A vital component of the Oregon Wine Research Institute’s “vine to wine” research approach is the ability to conduct a large number of controlled, research scale fermentations. This has allowed studies such as “Managing Nitrogen in the Vineyard or the Winery” to be performed or the 2020 project where eighty-four micro-fermentations of smoke impacted grapes from all across Oregon were conducted to provide information on the impact of smoke exposure in different regions and on different grape varieties. While the current research winery has served us admirably in the past, it is undersized and underequipped to meet our current and future needs. This hinders the ability for OSU to conduct research to address current and emerging industry priorities, such as mitigating the impact of smoke exposure from wildfires and recruiting and training the next generation of winemakers and viticulturists. Therefore, the primary need of the OSU enology program is a well-equipped winery with increased capacity for experimental winemaking.
An exciting opportunity to expand and update the winery has recently presented itself. The building the research winery is currently housed in, Withycombe Hall, will soon undergo a $55 million, fully funded renovation. This renovation will increase available space for the winery from approximately 800 sq feet to over 2,000 sq feet. With the infrastructure needs taken care of, all we need to do is fill that space with equipment essential for enology research and teaching. This will include the addition of a large number of small capacity research fermenters and appropriately scaled processing equipment, as well as a winery laboratory fully equipped to conduct essential grape and wine analysis. Investment in the new winemaking facility will provide the OSU enology program with a state-of-the-art winery with outstanding capabilities comparable to our peers at other Universities. In addition, larger-scale equipment for teaching purposes will strengthen training of current students along with providing improved work force training through extension courses.
The Erath Family Foundation has generously kicked off our $531,000 fundraising campaign with a gift of $100,000 and a promise to fund another $100,000 if the remaining $331,000 is raised by December 2022. Sam Tannahill and Cheryl Francis also committed to a $100,000 gift for this opportunity leaving $231,000 left on our goal. There are opportunities at many different levels to contribute as we fundraise towards this goal. If you are interested in finding out more about the winery renovation, please contact James Osborne at email@example.com or call 541-737-6494. He would be happy to talk with you about the plans for the winery and how this facility will have a profound impact on our ability to conduct enology and viticulture research and train the next generation of winemakers and viticulturists. You can also contact Amy Crumley (firstname.lastname@example.org), the Senior Director of Development for the College of Agricultural Sciences, for more details on how to partner with us on this project.
Dr. Michael C. Qian, Professor (food chemistry), Oregon State University
Grapevine Red Blotch Virus (GRBV) is a single-stranded circular DNA virus that can cause Grapevine Red Blotch Disease (GRBD). The virus was first identified in Cabernet Sauvignon grapes in 2008 in California, and now the disease is known to be widespread in many wine grape-growing regions in North America. The leaves of infected grapevines turn red, and the fruit does not ripen, typically having reduced Brix and color (anthocyanin). Specifically, GRBV inhibits grape ripening pathways by altering transcription factors and hormone networks, disrupting normal grape berry development.
To better understand the impacts of GRBD on grape and wine quality – and potentially remedy the issue – we examined wine aroma composition of wines produced from GRBV positive vines that had undergone two different leaf removal treatments. This work was done in conjunction with Dr. Patty Skinkis (Professor and Viticulture Extension Specialist) and Dr. James Osborne (Professor and Enology Extension Specialist), both of OSU. The leaf removal trial was implemented in 2018-2020 growing seasons with 100% cluster zone leaf removal applied pre-bloom and compared with east-side cluster zone leaf removal by machine at fruit-set (industry-standard method). The result showed that earlier and more complete leaf removal increased monomeric anthocyanin and phenolic compounds in wines. The early 100% leaf removal led to higher levels of bound form grape-derived aroma compounds in wines compared to the standard practice (E side only leaf removal at fruit set by machine). While leaf removal increased bound grape-derived aroma compounds, it did not impact fermentation-derived volatiles as there were no significant differences in these compounds between treatments. This study suggests early leaf removal may lessen the effect of red blotch disease on grape anthocyanin content and potentially improve aroma composition.
This research was funded by industry donations granted to the Oregon Wine Research Institute.
Dr. James Osborne, Associate Professor and Enology Extension Specialist, Dept. Food Science & Technology, OSU
The pH meter is arguable the most important piece of laboratory equipment you have in your winery. It is used for many routine analyses such as pH, titratable acidity, and as part of the analysis of volatile acidity. Accurately knowing your grape and wine pH is also critical in the management of microbial stability. Spoilage microorganisms such as Pediococcus and Brettanomyces are less acid-tolerant than beneficial microorganisms such as Saccharomyces cerevisiae and Oenococcus oeni. Lower pH, lower microbial spoilage risk; higher pH, higher microbial spoilage risk. Furthermore, there is a key relationship between pH and free SO2. At lower pH, a greater proportion of free SO2 is present as molecular SO2, the most effective antimicrobial form of SO2. Because of this, free SO2 concentrations should always be evaluated in conjunction with pH when considering target SO2 levels. A pH meter will provide you with a pH value, but how do you know that the value is accurate? The consequences of using a pH meter that is not functioning properly can be significant. For example, an inaccurate pH meter may lead to over or underestimation of SO2 additions needed to achieve a target molecular SO2 concentration and/or what acid adjustments are required pre- or post-fermentation.
So how can you ensure you are getting accurate and reliable results from your pH meter? Firstly, make sure you are using an appropriate pH electrode probe for grapes and wine. Not all pH electrode probes are suited to the unique physical and chemical composition of grape juice and wine. Many manufacturers have pH probes specific for grape and wine analysis, ensuring you are using the right tools for the job. Secondly, instigate a regularly scheduled calibration schedule in the winery lab. It should be standard practice to perform a calibration the first time the pH meter is used for the day. A logbook kept by the pH meter can be used to keep track of when calibration has been conducted and the result. If you have multiple people using the pH meter, they can quickly see when the last calibration occurred and know whether calibration is needed. Keeping track of the calibration results can help indicate if the probe may need to be cleaned or other reoccurring issues. Typically, you will have a small vial of each buffer for the calibration. These vials of buffer should be regularly changed out for fresh buffer solutions bi-weekly or monthly, depending on how often you use them. Make sure the buffers you are using match the built-in calibration set points for your pH meter. Most commonly, you will be using pH 4.0 and 7.01 set points, but some pH meters use pH 3.0 and 7.01. A buffer of 10.01 can also be used as a third calibration point, although in wine, you will be mainly measuring between pH 3.0 and pH 4.0, so this is where the greatest accuracy is required. The slope should be within ± 5% of the ideal (100%), while ± 10% or greater is considered out of range. Make sure you store the probe in an electrode storage solution (typically a KCL solution). A dried-out probe slows the exchange of ions between the probe and the solution you are measuring and results in false readings. Do not store in water or pH 7.01 buffer as this will result in leaching of the electrolyte solution from the pH probe. Some pH probes allow re-filling of the electrolyte solution, so keep an eye on this level if this is the case and re-fill when necessary (see manufacturers recommendations).
If you are starting to see pH drift and/or calibrations are challenging to conduct or have low accuracy, your pH probe may need cleaning. The build-up of grape and wine deposits on the outside of the pH probe bulb will cause fouling of the membrane and interfere with the interaction of ions in your juice/wine and the electrolyte solution. During heavy use, it may be necessary to clean your pH probe weekly or bi-weekly. This involves soaking the probe in a probe cleaning solution (often provided by probe manufacturers) for 30-60 minutes, followed by rinsing with DI water. This will improve the accuracy of your data as well as extend the life of your pH probe. Keep track of when cleanings occur in your pH meter logbook. By following a regular calibration and cleaning schedule for your pH meter/probe, you can ensure reliable and accurate pH data and improve the lifetime of the probe.
Dr. James Osborne, Associate Professor and Enology Extension Specialist, OSU
The malolactic fermentation (MLF) is a vital step in the production of cool climate red wines
as well as some white wines. But despite its importance, MLF often gets taken
for granted and just considered a step to reduce wine acidity. However, MLF is
much more than just a biological de-acidification process and can have a number
of other impacts on wine quality. Our lab has been conducting a number of projects
over recent years investigating various aspects of MLF. One project is
investigating interactions between Oenococcus
oeni and the spoilage yeast Brettanomyces
bruxellensis. An interesting result from this study was discovering that
some O. oeni strains were capable of
increasing the concentration of the volatile phenol precursors p-coumaric acid and ferulic acid. These
pre-cursor compounds are found in grapes and wine mainly bound to a tartaric
acid and in this form are not utilized by Brettanomyces.
However, some O. oeni strains can
remove the tartaric acid through the action of an enzyme, cinnamic esterase,
and release free p-coumaric and
ferulic acid that Brettanomyces can
then metabolize to 4-ethylphenol and 4-ethyl guaiacol. This finding has led to
the labelling of many commercial O. oeni
strains as either cinnamic esterase (+) or (-) with the recommendation being to
avoid use of cinnamic esterase (+) strains in situations where the wine may be
at risk for Brettanomyces spoilage.
additional area of research has been determining the effect of MLF on red wine
color. We know that MLF changes wine pH which can cause a shift in red color,
but were there other impacts on color due to MLF? Our lab demonstrated that
independent of pH change, MLF results in a loss of color and lower formation of
polymeric pigments. Results from a number of studies showed that this color
loss was likely due to the metabolism of acetaldehyde by O. oeni. Acetaldehyde plays a key role in the development of
polymeric pigments and so metabolism of acetaldehyde during MLF reduced
formation of these color compounds. Delaying MLF was shown to help mitigate
this color loss but delaying MLF for long periods is risky from a microbial
spoilage point of view, as SO2 cannot be added to the wine until MLF
is complete. Additional strategies to mitigate color loss due to MLF are
currently being explored. One such strategy is the use of ML bacteria that do
not metabolize acetaldehyde. To date, all O.
oeni strains screened can metabolize acetaldehyde but other lactic acid
bacterial species such as Lactobacillus
look more promising. There has been renewed interest in using certain Lactobacillus species and strains to
conduct MLF. In particular, homofermentative species of Lactobacillus have been studied as potential ML starter cultures.
These bacteria do not produce acetic acid from glucose metabolism and so could
be used for conducting concurrent alcoholic and malolactic fermentations
without the risk of increased acetic acid. Currently, there are commercially
produced L. platarum cultures
available outside of the USA for use in winemaking. However, at this time these
cultures are not available for winemaking use in the USA.
use of concurrent alcoholic and malolactic fermentation is one final area our
lab has been studying. While there are obvious time advantages to conducting
alcoholic and malolactic fermentation at the same time, there are still some
concerns over the impact on wine quality, particularly for red wines. We
recently completed a study investigating how the timing of MLF impacts
Chardonnay aroma and mouthfeel and will be continuing work in this area focused
on concurrent fermentations of red wines. As we continue to study malolactic
bacteria, we are gaining a better appreciation for the impact they can have on
wine quality and potential new strategies for their use. For additional
information on any of the studies we have conducted on MLF please contact me