Honors College Thesis


Impact of pre-fermentation maceration techniques on yeast populations and color of Pinot noir wine Public Deposited

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  • The quality of red wine is primarily determined by the flavor, aroma, and color. A common wine making technique used to improve these characteristics is the pre-­‐fermentation maceration. In this study two pre-fermentation maceration techniques were used, one was a traditional cold soak and the second involved addition of dry ice to the grapes. Samples were taken daily and yeast viable cells were assessed by growth on WL media. This also enabled the major species of yeast to be identified. The two major yeast species seen throughout the pre-fermentation maceration were Pichia membranaefaciens and Kloeckera apiculata. Yeast population in both pre-fermentation macerations increased during the maceration period. However, after three days the population in the cold soak treatment was 1 log or greater than the yeast population in the dry ice treatment. This difference remained for the rest of the maceration. After wines were produced their color and phenolic contents were analyzed. Total color, polymeric pigments and monomeric anthocyanins in wines that underwent a pre-ferementation maceration were not significantly different than the control. However, there was a significant difference in the amount of tannins between the dry ice and cold soak treatment to the control.
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  • description.provenance : Submitted by Heather Boren (heather.boren@oregonstate.edu) on 2011-12-12T23:32:12ZNo. of bitstreams: 1Thesis Text ZOOK.pdf: 240450 bytes, checksum: 91e8c1d8984c107c65e4fa8f4635b75f (MD5)
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