College of Agricultural, Human, and Natural Resource Sciences

Voice of the Vine – Dec. 13, 2012 – Spoilers

Student Traces the Biochemical Pathways of Wine Spoilers

Lauren Schopp in the lab, preparing a sample of red wine before using high-performance liquid chromatography to quantify levels of spoilage precursor compounds.
Lauren Schopp in the lab, preparing a sample of red wine before using high-performance liquid chromatography to quantify levels of spoilage precursor compounds.

What are spoilage yeast and bacteria doing in wine, aside from spoiling wine? Lauren Schopp, an M.S. student in the Washington State University/University of Idaho School of Food Sciences, decided to investigate spoilage yeast and bacteria by tracing their biochemical pathways, or the ways they interact with chemicals already present in wine. She specifically looked at Brettanomyces bruxellensis, perhaps the Godzilla of spoilage yeast, and Pediococcus parvulus, a bacterium common to red wines but whose impact on quality isn’t well described. Although Brett and Pediococcus can grow independently, these two troublemakers flourish in one another’s company.

The food chain for Brett and Pedio starts with the grape, particularly the skin, which has naturally occurring compounds called hydroxycinnamic acids, often in the form of tartaric acid esters. Partly as a result of the winemaking process, a portion of these esters are transformed into acid forms that are precursors to spoilage compounds. Both Brett and Pediococcus metabolize those acid precursors, producing intermediate vinyl compounds. Brett then metabolizes the vinyl compounds to producing compounds in wine that taste or smell “off.”

Schopp, mentored by enology professor Charles Edwards, worked with samples of Merlot, Syrah, Cabernet Sauvignon and Pinot Noir donated by a Washington winery. Measuring levels of the precursors using high-performance liquid chromatography, Schopp found relatively high concentrations of caffeic acid in the Washington Merlot and Cabernet Sauvignon samples, higher than concentrations often cited in scientific literature. This should not immediately set off an alarm, however, because caffeic acid metabolizes into 4-ethylcatchol, which, while a spoilage compound, has a relatively high sensory threshold, meaning that wine would need high levels before it could affect flavor and aroma.

Concentrations of p-coumaric acid and ferulic acid, also precursors to spoilage compounds, were found to be within normal levels in the wine samples.

After introducing two strains of Pediococcus and four strains of Brettanomyces to various wine samples, Schopp determined that Pediococcus was quite partial to caffeic acid. It metabolized a smaller portion of p-coumaric acid, but didn’t bother with ferulic acid at all.

Brett behaved a bit differently, with its consumption of the precursors being strain-dependent. One of the strains of Brett failed to grow in the wine as its populations slowly declined over time. While utilization of caffeic acid and ferulic acid varied significantly depending on the strain, the remaining three strains showed a strong fondness for p-coumaric acid, using nearly all the available precursor. The decrease in p-coumaric acid and ferulic acid corresponded with an increase in their spoilage metabolites, 4-ethylphenol and 4-ethylguaiacol. However, not all results were this clear-cut. Significant variations in precursor metabolism often emerged depending on the type of wine and whether Brett, Pediococcus, or both were introduced to the sample. While Brett and Pedio flourished in each other’s company, this didn’t always result in increased metabolism of the precursors.

The good news for winemakers is that neither Brett nor Pedio could break down the tartaric acid esters of hydroxycinnamic acids, compounds which could have served as a large pool of precursors to foul-smelling compounds. Schopp’s research gives some insight into the behavior and interaction of Brettanomyces and Pediococcus in wine, although more work is necessary to get a better handle on controlling the spoilers. Her research was funded by the Washington Wine Advisory Board.

Beyond her lab work with wine and its spoilers, Schopp’s accomplishments include a first-place team award at the 2012 “Developing Solutions for Developing Countries” national competition. Schopp served on the student team that created “Mango Maandazi,” a fried bread product incorporating mangos to address harvest and nutrition issues in Kenya. For more information on the Mango Maandazi project, see

For more information on the work in Edwards’ lab, see

-Bob Hoffmann

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CAHNRS is more than agriculture. With 24 majors, 19 minors, and 27 graduate level programs, we are one of the largest, most diverse colleges at WSU. CAHNRS Cougs are making a difference in the wellbeing of individuals, families, and communities, improving ecological and economic systems, and advancing agricultural sciences.



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CAHNRS leads in discovery through its high-quality research programs. In 2014, CAHNRS received research funding exceeding $81.5M. This accounts for nearly 40% of all research funding received by WSU.  


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Welcome back, CAHNRS Cougs, to another exciting year at WSU. CAHNRS has experienced quite a bit of change and growth recently, but we remain committed to serving the needs of our students, faculty, and staff.

As you may have heard, our dean, Ron Mittelhammer, has been appointed interim co-provost for the university. For the duration of his appointment, I have been named acting dean for the college.

I appreciate the support I have received from around the college, and am working with the associate deans, faculty, and staff to continue CAHNRS on its positive trajectory.

Part of that trajectory is a return of the Forestry major in WSU’s School of the Environment. As a college, we’re excited to help students get started in careers as foresters, environmental consultants, reforestation specialists, and wildfire management specialists.

Those last two are obviously of timely importance, as we are experiencing the worst wildfires in our state’s history blazing across our state and region. We hope that future wildfires will cause less devastation to people and the environment because of the work our Forestry majors will do.

We would also like to welcome the WSU Children’s Center to CAHNRS. The Center, which provides care for the children of WSU students, staff, and faculty, is now part of the CAHNRS Department of Human Development. The idea for this came from President Floyd, and we’re happy to carry out his vision.

Speaking of vision—I hope your vision for your WSU education includes at least one internship experience. Our internship program adds practical, extra value to your WSU education through our Center for Transformational Learning and Leadership. The CTLL is your gateway to internships, leadership training, mentoring, and more. That ‘more’ includes connection, inspiration, transformation, and leadership.

I hope you’ll celebrate this new school year with us at our annual Fall Festival on September 10, 4–6 p.m. in Spillman Plaza, between Johnson and Hulbert Halls. We’ll have free food, fun, and games. Watch for more details on our CAHNRS Facebook page.

We in CAHNRS are here to help you grow, learn, and succeed in this changing world. We’re glad to have you with us as we continue to push forward as leaders in research, education, and world-class academics.

Welcome back, and Go Cougs!

Kimberlee Kidwell
Acting Dean, College of Agricultural, Human, and Natural Resource Sciences


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The goal of the Washington State University CAHNRS Office of Research is to promote research beneficial to the citizens of Washington. The Office of Research recognizes its unique land-grant research mission to the people of Washington and their increasing global connections. The CAHNRS Office of Research provides leadership in discovering and applying knowledge through high-quality research that contributes to a safe and abundant food, fiber, and energy supply while enhancing the sustainability of agricultural and natural resource systems.

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‘A quiet crisis’: The rise of acidic soil in Washington

Gary Wegner first noticed the problem in 1991, when a field on his family’s farm west of Spokane produced one-fourth the usual amount of wheat. Lab tests revealed a surprising result: the soil had become acidic.

Study: Small railroads important but costly to upgrade

More than half of Washington’s short-line rail miles aren’t up to modern standards, according to a recent study by the Washington State Department of Transportation and the Washington State University Freight Policy Transportation Institute.
A grizzly bear with her cubs at the WSU bear center.

Single hair shows researchers what a bear has been eating

By looking at a single hair, U.S. and Canadian researchers can get a good idea of a grizzly bear’s diet over several months.

Fighting wildfires economically complex, says WSU researcher

Fighting wildfires is expensive. Firefighters must be paid and equipment must be purchased and transported to fires. Operations and maintenance cost money. According to a WSU researcher, the incentives to lower those costs are out of balance, and the researchers are working to understand the sources of the incentive problems.

Research shines light on organic fruit, food safety

The growing organic produce industry may soon have a new way to ensure the safety of fresh fruits. Scientists at Washington State University have shown that ultraviolet C (UVC) light is effective against foodborne pathogens on the surface of certain fruits.

Organic agriculture more profitable to farmers

A comprehensive study finds organic agriculture is more profitable for farmers than conventional agriculture. The results show that there’s room for organic agriculture to expand and, with its environmental benefits, to contribute a larger share in feeding the world sustainably.

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MudflatImpact: Burrowing Shrimp and Invasive Eelgrass

Shellfish production in Washington is a $60 million a year industry. Several major pests plague this industry, resulting in major crop loss. One of the most important pests is subterranean burrowing shrimp. These shrimp bioturbate (stir up) the sediment, causing the oysters to sink and die. For the past 60 years the industry has been using the insecticide Sevin to control this pest, but due to lawsuits its use was phased out in 2012. Without alternative control for shrimp, tens of millions of dollars in annual crop revenue will be lost and the industry will quickly lose its economic viability in southwestern Washington.

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The Environmental Protection Agency has identified agriculture as the leading contributor of pollutants to the nation’s rivers, streams, lakes, and reservoirs. These reports often do not separate animal agriculture from other agricultural enterprises, but they do note that pathogens, nutrients, and oxygen-depleting substances associated with manure are three of the top five pollutants. Some emerging issues related to manure management include: endocrine disruptors (hormones), pharmaceuticals (antimicrobials), and antibiotic resistance in bacteria. Adopting farm practices that minimize the environmental impact is important for food safety.

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Biosolids are the solids produced during municipal wastewater treatment. Composts are made from a variety of organic materials, including both urban and agriculture sources such as yard trimmings, biosolids, storm debris, food waste or manure, and food processing residues. While these materials have traditionally been viewed as waste, they can play a valuable role as soil amendments in urban and agricultural settings. They provide nutrients and organic matter and they sequester carbon, thereby conserving resources, restoring soils, and combating climate change.

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The College of Agricultural, Human, and Natural Resource Sciences (CAHNRS) at Washington State University is an expansive and diverse college that includes 16 academic units, 4 research and extension centers distributed across the state, 13 subject matter centers, and 39 county and one tribal extension offices.

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