Transcript Overview of problem fermentations

DIFFICULT TO FERMENT
JUICES: STRATEGIES FOR
FERMENTATION MANAGEMENT
Linda F. Bisson
Department of Viticulture and Enology, UCD
Types of Difficult to Ferment Juices
• High Brix
• High Rot/High Bioload
• Vineyard Site Issues
• Varietal/Rootstock Issues
High Brix (Long Hang Time)
• High sugar means high ethanol
• Increased demand for nutrients with increasing Brix,
may be as much as two-fold
• Long Hang Time means more juice seepage
• Increased potential for inhibitory lactic acid bacteria
populations on surface of fruit
• Higher pH of juice, greater activity of spoilage microbes
in winery
• Higher SO2 demand of juice
High Rot
• High microbial bioloads in juice
• Greater competition for nutrients
• Increased production of inhibitory compounds negatively impacting
fermentation progression
• Higher SO2 demands
• Nutrient level and timing of addition critical to assure
feeding the right population
• Temperature critical to fostering development of right
population (too warm favors bacteria, too cold favors
spoilage yeast)
Vineyard Site Issues
• Poor Soils
• Chronically Nutrient Deficient Juices
• Nutrient supplementation not always effective
• Complex nutrients needed
• Presence of fermentation/growth inhibitors from the vine
• High Disease/Pest Pressure
• Poor fruit nutrient content
• Presence of fermentation/growth inhibitors from the vine
Variety/Rootstock Issues
• Variation in fermentation progression as a function of
rootstock
• Often a soil composition component
• More severe with some varietals/clones than others
First Study
Nitrogen Status and Fermentation
Dynamics for Merlot on Two Rootstocks
Christine M. Stockert, Linda F. Bisson,
Douglas O. Adams and David R. Smart
2013. AJEV
Outline of Study
• Compare impact of N fertilization at two seasonal
time points: fall and spring on two rootstocks,
101-14Mgt and 1103P
• Merlot clone 1 used as scion
• Assessed leaf %N and fruit amino nitrogen
composition
• Monitored fermentation dynamics
Questions to be addressed:
• Is Leaf %N correlated with amino acid composition
of grapes?
• Can Leaf %N predict fermentation performance?
• Do rootstocks differ in uptake and utilization of N
with respect to berry composition?
Details of Merlot Trial
• Experiment was carried out in the UCD vineyard in Oakville,
California
• The vines were in their tenth year and trained as bilateral
cordons with vertical shoot positioning (VSP)
• The trellis height was 1.6 m and the canopy was hedged to
2.2 m.
• The rows were oriented SE to NW and spaced 2.4 x 2.2 m
between and within rows respectively
• Vines on 1103P were established and managed with 28
nodes while those on 101-14 Mgt were established and
managed with 24 nodes
• A randomized complete block design with six blocks was
used. Each block consisted of subplots of six vines per
rootstock x treatment combination
Details of Experimental Design
• The Spring fertilized treatment was 16.8 kg N/ha applied on 18 May
2005 and the Fall fertilized treatment was 16.8 kg N/ha applied on 7
October 2004 using potassium nitrate (36.94% K, 13.75% N) applied
through the drip line
• The vines were deficit irrigated bi-weekly with 40% replacement of
crop ETc, which totaled 60 mm over the course of the summer.
• Irrigation water and fertigation solution were delivered via one 3.8 L/hr
drip emitter per vine, located 50 cm from each trunk.
Results
• Leaf N levels similar for both rootstocks
• 101-14 Mgt had fewer leaves, less total canopy nitrogen
• Leaf number but not nitrogen level per leaf associated
with nutrient deficiency caused by rootstock
Results: Fermentation
Results: Juice Nitrogen Analysis
Nitrogen
Control
1103
Spring N Fall N
Control
101-14 Mgt
Spring N Fall N
Total Free AA,
mg/L
509
565
557
228
278
249
Arginine, mg/L
85
115
111
14
22
14
Proline, mg/L
1101
1227
1191
802
967
824
YAN/YNAN
0.46
0.46
0.46
0.28
0.28
0.28
Pro/Arg
19.9
16.2
15.8
87.1
66.6
89.6
Questions to be addressed:
• Is Leaf %N correlated with amino acid composition
of grapes? NO
• Can Leaf %N predict fermentation performance?
NO
• Do rootstocks differ in uptake and utilization of N
with respect to berry composition? YES
Conclusions
• Grape/Juice N varies by rootstock
• Nitrogen additions in vineyard might not impact juice YAN
as much as thought
• Yeast YAN not predictable from Vineyard N assessments,
although there is often a trend
• Sluggish juices are characterized by low YAN/YNAN and
high Proline/Arginine ratios
Second Study
Difficult to Ferment Coastal Chardonnay
Juices
Priyanka Dhar, Aline Cresswell, Vidhya
Ramakrishnan, Gordon Walker
The Issues:
• Vineyard blocks characterized by low vine N
• Vine N less responsive to N application than other
blocks in vineyard
• Chronic issues with fermentation progression
• Yeast fermentation does not respond to yeast
nutrient addition
Fermentation Results: Yeast Strains
Used in Study
Yeast Strain
Restart
Stuck
Temp.
Range
Ferm.
Speed
Competitive
Factor
Alcohol
Tolerance
Relative
Nitrogen
Needs
Lalvin ICVD254
Lowest
12-28
Moderate
Neutral
16
Medium
Moderate
15-28
Fast
Active
18
High
Highest
13-35
Fast
Neutral
18+
Low
Lalvin Rhone
2226
Uvaferm 43
Fermentation Results
25
L2226R1
Dry Creek Valley juice
L2226 R2
L2226R3
20
L2226R4
Degree Brix
L2226 R5
L2226 R6
D254 R1
15
D254 R2
D254 R3
D254 R4
10
D254 R5
D254 R6
UV43 R1
5
UV43 R2
UV43 R3
UV43 R4
0
UV43 R5
0
24
48
72
96
120
144
Time (hours)
168
192
216
UV43 R6
Fermentation Results
25
Napa Valley Juice
Degree Brix
20
15
10
5
0
0
24
48
72
96 120 144 168 192 216 240 264 288 312
Time (hours)
LR1
LR2
LR3
LR4
LR5
LR6
DR1
DR2
DR3
DR4
DR5
DR6
UR1
UR2
UR3
UR4
UR5
UR6
Fermentation Results
25
J. Lohr Difficult to Ferment Juice
20
Degree Brix
15
10
5
0
Time (hours)
LR1
LR2
LR3
LR4
LR5
LR6
DR1
DR2
DR3
DR4
DR5
DR6
UR1
UR2
UR3
UR4
UR5
UR6
Fermentation Results
• Easy to ferment juices generally finished in 8
days at fermentation temperatures of 60° F
• UV43 in Napa juice took 12 days
• In difficult to ferment juice, strains took 14-18
days to complete fermentation
Amino Acid Composition of Juices 2010
Vintage
Juice
Dry Creek
FAN
YAN/YNAN
Proline/
Arginine
324
1.2
6.6
246.6
1.5
7.2
157
0.46
32.6
J Lohr Easy
341.7
0.96
8.8
KAC
522.8
1.17
5.5
Napa
J Lohr
Difficult
Amino Acid Composition of Juices 2011,
2012 Vintages
Juice
FAN
YAN/YNAN
Proline/
Arginine
J Lohr 2010
Difficult
157
0.46
32.6
J Lohr 2011
Difficult
119.4
0.54
23.8
J Lohr 2012
Difficult
216
0.76
12.4
J Lohr 2012
Easy
306
0.98
9.14
Fermentation Results 2012
J.Lohr Juice
Weight Loss as CO2
10
8
6
Allegro E
4
Allegro D
2
Allegro D+
0
0
50
100
Time (hours)
150
200
Fermentation Results 2012
Weight Loss as CO2
J.Lohr juice
9
8
7
6
5
4
3
2
1
0
522 E
522 D
522 D+
0
50
100
Time (hours)
150
200
Conclusions from Chardonnay Study
• Difficult to ferment Chardonnay juices also show low
YAN/YNAN ratios and high Proline/Arginine ratios
• Nutrient supplementation does not affect rate of
fermentation of difficult to ferment juices
• Also a rootstock effect? Difficult to ferment Chardonnay is
Clone 5 on 5C
Overall Conclusions
• Difficult to ferment juices are challenging to
yeasts regardless of innate nutritional
requirements
• Difficult to ferment juices do not respond to typical
yeast nutrient additions in winery
• Although low in N, it is not clear low N is the
reason difficult to ferment juices are so difficult to
ferment
• Correction of problem in vineyard may be
challenging as it requires high N applications
Cause of Difficulty in Fermentation?
• Not chloride or other inhibitory ion
• Does not respond to ammonium addition
• Metabolome analysis: yeast have high concentrations of
stress-associated metabolites, especially mannitol
• Not associated with wild lactic activity
• Oxidative stressors?
• Inhibitory phenolics/plant metabolites?
Acknowledgements
Funding
• American Vineyard Foundation
• USDA Viticulture Consortium
• California Grant Program for Research in
Viticulture and Enology
• Maynard A. Amerine Chair Endowment
• VEN Department Scholarships