To provide a possible alternative for the antimicrobial action of sulfur dioxide
in winemaking, and address the issue of stuck fermentations, I studied the efficacy of
chicken lysozyme (EC 3.2.1.17) as an antimicrobial in grape juice. Two different
forms of lysozyme were used: native lysozyme (NL), that is known to be an effective
inhibitor of lactic acid bacteria in wine, and partially unfolded lysozyme (PUL), that
has been reported to have antimicrobial activity against both Gram-positive and Gram-negative
bacteria. Lactobacillus kunkeei and Acetobacter pasteurianus, two bacteria
associated with the induction of stuck fermentations were used in the experiments.
Chardonnay and Pinot Noir juices were inoculated with L. kunkeei and two
days later with yeast strain EC1118 and then incubated for 10 days. The addition of
250ppm of either NL or PUL reduced populations of L. kunkeei to less than 10
CFU/mL in 24 hours while in inoculated grape juice that did not contain any
lysozyme, the bacteria grew to 10⁹ CFU/mL within two days. Grape juices supporting
the growth of L. kunkeei developed up to 14 times more volatile acidity (VA) than the
control or either of the lysozyme treatments. No differences were observed in the
antimicrobial action of NL and PUL or in their effects on the composition of the wine. / Graduation date: 2002
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/25938 |
| Date | 22 June 2001 |
| Creators | Hetz, Uri |
| Contributors | Daeschel, Mark A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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