College of Agricultural, Human, and Natural Resource Sciences
Voice of the Vine – Dec. 13, 2012 – Spoilers
Student Traces the Biochemical Pathways of Wine Spoilers
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 http://bit.ly/KHX8h4.
For more information on the work in Edwards’ lab, see http://bit.ly/Sj5bU2.
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.
The release of a new winter wheat variety named “Jasper” honors the legacy of the wheat breeding program at WSU started by William Jasper Spillman in 1894. The first variety developed by the university was released in 1905. Jasper marks the 100th.
The Rock Doc is a nationally syndicated newspaper column written by Dr. Kirsten Peters, covering many scientific and research related topics in a upbeat and entertaining fashion. Dr. Peter’s humor and anecdotes help to bring these stories to a public audience by showing how they affect everyday life. The most recent articles are linked below.
Students have a variety of options to pursue masters and doctoral degrees. Many of these have very specific background requirements, so we suggest exploring the individual programs for academic guidelines.
Being a CAHNRS Coug is about having a life-changing experience and having fun along the way. With an endless array of subjects to study, students can explore a variety of topics until they focus on that area that truly excites them. We include ample opportunities to learn outside the classroom, because we not only believe it’s a better way to learn, it makes for a more meaningful and enjoyable college experience.
The Center for Transformational Learning and Leadership makes it possible for students to secure that job-landing internship, experience another culture in the southern hemisphere, unlock their leadership potential through seminars and workshops, and find a mentor to coach them through their academic experience.
CAHNRS knows how to throw a party, and there is not greater time to celebrate than when our students return to campus. Free food (including Ferdinand’s Ice Cream), swag from each of our student clubs, activities, and a drawing for $1,000 scholarships—its all part of our annual Fall Festival. And we just don’t limit the event to our CAHNRS majors, we welcome everyone across campus to learn more about what our college offers.
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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.
Pullman, Wash. – You generally don’t find livestock among the hills of the Palouse region of eastern Washington where grain is grown. But wheat farmers Eric and Sheryl Zakarison are changing that – and making a profit.
On 100 of their 1,300 family owned acres, they are experimenting with a rather unconventional scheme for the region – growing wheat, peas, perennial grasses like alfalfa and sheep in a tightly integrated system. MORE
The watermelon crop has declined dramatically in Washington because of disease. But Washington State University researchers are developing a solution that involves grafting watermelon plants onto squash and other vine plant rootstocks.
“We’ve lost about a third of our state’s watermelon production over the last 10 years because of Verticillium wilt,” said Carol Miles, a professor of vegetable horticulture at the WSU Northwestern Washington Research and Extension Center in Mount Vernon. “Growers have switched to other crops that are less susceptible.” MORE
Gender and personality matter in how people cope with physical and mental illness, according to a paper by a Washington State University scientist and colleagues at the University of the Thai Chamber of Commerce.
Men are less affected by a single-symptom illness than women, but are more affected when more than one symptom is present. The number of symptoms doesn’t change how women are affected, according to Robert Rosenman, WSU professor in the Department of Economic Sciences. MORE
PULLMAN, Wash. – Researchers know that adding natural buffers to the farm landscape can stop soil from vanishing. Now a scientist at Washington State University has found that more buffers are better, both for pleasing the eye and slowing erosion.
Linda Klein, a recent doctoral graduate in WSU’s School of the Environment, worked with six other researchers at the university, plus one at the U.S. Department of Agriculture’s Moscow (Idaho) Forestry Sciences Laboratory, to explore the role that buffers – strips or clumps of shrubs, trees and natural vegetation – play in the landscape and in people’s visual preferences.
Klein surveyed Whitman County residents to see if conservation features made for more scenic fields and valleys. She found that Palouse residents prefer more nature with their wheat fields.MORE
By Sylvia Kantor, College of Agricultural, Human & Natural Resource Sciences
In the world’s driest rainfed wheat region, Washington State University researchers have identified summer fallow management practices that can make all the difference for farmers, water and soil conservation, and air quality.
Wheat growers in the Horse Heaven Hills of south-central Washington farm with an average of 6-8 inches of rain a year. Wind erosion has caused blowing dust that exceeded federal air quality standards 20 times in the past 10 years. MORE
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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.
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.
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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