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Postdoctoral Researcher in Analytical Chemistry | University of California Davis


University of California Davis


Location

Davis, CA | United States


Job description

Postdoctoral Researcher in Analytical Chemistry

Position Overview:
The posted UC salary scales set the minimum pay determined by rank and/or step at appointment. See Table 23: Postdoctoral Scholar-Employee, Postdoctoral Scholar-Fellow, Postdoctoral Scholar-Paid
Direct, Fiscal Year The salary range for this position is $64,480.00 - $74,569.00 . 'Off-scale salaries', i.e., a salary that is higher than the published system-wide salary at the designated rank and step, are offered when necessary to meet competitive conditions, qualifications, and experience.


We are seeking a highly motivated, organized, and dynamic scientist to fill a Postdoctoral Researcher position in Analytical Chemistry at the University of California, Davis (UCD) to work on a project titled: 'Determining the pool of smoke-derived compounds and their relative fate in grapes.' The incumbent will work within a large collaborative group of scientists and faculty from the Department of Viticulture and Enology (V&E) at UC Davis and from the Crops Pathology and Genetics Research Unit USDA-ARS (Davis, CA). The incumbent will also work closely with government agencies and local stakeholders, particularly grape growers and winemakers throughout California.

RESEARCH PROBLEM:
An increase in wildfire frequency and a lengthened fire season has detrimentally impacted vineyards, especially along the West coast in the United States. Smoke produced from wildfires negatively affects grape composition and wine sensory characteristics. The pyrolysis of a lignin source (e.g., wood, brush, grass) creates smoke that contains several volatile and semi-volatile organic compounds. Literature reveals that smoke-derived volatile phenols (VPs) are absorbed by the grape berries, converted to glycoconjugates, and extracted during winemaking, imparting a negative sensory attribute termed 'smoke taint'.

Research indicates that fuel type influences the composition of volatile phenols (VPs) in smoke, yet the impact of fuel type on the chemical composition of smoke-exposed grapes has not been evaluated extensively. Investigating the impact of smoke from various fuel types on grape chemical composition is likely to elucidate a larger pool of currently unidentified compounds associated with smoke taint. In addition, mass balance studies have not yet been able to efficiently track the fate of VPs after their absorption into the grape. Although it is known that VPs are glycosylated, an intermediate pathway is hypothesized. Further research is needed to reveal the fate of smoke-derived compounds in grapes and the variable impacts from fuel types. A broader understanding of the impact of smoke exposure on grape chemistry is essential to develop targeted and efficient methods of detection and amelioration.

Efforts of the Analytical Chemist Postdoctoral Researcher will be directed toward the determination of the pool of smoke-derived compounds and their relative fate in grapes.

OBJECTIVES:
1) Analyze the grape volatilome after exposure to smoke from various fuel sources
2) Determine if glycosylation reactions of VPs in the grape are a factor of fuel source
3) Elucidate the fate of smoke-derived compounds in the grape

APPROACH AND GOAL: To fully understand the impact of smoke exposure on grape chemical composition, it is necessary to determine if fuel type impacts the absorption of VPs into the grape and glycosylation reactions. This project will focus on fuel sources that are in American vineyard appellations in California. The plant species will be oak, pine, chaparral, and California oatgrass. Potted grapevines will be placed in a smoking chamber and will be exposed to smoke produced from 500g of fuel type over 5 hours. Grape samples will be collected at various timepoints post-exposure, up to one month. The grape volatilome will be analyzed through untargeted and targeted methods via GC-MS/MS. In conjunction, non-volatile secondary metabolites will be analyzed using uHPLC-QToF-MS to evaluate differences in glycoconjugates in grapes treated with smoke from different fuel types.

To determine the fate of smoke-derived compounds in the grape, grapevines will be exposed to smoke produced from the pyrolysis of C13 labeled California oatgrass. Potted grapevines will be exposed, and grape samples collected as previously mentioned. The metabolome and transcriptome of the grape samples will be analyzed to understand the impacts of smoke exposure on grape metabolic pathways.

MINIMUM QUALIFICATIONS


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