Document Type

Thesis

Date of Degree Completion

Fall 2015

Degree Name

Master of Science (MS)

Department

Biology

Committee Chair

Holly Pinkart

Second Committee Member

Jennifer Dechaine

Third Committee Member

Jim Johnson

Abstract

The use of shortwave ultraviolet (UVc) radiation to control lactic acid bacteria (LAB) in wine production was studied. A simulated wine sterilizer was built using a commercially sourced ultraviolet (UV) sterilizer commonly used in aquariums and ponds. After growing cultures in test tubes, samples of five different species of LAB were introduced into white grape juice adjusted for brix and pH to match that of wine must commonly found in the Yakima Valley American Viticultural Area. The mixture was then agitated and allowed time to evenly distribute the bacteria throughout the juice. The juice was sent through the sterilizer in a single pass using an aquarium pump. LAB were quantified pre- and post-treatment using a dilution series on MRS agar. The UVc treatment resulted in a significant reduction of LAB by an average of 52.7% with a 95% confidence interval for three replicates of three trials. These data are compared to industry standards and applications of UVc sterilization in the wine industry with suggested areas for further study are discussed.

Language

English

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