Transcript Decreasing Fermentation Time in White

Tom Mascara
Technical Manager
Enzyme Solutions Pty Ltd
Fermenting Yeast
Yeast Cell Wall
Protease Action and Fermenting Yeast
Yeast Cell Wall
Proteases in Yeast Fermentations
 Intact Yeast do not secrete their own proteases
 Adding additional proteases may help to break down
protein and provide more assimilable peptides and
amino acids for fermenting yeasts
Nutrient Requirements for Wine
 Successful fermentation from juice to wine require
adequate levels of available Nitrogen.
 The amount of nitrogen required is dependent on the
yeast strain and the fermentation conditions.
 Requirement is for minimum of 220 mg/L of nitrogen
(YAN) for complete fermentation, higher sugar juices
require more.
 Lack of nitrogen can lead to stuck fermentations
Wine Industry Practice
 Recommended to measure Yeast Assimilable Nitrogen
(YAN)
 Sum of NH4 and Free Amino Nitrogen measurements
 Di-ammonium Phosphate often used as NH4
 Commercial fermentation supplements (Yeast Foods)
are also available – mixtures of DAP, inactivated yeast,
vitamins, minerals.
Are all Nitrogen sources the same?
 Inorganic Sources
DAP
 Organic Sources
 From the grape
 Addition of inactivated yeast in fermentation aid
 Organic sources are recognized as the preferred source
– DAP is considered to be “Junk Food” for yeasts. It can
lower wine pH and produce unwanted flavours

Hypothesis:
 Can adding a protease enzyme also assist in wine
production by completing the fermentation and
decreasing the time?
Typical Fermenter Setup
Plot: Density vs. Time
14
12
Density
(o Baume)
10
Control
2 ppm
8
10 ppm
6
20 ppm
4
2
0
0
50
100
150
-2
Time ( Hrs)
200
250
300
350
3
Density (o Baume)
2.5
Control
2
2 ppm
1.5
10 ppm
1
20 ppm
0.5
0
144
164
184
204
224
244
-0.5
-1
Time ( Hrs)
264
284
304
324
344
Statistical Analysis
 All the results were adjusted to a zero baseline by adding
0.8 Be
 The area under each treatment curve was estimated by
the area of a trapezoid method, Single Factor ANOVA
and Multiple Comparison Tests to determine if there
was significant differences
 Results were significantly different at the P= 0.01 level
(99% confidence)
Summary of Results
 All fermentations performed similarly until they




reached ~0 Be (7-8 days).
Untreated control ferments slowed and appeared to
stop at -0.4 Be, indicating a slow or stuck fermentation
at day 14
At 0 Be, all the protease treatments continued to
ferment, finally settling at -0.8 Be (would be considered
finished in wine industry)
Reduced fermentation time with 10 & 20 mg/L finished
at 11 days, 2 mg/L finished at 12 days.
Importantly - No off-flavours with the proteases
Conclusions
 Addition of protease has ensured white wine
fermentations are complete with reduced fermentation
times
 The response was dose related, and 10 mg/L seems to be
sufficient as 20 mg/L only offered minimal advantage.
 Gives a winemaker additional confidence and potential
to increase Plant throughput by reducing their
fermentation times
 These results have led to the commercial formulation
and release of a yeast nutrient containing protease
activity.