Hen egg white lysozyme is a hydrolytic enzyme effective at preventing
the growth of Gram positive bacteria by degrading the bacterial cell wall to a
point of cell lysis. Investigating lysozyme as a processing tool in wine to
control the growth of lactic acid bacteria and malolactic fermentation has
significant commercial interest. In this project, the interactions of lysozyme
with wine components and wine was evaluated along with the efficacy of
lysozyme in preventing malolactic fermentation (MLF) in Oregon Pinot Noir
and Chardonnay. The information from this work, together with results
from similar projects, will allow the development of guidelines for lysozyme
use in commercial wine.
Interactions of lysozyme with wine components were evaluated by
measurement of enzymatic activity in the presence of wine acids, ethanol,
and phenolics. Enzyme inhibition was observed, to various degrees, with all
wine components. Crude grape tannin altered the availability of free enzyme
by complexing to lysozyme and forming a precipitate. In a model wine
system, lysozyme activity was reduced by 50% when tannin was present.
Lysozyme addition to red wine resulted in a reduction in pigmented
compounds and detectable sensory differences.
Wine trials evaluated the efficacy of lysozyme in completely
preventing malolactic fermentation (MLF) and terminating MLF midway
through fermentation in Oregon Pinot Noir and Chardonnay. Vintages from
1993 and 1994 were treated without SO₂, with SO₂, with SO₂ plus a starter
culture of Leuconostoc oenos. Each lot was divided into 0 ppm lysozyme
(control), 250 ppm lysozyme, 500 ppm lysozyme, and 1000 ppm lysozyme.
Lactic acid bacteria were enumerated monthly, for ten months. Lysozyme
prevented malolactic fermentation in all wines at the treatment levels of 500
and 1000 ppm. In the 1993 Pinot Noir, 250 ppm lysozyme prevented MLF but
only delayed MLF in the 1994 vintage. Lysozyme effectively terminated MLF
at a concentration between 200 and 300 ppm in both Pinot Noir and
Chardonnay. / Graduation date: 1996
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27443 |
| Date | 13 July 1995 |
| Creators | Green, Jeffery L. |
| Contributors | Daeschel, Mark A. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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