difficult to ferment juices: strategies for fermentation management
DESCRIPTION
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). - PowerPoint PPT PresentationTRANSCRIPT
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DIFFICULT TO FERMENT JUICES: STRATEGIES FOR
FERMENTATION MANAGEMENT
Linda F. Bisson
Department of Viticulture and Enology, UCD
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Types of Difficult to Ferment Juices
• High Brix
• High Rot/High Bioload
• Vineyard Site Issues
• Varietal/Rootstock Issues
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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
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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)
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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
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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
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First StudyNitrogen Status and Fermentation Dynamics for Merlot on Two Rootstocks
Christine M. Stockert, Linda F. Bisson, Douglas O. Adams and David R. Smart
2013. AJEV
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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
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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?
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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
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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.
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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
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Results: Fermentation
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Results: Juice Nitrogen AnalysisNitrogen 1103
Control Spring N Fall N101-14 Mgt
Control 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
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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
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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
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Second Study
Difficult to Ferment Coastal Chardonnay Juices
Priyanka Dhar, Aline Cresswell, Vidhya Ramakrishnan, Gordon Walker
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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
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Fermentation Results: Yeast Strains Used in Study
Yeast StrainRestart Stuck
Temp. Range
Ferm. Speed
Competitive Factor
Alcohol Tolerance
Relative Nitrogen Needs
Lalvin ICV-D254
Lowest 12-28 Moderate Neutral 16 Medium
Lalvin Rhone 2226
Moderate 15-28 Fast Active 18 High
Uvaferm 43 Highest 13-35 Fast Neutral 18+ Low
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Fermentation Results
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Fermentation Results
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Fermentation Results
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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
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Amino Acid Composition of Juices 2010 Vintage
Juice FAN YAN/YNAN Proline/ Arginine
Dry Creek 324 1.2 6.6
Napa 246.6 1.5 7.2
J Lohr Difficult
157 0.46 32.6
J Lohr Easy 341.7 0.96 8.8
KAC 522.8 1.17 5.5
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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 2011Difficult
119.4 0.54 23.8
J Lohr 2012Difficult
216 0.76 12.4
J Lohr 2012Easy
306 0.98 9.14
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Fermentation Results 2012
0
2
4
6
8
10
0 50 100 150 200
Wei
ght
Loss
as
CO2
Time (hours)
J.Lohr Juice
Allegro E
Allegro D
Allegro D+
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Fermentation Results 2012
0123456789
0 50 100 150 200
Wei
ght
Loss
as
CO2
Time (hours)
J.Lohr juice
522 E
522 D
522 D+
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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
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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
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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?
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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