WINES&VINES 61 WINE EAST GRAPEGROWING KEY POINTS Most grapes grown in Alabama are muscadines or hybrids that are resistant to Pierce's disease (PD) but do not have the flavor profile of wines made from vinifera grapes. New PD-resistant vinifera vines developed at the University of California, Davis, give Alabama growers new choices. Two Alabama vineyards signed up to be test sites for the PD-resistant vines from UC Davis. Both wineries planted PD-resistant vines in 2014 and again in 2016. Grapevines resistant to PD also were planted at Auburn University's Chilton Research and Extension Center (CREC) near Clanton, Ala., in 2010. Six years later, all the vines are free of PD and producing quality fruit. A fter several years of effort, the goal of planting Pierce's disease (PD)-resistant vinifera wine grapes at White Oak Vineyards in northeast Alabama is finally a reality. When we first opened our doors in 2004, the idea was to produce a variety of wines grown on our own estate. We started out planting muscadine grapes along with several French hybrids including Cham- bourcin, Chardonel, Seyval Blanc, Villard Blanc and Norton, along with several trials of T.V. Munson and Florida varieties. It quickly be- came apparent that the Munson and Florida varieties were PD resistant but exhibited strong herbaceous, foxy characteristics that we found unpleasant and, for the most part, missed the mark when it came to consumer preference. All the other varieties slowly died from Pierce's disease except for Norton and Villard Blanc, and the Villard Blanc did in fact succumb after 10 years to something resembling PD. That left us with Norton, which produced a good wine, though it still has a slight herbaceous, foxy character. It was painfully clear that winegrowers in the northern tier of the southeastern United States have limited choices, as the wines from the most PD-resistant wine grapes were almost undrinkable. There was an upside to all of the different bunch grapes that I grew at White Oak Vineyards: I learned how to manage and control the big four fungal diseases that are present and persistent in the eastern United States: powdery mildew, downy mildew, phomophsis and botrytis bunch rot, along with others. Early on, I discovered a spray guide from Michigan State University that was well written, easy to follow and, most im- portantly, its advice worked. While I still refer to it today, I have developed my own spray guide based on the prevailing climatic factors, time of the growing season and different sensitivities of the grapevines. This is underpinned by what I New Vines Are Game Changers in Alabama Growing Pierce's disease-resistant vinifera wine grapes in northeast Alabama By Randal Wilson These Pierce's disease- resistant vines are healthy after six years at the Chilton Research and Extension Center near Clanton, Ala. Best-Read Top Story of 2016 "STRONG DEMAND MEETS TIGHT GRAPE SUPPLY" by Andrew Adams Since rolling out our Top Stories feature in December 2013, the edi- torial staff of Wines & Vines have hand-selected 85 of the most important news and trend stories in the wine industry and devoted reporters to uncovering what is behind them. Our most-read Top Story of 2016 examined how the diminished harvest of 2015 affected the bulk wine market. According to Turrentine Bro- kerage partner Marc Cuneo, Sonoma County Chardonnay doubled in price as buyers real- ized the state's most common wine varietal is not limitless in quantity. Prices for Cabernet Sauvignon have grown steadily since 2011, but juice from Napa Valley reached an unprecedented $45 per gallon as a result of the smaller harvest. The broker said that the 2016 crop was mostly spoken for a full two months before the start of harvest in California, as buyers eager to replenish their reserves made sure to lock in fruit sources before picking got under way.